Clinical and pathologic characteristics of dilated cardiomyopathy in hemodialysis patients

Understanding uremic cardiomyopathy: from pathogenesis to diagnosis and the horizon of therapeutic innovations

Uremic cardiomyopathy (UC) is a significant cardiovascular complication in individuals with end-stage renal disease. This review aims to explore the multifaceted landscape of UC, including the key pathophysiological mechanisms, diagnostic challenges, and current therapeutic approaches. The prevalence of cardiac hypertrophy, as a hallmark of UC, is highlighted and some new insights to its intricate pathogenesis, involving uremic toxins, oxidative stress, and inflammatory responses is elucidated. Diagnostic complexities, including the absence of specific biomarkers, are discussed, and the need for advanced imaging modalities and emerging diagnostic strategies are emphasized. Current therapeutic interventions, although lacking specificity, are addressed, paving its way to the potential future directions in targeted therapies. The review concludes new insights into the critical importance of ongoing research and technological advancements which will enhance early detection, precision treatment, and ultimately improve outcomes for individuals with UC.

Role of kidney transplantation in long-term cardiac reverse remodeling and interconnecting mechanisms in type 4 cardiorenal syndrome

Background

Type 4 cardiorenal syndrome (CRS) involves cardiovascular alterations caused by chronic kidney disease (CKD). Fibroblast growth factor-23 (FGF23), carboxy-terminal propeptide of procollagen type I (PIP), and parathyroid hormone (PTH) have been proposed as biomarkers of pathological cardiac remodeling in CKD. In contrast, it has been suggested that MicroRNA 221 has a cardioprotective role. Available evidence shows that, 12 months after kidney transplantation (KT), type 4 CRS reverts in only half of the patients.

Objective

To assess long-term cardiac reverse remodeling after KT and its association with FGF23, PIP, and PTH levels.

Methods

Patients with end-stage renal disease were assessed before and 28 months after KT using FGF23, PIP, and PTH serum concentrations and transthoracic echocardiography.

Results

Fifty-three patients were followed for 28 months after KT. All the patients showed cardiac abnormalities upon inclusion. A follow-up assessment showed a reduction in left ventricle (LV) mass (121 ± 48 vs. 65 ± 14 gr/m2) and left atrial volume (46 vs. 30 ml/m2). The LV ejection fraction (53 vs. 63%), LV global longitudinal strain (-15.9 vs.-19.4%), and LV diastolic function improved. miR-221 expression increased after KT (8.73 RIQ= 3.7-25 vs. 40.16 RIQ= 24-223, p=0.001) and was correlated with the Ee´ratio (r= -0.32, p= 0.02). Multivariate analysis showed that post-KT LV mass was determined by pre-KT LV mass, serum Cr level, post-KT PIP, and hypertension (R2 = 0.65, F=12.1, p=0.001).

Conclusions

Contrary to other evidence, this study demonstrated that type 4 CRS is reversible over the long term. This is a paramount finding because KT normalizes cardiac structure and function independently of the severity of basal cardiac abnormalities.

Myocardial involvement in end-stage renal disease patients with anemia as assessed by cardiovascular magnetic resonance native T1 mapping: An observational study

Cardiovascular disease has become to the main cause of death in the patients with end-stage renal disease (ESRD), and anemia is associated with increased cardiovascular morbidity and mortality in these patients. This study aimed to explore the impact of anemia on myocardial fibrosis using T1 mapping technique in patients with ESRD. A total of 128 subjects including 98 ESRD patients (65 with anemia, 33 without anemia) and 30 normal controls were enrolled. All subjects were underwent cardiovascular magnetic resonance to obtain cardiac cine and T1 mapping images. As potential markers of fibrosis, native T1 values and global longitudinal strain derived by feature-tracking technique were compared. Differences between 3 groups were analyzed using one-way analysis of variance. Associations between variables were assessed by Pearson and Spearman correlation coefficient appropriately. An independent association was identified by the multiple stepwise linear regression analysis. Intraclass correlation was applied to assess observer variability. In all ESRD patients, native T1 values were significantly longer than those of normal controls (global T1, 1357 ± 42 ms vs 1275 ± 48 ms, P < .001). Global T1 value in ESRD patients with anemia was significantly higher (1375 ± 36 ms) compared to that in ESRD patients without anemia (1322 ± 25 ms) and normal controls (1275 ± 48 ms), respectively (all P < .001). Global T1 correlated with hemoglobin negatively (R= -0.499, P < .001). Multiple stepwise linear regression analysis presented the anemia is independently associated with global T1 (R = 0.607, P < .001). Global longitudinal strain was remarkably reduced in ESRD patients with anemia in comparison to those without anemia (P < .001). Diffuse myocardial fibrosis could be detected by native T1 mapping in ESRD patients with long-term anemia. Anemia is an important factor in myocardial fibrosis in ESRD patients, and the evaluation of myocardial involvement is worth considering for clinical management.

What to do with foundation therapies for heart failure for patients with end-stage kidney disease on haemodialysis

There is a significant burden of cardiovascular disease morbidity and mortality in the end-stage kidney disease population, driven by traditional and non-traditional risk factors. Despite its prevalence, heart failure is difficult to diagnose in the dialysis population due to overlapping clinical presentations, limitations of investigations, and the impact on the cardiorenal axis. 'Foundation therapies' are the key medications which improve patient outcomes in heart failure with reduced ejection fraction and include beta-blockers, renin-angiotensin-aldosterone system inhibitors and sodium-glucose cotransporter-2 inhibitors. They are underutilised in the dialysis population due to the exclusion of chronic kidney disease patients from major trials and legitimate clinical concerns e.g. hyperkalaemia, intradialytic hypotension and residual kidney function preservation. A coordinated cardiorenal multidisciplinary approach can guide appropriate diagnostic considerations (biomarkers interpretation, imaging, addressing unique complications of kidney disease), optimise dialysis management (prescription length, frequency and ultrafiltration targets) and when at euvolaemia facilitate the stepwise introduction of appropriate foundation therapies.

C-terminal fragment of fibroblast growth factor 23 improves heart function in murine models of high intact fibroblast growth factor 23

Cardiovascular disease (CVD) is the major cause of death in chronic kidney disease (CKD) and is associated with high circulating fibroblast growth factor (FGF)23 levels. It is unresolved whether high circulating FGF23 is a mere biomarker or pathogenically contributes to cardiomyopathy. It is also unknown whether the C-terminal FGF23 peptide (cFGF23), a natural FGF23 antagonist proteolyzed from intact FGF23 (iFGF23), retards CKD progression and improves cardiomyopathy. We addressed these questions in three murine models with high endogenous FGF23 and cardiomyopathy. First, we examined wild-type (WT) mice with CKD induced by unilateral ischemia-reperfusion and contralateral nephrectomy followed by a high-phosphate diet. These mice were continuously treated with intraperitoneal implanted osmotic minipumps containing either iFGF23 protein to further escalate FGF23 bioactivity, cFGF23 peptide to block FGF23 signaling, vehicle, or scrambled peptide as negative controls. Exogenous iFGF23 protein given to CKD mice exacerbated pathological cardiac remodeling and CKD progression, whereas cFGF23 treatment improved heart and kidney function, attenuated fibrosis, and increased circulating soluble Klotho. WT mice without renal insult placed on a high-phosphate diet and homozygous Klotho hypomorphic mice, both of whom develop moderate CKD and clear cardiomyopathy, were treated with cFGF23 or vehicle. Mice treated with cFGF23 in both models had improved heart and kidney function and histopathology. Taken together, these data indicate high endogenous iFGF23 is not just a mere biomarker but pathogenically deleterious in CKD and cardiomyopathy. Furthermore, attenuation of FGF23 bioactivity by cFGF23 peptide is a promising therapeutic strategy to protect the kidney and heart from high FGF23 activity.NEW & NOTEWORTHY There is a strong correlation between cardiovascular morbidity and high circulating fibroblast growth factor 23 (FGF23) levels, but causality was never proven. We used a murine chronic kidney disease (CKD) model to show that intact FGF23 (iFGF23) is pathogenic and contributes to both CKD progression and cardiomyopathy. Blockade of FGF23 signaling with a natural proteolytic product of iFGF23, C-terminal FGF23, alleviated kidney and cardiac histology, and function in three separate murine models of high endogenous FGF23.

Factors associated with changes in echocardiographic parameters following kidney transplantation

BACKGROUND

Chronic kidney disease leads to cardiac remodelling of multifactorial origin known as "uraemic cardiomyopathy", the reversibility of which after kidney transplantation (KT) remains controversial. Our objectives were to assess, in the modern era, changes in echocardiographic parameters following KT and identify predictive clinical and biological factors associated with echocardiographic changes.

METHODS

One hundred six patients (mean age 48 ± 16, 73% male) who underwent KT at the University Hospital of Nancy between 2007 and 2018 were retrospectively investigated. Pre- and post-KT echocardiography findings (8.6 months before and 22 months after KT on average, respectively) were centralised, blind-reviewed and compared.

RESULTS

A majority of patients (60%) had either a left ventricular (LV) ejection fraction < 50%, at least moderately abnormal LV mass index or left atrial (LA) dilatation at pretransplanted echocardiography. After KT, LV remodelling and diastolic doppler indices did not significantly change whereas LA volume index (LAVI) increased (35.9 mL/m2 post-KT vs. 30.9 mL/m2 pre-KT, p = 0.006). Advancing age, cardiac valvular disease, delayed graft function, lower post-KT haemoglobin, and more severe post-KT hypertension were associated with higher LAVI after KT. Higher post-KT serum creatinine, more severe post-KT hypertension and lower pre-KT blood calcium levels were associated with a deterioration in LAVI after KT.

DISCUSSION/CONCLUSION

Adverse remodelling of the left atrial volume occurred after KT, predominantly in patients with lower pre-KT blood calcium, poorer graft function and post-KT hypertension. These results suggest that a better management of modifiable factors such as pre-KT hyperparathyroidism or post-KT hypertension could limit post-KT cardiac remodelling.

Echocardiographic manifestations in end-stage renal disease

End-stage renal disease (ESRD) is a common but profound clinical condition, and it is associated with extremely increased morbidity and mortality. ESRD can represent four major echocardiographic findings-myocardial hypertrophy, heart failure, valvular calcification, and pericardial effusion. Multiple factors interplay leading to these abnormalities, including pressure/volume overload, oxidative stress, and neurohormonal imbalances. Uremic cardiomyopathy is characterized by left ventricular (LV) hypertrophy and marked diastolic dysfunction. In ESRD patients on hemodialysis, LV geometry is changeable bidirectionally between concentric and eccentric hypertrophy, depending upon changes in corporal fluid volume and arterial pressure, which eventually results in a characteristic of LV systolic dysfunction. Speckle tracking echocardiography enabling to detect subclinical disease might help prevent future advancement to heart failure. Heart valve calcification also is common in ESRD, keeping in mind which progresses faster than expected. In a modern era, pericardial effusion observed in ESRD patients tends to result from volume overload, rather than pericarditis. In this review, we introduce and discuss those four echocardiography-assessed findings of ESRD, with which known and conceivable pathophysiologies for each are incorporated.

Chronic kidney disease associated cardiomyopathy: recent advances and future perspectives

PURPOSE OF REVIEW

Cardiomyopathy in chronic kidney disease (CKD) is a complex condition with multiple triggers and poor prognosis. This review provides an overview of recent advances in CKD-associated cardiomyopathy, with a focus on pathophysiology, newly discovered biomarkers and potential therapeutic targets.

RECENT FINDINGS

CKD is associated with a specific pattern of myocardial hypertrophy and fibrosis, resulting in diastolic and systolic dysfunction, and often triggered by nonatherosclerotic processes. Novel biomarkers, including amino-terminal type III procollagen peptide (PIIINP), carboxy-terminal type I procollagen peptide (PICP), FGF23, marinobufagenin, and several miRNAs, show promise for early detection and risk stratification. Treatment options for CKD-associated cardiomyopathy are limited. Sodium glucose cotransporter-2 inhibitors have been shown to reduce left ventricle hypertrophy and improve ejection fraction in individuals with diabetes and mild CKD, and are currently under investigation for more advanced stages of CKD. In hemodialysis patients calcimimetic etelcalcetide resulted in a significant reduction in left ventricular mass.

SUMMARY

CKD-associated cardiomyopathy is a common and severe complication in CKD. The identification of novel biomarkers may lead to future therapeutic targets. Randomized clinical trials in individuals with more advanced CKD would be well posed to expand treatment options for this debilitating condition.

Cardiac Magnetic Resonance Imaging Findings in Patients With Chronic Kidney Disease and End-Stage Kidney Disease: A Systematic Review and Meta-Analysis

In this systematic review and meta-analysis, we explored the utilization of cardiac magnetic resonance imaging (CMR) to detect fibrotic changes secondary to uremic cardiomyopathy during the early stages of chronic kidney disease (CKD) and in patients with end-stage kidney disease (ESKD). Uremic myocardial fibrosis can lead to arrhythmia and heart failure, and it is important to detect these changes. CMR offers a noninvasive way to characterize the severity of cardiac remodeling. A comprehensive search of multiple electronic databases was conducted. Studies were divided according to scanner field strength (1.5 or 3 Tesla). The random effects model was used to calculate the pooled mean, 95% confidence interval (CI), standard error, and standardized mean difference (SMD). The I2 statistic was used to assess the heterogeneity between study-specific estimates. The search retrieved 779 studies. From these, 20 studies met the inclusion criteria and had 642 CKD patients (mean age of 56.8 years; 65.2% males; mean estimated glomerular filtration rate (eGFR) of 33 mL/min/1.73 m2) and 658 ESKD patients on dialysis (mean age of 55.6 years; 63.3% males; mean dialysis duration of 3.47 years). CKD patients had an increased left ventricular mass index (LVMi) compared to controls, with an SMD of 0.37 (95% CI: 0.20-0.54; I2 0%; p-value <0.05). ESKD patients also had increased LVMi compared to controls, SMD 0.88 (95% CI: 0.35-1.41; I2 79.1%; p-value 0.001). Myocardial fibrosis assessment using T1 mapping showed elevated values; the SMD of native septal T1 values between CKD and controls was 1.099 (95% CI: 0.73-1.46; I2 33.6%; p-value <0.05), and the SMD of native septal T1 values between ESKD patients and controls was 1.12 (95% CI: 0.85-1.38; I2 33.69%; p-value <0.05). In conclusion, patients with CKD and ESKD with preserved left ventricular ejection fraction (LVEF) have higher LVMi and T1 values, indicating increased mass and fibrosis. T1 mapping can be used for the early detection of cardiomyopathy and as a risk stratification tool. Large, randomized trials are needed to confirm these findings and determine the effect of long-term dialysis on cardiac fibrosis.

Cardiomyopathy in chronic kidney disease: clinical features, biomarkers and the contribution of murine models in understanding pathophysiology

The cardiorenal syndrome (CRS) is described as a multi-organ disease encompassing bidirectionally heart and kidney. In CRS type 4, chronic kidney disease (CKD) leads to cardiac injury. Different pathological mechanisms have been identified to contribute to the establishment of CKD-induced cardiomyopathy, including a neurohormonal dysregulation, disturbances in the mineral metabolism and an accumulation of uremic toxins, playing an important role in the development of inflammation and oxidative stress. Combined, this leads to cardiac dysfunction and cardiac pathophysiological and morphological changes, like left ventricular hypertrophy, myocardial fibrosis and cardiac electrical changes. Given that around 80% of dialysis patients suffer from uremic cardiomyopathy, the study of cardiac outcomes in CKD is clinically highly relevant. The present review summarizes clinical features and biomarkers of CKD-induced cardiomyopathy and discusses underlying pathophysiological mechanisms recently uncovered in the literature. It discloses how animal models have contributed to the understanding of pathological kidney-heart crosstalk, but also provides insights into the variability in observed effects of CKD on the heart in different CKD mouse models, covering both "single hit" as well as "multifactorial hit" models. Overall, this review aims to support research progress in the field of CKD-induced cardiomyopathy.

Diagnosis of cardiovascular disease in patients with chronic kidney disease

Patients with chronic kidney disease (CKD) are at high risk of cardiovascular disease (CVD) and cardiovascular death. Identifying and monitoring cardiovascular complications and hypertension is important for managing patients with CKD or kidney failure and transplant recipients. Biomarkers of myocardial ischaemia, such as troponins and electrocardiography (ECG), have limited utility for diagnosing cardiac ischaemia in patients with advanced CKD. Dobutamine stress echocardiography, myocardial perfusion scintigraphy and dipyridamole stress testing can be used to detect coronary disease in these patients. Left ventricular hypertrophy and left ventricular dysfunction can be detected and monitored using various techniques with differing complexity and cost, including ECG, echocardiography, nuclear magnetic resonance, CT and myocardial scintigraphy. Atrial fibrillation and other major arrhythmias are common in all stages of CKD, and ambulatory heart rhythm monitoring enables precise time profiling of these disorders. Screening for cerebrovascular disease is only indicated in asymptomatic patients with autosomal dominant polycystic kidney disease. Standardized blood pressure is recommended for hypertension diagnosis and treatment monitoring and can be complemented by ambulatory blood pressure monitoring. Judicious use of these diagnostic techniques may assist clinicians in detecting the whole range of cardiovascular alterations in patients with CKD and enable timely treatment of CVD in this high-risk population.

The Impact of SGLT2 Inhibitors in the Heart and Kidneys Regardless of Diabetes Status

Chronic Kidney Disease (CKD) and Cardiovascular Disease (CVD) are two devastating diseases that may occur in nondiabetics or individuals with diabetes and, when combined, it is referred to as cardiorenal disease. The impact of cardiorenal disease on society, the economy and the healthcare system is enormous. Although there are numerous therapies for cardiorenal disease, one therapy showing a great deal of promise is sodium-dependent glucose cotransporter 2 (SGLT2) inhibitors. The SGLT family member, SGLT2, is often implicated in the pathogenesis of a range of diseases, and the dysregulation of the activity of SGLT2 markedly effects the transport of glucose and sodium across the luminal membrane of renal cells. Inhibitors of SGLT2 were developed based on the antidiabetic action initiated by inhibiting renal glucose reabsorption, thereby increasing glucosuria. Of great medical significance, large-scale clinical trials utilizing a range of SGLT2 inhibitors have demonstrated both metabolic and biochemical benefits via numerous novel mechanisms, such as sympathoinhibition, which will be discussed in this review. In summary, SGLT2 inhibitors clearly exert cardio-renal protection in people with and without diabetes in both preclinical and clinical settings. This exciting class of inhibitors improve hyperglycemia, high blood pressure, hyperlipidemia and diabetic retinopathy via multiple mechanisms, of which many are yet to be elucidated.

Dyslipidemia in Patients with Chronic Kidney Disease: An Updated Overview

Dyslipidemia is a potentially modifiable cardiovascular risk factor. Whereas the recommendations for the treatment target of dyslipidemia in the general population are being more and more rigorous, the 2013 Kidney Disease: Improving Global Outcomes clinical practice guideline for lipid management in chronic kidney disease (CKD) presented a relatively conservative approach with respect to the indication of lipid lowering therapy and therapeutic monitoring among the patients with CKD. This may be largely attributed to the lack of high-quality evidence derived from CKD population, among whom the overall feature of dyslipidemia is considerably distinctive to that of general population. In this review article, we cover the characteristic features of dyslipidemia and impact of dyslipidemia on cardiovascular outcomes in patients with CKD. We also review the current evidence on lipid lowering therapy to modify the risk of cardiovascular events in this population. We finally discuss the association between dyslipidemia and CKD progression and the potential strategy to delay the progression of CKD in relation to lipid lowering therapy.

Cardiac Imaging Biomarkers in Chronic Kidney Disease

Uremic cardiomyopathy (UC), the peculiar cardiac remodeling secondary to the systemic effects of renal dysfunction, is characterized by left ventricular (LV) diffuse fibrosis with hypertrophy (LVH) and stiffness and the development of heart failure and increased rates of cardiovascular mortality. Several imaging modalities can be used to obtain a non-invasive assessment of UC by different imaging biomarkers, which is the focus of the present review. Echocardiography has been largely employed in recent decades, especially for the determination of LVH by 2-dimensional imaging and diastolic dysfunction by pulsed-wave and tissue Doppler, where it retains a robust prognostic value; more recent techniques include parametric assessment of cardiac deformation by speckle tracking echocardiography and the use of 3D-imaging. Cardiac magnetic resonance (CMR) imaging allows a more accurate assessment of cardiac dimensions, including the right heart, and deformation by feature-tracking imaging; however, the most evident added value of CMR remains tissue characterization. T1 mapping demonstrated diffuse fibrosis in CKD patients, increasing with the worsening of renal disease and evident even in early stages of the disease, with few, but emerging, prognostic data. Some studies using T2 mapping highlighted the presence of subtle, diffuse myocardial edema. Finally, computed tomography, though rarely used to specifically assess UC, might provide incidental findings carrying prognostic relevance, including information on cardiac and vascular calcification. In summary, non-invasive cardiovascular imaging provides a wealth of imaging biomarkers for the characterization and risk-stratification of UC; integrating results from different imaging techniques can aid a better understanding of the physiopathology of UC and improve the clinical management of patients with CKD.

Hypertension and cardiomyopathy associated with chronic kidney disease: epidemiology, pathogenesis and treatment considerations

Chronic kidney disease (CKD) is a complex condition with a prevalence of 10-15% worldwide. An inverse-graded relationship exists between cardiovascular events and mortality with kidney function which is independent of age, sex, and other risk factors. The proportion of deaths due to heart failure and sudden cardiac death increase with progression of chronic kidney disease with relatively fewer deaths from atheromatous, vasculo-occlusive processes. This phenomenon can largely be explained by the increased prevalence of CKD-associated cardiomyopathy with worsening kidney function. The key features of CKD-associated cardiomyopathy are increased left ventricular mass and left ventricular hypertrophy, diastolic and systolic left ventricular dysfunction, and profound cardiac fibrosis on histology. While these features have predominantly been described in patients with advanced kidney disease on dialysis treatment, patients with only mild to moderate renal impairment already exhibit structural and functional changes consistent with CKD-associated cardiomyopathy. In this review we discuss the key drivers of CKD-associated cardiomyopathy and the key role of hypertension in its pathogenesis. We also evaluate existing, as well as developing therapies in the treatment of CKD-associated cardiomyopathy.

Cardiac-specific renalase overexpression alleviates CKD-induced pathological cardiac remodeling in mice

Introduction

CKD-induced pathological cardiac remodeling is characterized by myocardial hypertrophy and cardiac fibrosis. The available therapeutic options are limited, it is thus urgently needed to identify novel therapeutic targets. Renalase (RNLS) is a newly discovered protein secreted by the kidney and was found beneficial in many renal diseases. But whether it exerts protective effects on cardiac remodeling in CKD remains unclear.

Methods

RNLS knockout (KO) and wild-type (WT) mice were both used to build CKD models and the adeno-associated virus (AAV9) system was used to overexpress RNLS cardiac specifically. Echocardiography was performed to detect cardiac structural changes every 6 weeks until 18 weeks post-surgery. High throughput sequencing was performed to understand the underlying mechanisms and the effects of RNLS on cardiac fibroblasts were validated in vitro.

Results

Knockout of RNLS aggravated cardiac remodeling in CKD, while RNLS cardiac-specific overexpression significantly reduced left ventricular hypertrophy and cardiac fibrosis induced by CKD. The following RNA-sequencing analysis revealed that RNLS significantly downregulated the extracellular matrix (ECM) receptor interaction pathway, ECM organization, and several ECM-related proteins. GSEA results showed RNLS significantly downregulated several profibrotic biological processes of cardiac fibroblasts which were upregulated by CKD, including fibroblast proliferation, leukocyte migration, antigen presentation, cytokine production, and epithelial-mesenchymal transition (EMT). In vitro, we validated that RNLS reduced the primary cardiac fibroblast proliferation and α-SMA expression stimulated by TGF-β.

Conclusion

In this study, we examined the cardioprotective role of RNLS in CKD-induced cardiac remodeling. RNLS may be a potential therapeutic factor that exerts an anti-fibrotic effect in pathological cardiac remodeling.

A retrospective study of baseline peritoneal transport character and left ventricular hypertrophy in incident peritoneal dialysis patients: interrelationship and prognostic impacts

BACKGROUND

Left ventricular hypertrophy is associated with adverse outcomes among peritoneal dialysis patients. The aim of this study was to evaluate the prognostic impact of baseline left ventricular hypertrophy and its relationship with baseline peritoneal transfer characteristics in peritoneal dialysis patients.

METHODS

We enrolled 151 incident peritoneal dialysis patients to perform a multicentric retrospective cohort study since January 1, 2017 to January 31, 2021. Patients were grouped based on baseline dialysate-to-plasma creatinine ratio at 4 h as follows: low (<0.50), low average (0.5-0.64), high average (0.65-0.80) and high (≥0.81). Echocardiography and clinic data were recorded yearly. The Cox proportional hazards models and competing risk model were used to evaluate patients' survival. Generalized linear mixed models were performed to explore risk factors associated with left ventricular hypertrophy.

RESULTS

During a median follow-up period of 33 months (range, 16-48 months), 21 (13.9%) patients died, including 16 (10.60%) cardiovascular deaths. Controlling the competing risks of switching to hemodialysis, kidney transplantation and loss to follow-up, baseline left ventricular hypertrophy was an independent risk factor for all-cause mortality (subdistribution hazard ratio, 2.645; 95% confidence interval, 1.156-6.056; p = 0.021). Baseline high and high average transport status were positively related to left ventricular mass index and left atrium diameter 2 years after PD initiation.

CONCLUSION

Baseline fast peritoneal solute transport rate may be an effect factor for aggravating left ventricular hypertrophy which predicted poor outcomes for peritoneal dialysis patients. The findings offered important ideas for further prospective intervention study.

Cardiac magnetic resonance imaging parameters show association between myocardial abnormalities and severity of chronic kidney disease

BACKGROUND

Chronic kidney disease patients have increased risk of cardiovascular abnormalities. This study investigated the relationship between cardiovascular abnormalities and the severity of chronic kidney disease using cardiac magnetic resonance imaging.

METHODS

We enrolled 84 participants with various stages of chronic kidney disease (group I: stages 1-3, n = 23; group II: stages 4-5, n = 20; group III: hemodialysis patients, n = 41) and 32 healthy subjects. The demographics and biochemical parameters of the study subjects were evaluated. All subjects underwent non-contrast cardiac magnetic resonance scans. Myocardial strain, native T1, and T2 values were calculated from the scanning results. Analysis of covariance was used to compare the imaging parameters between group I-III and the controls.

RESULTS

The left ventricular ejection fraction (49 vs. 56%, p = 0.021), global radial strain (29 vs. 37, p = 0.019) and global circumferential strain (-17.4 vs. -20.6, p < 0.001) were significantly worse in group III patients compared with the controls. Furthermore, the global longitudinal strain had a significant decline in group II and III patients compared with the controls (-13.7 and -12.9 vs. -16.2, p < 0.05). Compared with the controls, the native T1 values were significantly higher in group II and III patients (1,041 ± 7 and 1,053 ± 6 vs. 1,009 ± 6, p < 0.05), and T2 values were obviously higher in group I-III patients (49.9 ± 0.6 and 53.2 ± 0.7 and 50.1 ± 0.5 vs. 46.6 ± 0.5, p < 0.001). The advanced chronic kidney disease stage showed significant positive correlation with global radial strain (r = 0.436, p < 0.001), global circumferential strain (r = 0.386, p < 0.001), native T1 (r = 0.5, p < 0.001) and T2 (r = 0.467, p < 0.001) values. In comparison with the group II patients, hemodialysis patients showed significantly lower T2 values (53.2 ± 0.7 vs. 50.1 ± 0.5, p = 0.002), but no significant difference in T1 values (1,041 ± 7 vs. 1,053 ± 6).

CONCLUSIONS

Our study showed that myocardial strain, native T1, and T2 values progressively got worse with advancing chronic kidney disease stage. The increased T1 values and decreased T2 values of hemodialysis patients might be due to increasing myocardial fibrosis but with reduction in oedema following effective fluid management.

TRIAL REGISTRATION NUMBER

ChiCTR2100053561 (http://www.chictr.org.cn/edit.aspx?pid=139737&htm=4).

High-flow arteriovenous fistula and myocardial fibrosis in hemodialysis patients with non-contrast cardiac magnetic resonance imaging

Background

The role of high-flow arteriovenous fistula (AVF) in cardiovascular morbidity in hemodialysis (HD) patients is very likely under-recognized. We assessed the relationship between high access flow (Qa) and myocardial fibrosis in HD patients.

Methods

Myocardial fibrosis was assessed by native T1 relaxation times on non-contrast cardiac magnetic resonance imaging and a potential marker of fibrosis. Serum levels of galectin-3, N-terminal pro-B-type natriuretic peptide (NT-proBNP), and monocyte chemoattractant protein 1 (MCP-1) were measured in 101 HD patients who underwent regular monitoring of AVF Qa. A high-flow AVF was defined as a Qa >2 L/min.

Results

Hemodialysis patients showed significantly higher galectin-3 value and increased T1 relaxation time compared to healthy volunteers, suggesting increased myocardial fibrosis in uremic cardiomyopathy. In HD patients, 20 (19.8%) had a Qa > 2L/min, and they had significantly higher cardiac output, cardiac index, left ventricular mass, and increased T1 times than those with a Qa ≤ 2 L/min. Also, serum galectin-3 and NT-proBNP levels were much higher in the high Qa group, indicating a close relationship between the high Qa, increased myocardial fibrosis, and the risk of heart failure (HF) in HD patients. It is interesting that a higher AVF Qa for myocardial fibrosis was independent of several traditional cardiovascular risk factors as well as serum levels of NT-proBNP and MCP-1.

Conclusions

A supra-physiologically high Qa can be related to myocardial fibrosis and increased risk of HF in HD patients. Regular Qa monitoring could allow early detection of a high-flow AVF that could arise cardiac complications.

The Diabetic Cardiorenal Nexus

The end-stage of the clinical combination of heart failure and kidney disease has become known as cardiorenal syndrome. Adverse consequences related to diabetes, hyperlipidemia, obesity, hypertension and renal impairment on cardiovascular function, morbidity and mortality are well known. Guidelines for the treatment of these risk factors have led to the improved prognosis of patients with coronary artery disease and reduced ejection fraction. Heart failure hospital admissions and readmission often occur, however, in the presence of metabolic, renal dysfunction and relatively preserved systolic function. In this domain, few advances have been described. Diabetes, kidney and cardiac dysfunction act synergistically to magnify healthcare costs. Current therapy relies on improving hemodynamic factors destructive to both the heart and kidney. We consider that additional hemodynamic solutions may be limited without the use of animal models focusing on the cardiomyocyte, nephron and extracellular matrices. We review herein potential common pathophysiologic targets for treatment to prevent and ameliorate this syndrome.

Impact of left ventricular hypertrophy on clinical outcomes in patients with dialysis: a single-center study in Japan

PURPOSE

Left ventricular hypertrophy (LVH) is a well-known risk factor for poor clinical outcomes in patients undergoing dialysis. However, little evidence supports the above notion in Japan, and the influence of subtypes of LVH on prognosis.

METHODS

We investigated 367 patients undergoing dialysis who underwent routine echocardiographic examinations between April and September 2018. LVH was defined as any LV mass ≥ 115 g/m² in men and ≥ 95 g/m² in women obtained by echocardiography. The primary endpoint was a composite outcome including all-cause death, admission due to heart failure, and ischemic heart event or stroke. LVH was divided into subtype-groups according to eccentric hypertrophy or concentric hypertrophy, and with and without hypertension.

RESULTS

LVH was observed in 171 (47%) patients. The primary endpoint was observed in 58 patients (16%) during the median follow-up period of 500 days. Multivariable Cox regression analyses identified four independent risk factors for the primary endpoint: age, pulse rate, serum albumin level, and LV mass index (per 10-g/m² increase; hazard ratio: 1.12, 95% confidence interval: 1.06-1.18, P < 0.001). Kaplan-Meier analyses demonstrated that patients with LVH had a worse prognosis than those without LVH in terms of the primary endpoint (log-rank P < 0.001). The incidence of the primary outcome was not significantly different between patients with eccentric or concentric hypertrophy, and between LVH patients with and without hypertension.

CONCLUSION

Japanese patients with LVH undergoing dialysis had a worse prognosis than those without LVH in terms of the composite clinical endpoint.

Time-dependent cardiac structural and functional changes after kidney transplantation: a multi-parametric cardiac magnetic resonance study

OBJECTIVES

To map time-dependent cardiac structural and functional change patterns after renal transplantation (KT) using cardiac magnetic resonance (CMR).

METHODS

Fifty-three patients with pre-KT and post-KT CMR exams were retrospectively analyzed. Patients were divided into three groups according to the time of post-KT CMR: group 1 (3 months post-KT, n = 16), group 2 (6 months post-KT, n = 21), and group 3 (over 9 months post-KT, n = 16). Twenty-one age- and sex-matched healthy controls (HC) were recruited for the study. CMR-derived left ventricular (LV) volumes, LV mass index (LVMi), LV ejection fraction (LVEF), global radial strain (GRS), global circumferential strain (GCS), global longitudinal strain (GLS), and native T1 value were compared. The association between the changes of CMR parameters was assessed.

RESULTS

LVMi post-KT decreased in groups 2 (p < 0.001) and 3 (p = 0.004) but both groups had higher LVMi values compared to HC (both p < 0.001). GLS post-KT was decreased in group 1 (p = 0.021), but slightly increased in group 2 (p = 0.728) and group 3 (p = 0.100) without significant difference. GLS post-KT in group 3 was not different from HC (p = 0.104). LVEF, GRS, and GCS post-KT in groups 2 and 3 significantly increased and showed no significant difference from HC. The post-KT native T1 value in all three groups significantly decreased; however, no group showed any significant difference from HC. The change of LVEF was associated with the change of GCS, GRS, and GLS.

CONCLUSIONS

Although GRS, GCS, GLS, and native T1 values reversed to normal level, LVMi remained impaired in median 14 months after KT.

KEY POINTS

• Kidney transplantation has favorable effects on cardiac structure and function. • In a median 14 months of follow-up after KT, left ventricle strain and native T1 value reversed to normal level while LV mass index (LVMi) did not. Left ventricular hypertrophy may help to explain why KT recipients are still at increased cardiovascular risk. • The reason for the decrease of native T1 value after KT may be more than myocardial fibrosis and needs to be further studied.

Myocardial Cytoskeletal Adaptations in Advanced Kidney Disease

Background The myocardial cytoskeleton functions as the fundamental framework critical for organelle function, bioenergetics and myocardial remodeling. To date, impairment of the myocardial cytoskeleton occurring in the failing heart in patients with advanced chronic kidney disease has been largely undescribed. Methods and Results We conducted a 3-arm cross-sectional cohort study of explanted human heart tissues from patients who are dependent on hemodialysis (n=19), hypertension (n=10) with preserved renal function, and healthy controls (n=21). Left ventricular tissues were subjected to pathologic examination and next-generation RNA sequencing. Mechanistic and interference RNA studies utilizing in vitro human cardiac fibroblast models were performed. Left ventricular tissues from patients undergoing hemodialysis exhibited increased myocardial wall thickness and significantly greater fibrosis compared with hypertension patients (P<0.05) and control (P<0.01). Transcriptomic analysis revealed that the focal adhesion pathway was significantly enriched in hearts from patients undergoing hemodialysis. Hearts from patients undergoing hemodialysis exhibited dysregulated components of the focal adhesion pathway including reduced β-actin (P<0.01), β-tubulin (P<0.01), vimentin (P<0.05), and increased expression of vinculin (P<0.05) compared with controls. Cytoskeletal adaptations in hearts from the hemodialysis group were associated with impaired mitochondrial bioenergetics, including dysregulated mitochondrial dynamics and fusion, and loss of cell survival pathways. Mechanistic studies revealed that cytoskeletal changes can be driven by uremic and metabolic abnormalities of chronic kidney disease, in vitro. Furthermore, focal adhesion kinase silencing via interference RNA suppressed major cytoskeletal proteins synergistically with mineral stressors found in chronic kidney disease in vitro. Conclusions Myocardial failure in advanced chronic kidney disease is characterized by impairment of the cytoskeleton involving disruption of the focal adhesion pathway, mitochondrial failure, and loss of cell survival pathways.

T1 and T2 Mapping in Uremic Cardiomyopathy: An Update

Uremic cardiomyopathy (UC) is the cardiac remodelling that occurs in patients with chronic kidney disease (CKD). It is characterised by a left ventricular (LV) hypertrophy phenotype, diastolic dysfunction and generally preserved LV ejection fraction. UC has a major role mediating the increased rate of cardiovascular events, especially heart failure related, observed in patients with CKD. Recently, the use of T1 and T2 mapping techniques on cardiac MRI has expanded the ability to characterise cardiac involvement in CKD. Native T1 mapping effectively tracks the progression of interstitial fibrosis in UC, whereas T2 mapping analysis suggests the contribution of myocardial oedema, at least in a subgroup of patients. Both T1 and T2 increased values were related to worsening clinical status, myocardial injury and B-type natriuretic peptide release. Studies investigating the prognostic relevance and histology validation of mapping techniques in CKD are awaited.

Risk for subsequent hypertension and cardiovascular disease after living kidney donation: is it clinically relevant?

The first successful live donor kidney transplant was performed in 1954. Receiving a kidney transplant from a live kidney donor remains the best option for increasing both life expectancy and quality of life in patients with end-stage kidney disease. However, ever since 1954, there have been multiple questions raised on the ethics of live kidney donation in terms of negative impacts on donor life expectancy. Given the close relationship between reduced kidney function in patients with chronic kidney disease (CKD) and hypertension, cardiovascular disease and cardiovascular mortality, information on the impact of kidney donation on these is particularly relevant. In this article, we review the existing evidence, focusing on the more recent studies on the impact of kidney donation on all-cause mortality, cardiovascular mortality, cardiovascular disease and hypertension, as well as markers of cardiovascular damage including arterial stiffness and uraemic cardiomyopathy. We also discuss the similarities and differences between the pathological reduction in renal function that occurs in CKD, and the reduction in renal function that occurs because of a donor nephrectomy. Kidney donors perform an altruistic act that benefits individual patients as well as the wider society. They deserve to have high-quality evidence on which to make informed decisions.

Global longitudinal strain by feature-tracking cardiovascular magnetic resonance imaging predicts mortality in patients with end-stage kidney disease

Background

Patients with end-stage kidney disease (ESKD) are at increased risk of premature death, with cardiovascular disease being the predominant cause of death. We hypothesized that left ventricular global longitudinal strain (LV-GLS) measured by feature-tracking cardiovascular magnetic resonance imaging (CMRI) would be associated with all-cause mortality in patients with ESKD.

Methods

A pooled analysis of CMRI studies in patients with ESKD acquired within a single centre between 2002 and 2016 was carried out. CMR parameters including LV ejection fraction (LVEF), LV mass index, left atrial emptying fraction (LAEF) and LV-GLS were measured. We tested independent associations of CMR parameters with survival using a multivariable Cox model.

Results

Among 215 patients (mean age 54 years, 62% male), mortality was 53% over a median follow-up of 5 years. The median LVEF was 64.7% [interquartile range (IQR) 58.5-70.0] and the median LV-GLS was -15.3% (IQR -17.24 to -13.6). While 90% of patients had preserved LVEF (>50%), 58% of this group had abnormal LV-GLS (>-16%). On multivariable Cox regression, age {hazard ratio [HR] 1.04 [95% confidence interval (CI) 1.02-1.05]}, future renal transplant [HR 0.29 (95% CI 0.17-0.47)], LAEF [HR 0.98 (95% CI 0.96-1.00)] and LV-GLS [HR 1.08 (95% CI 1.01-1.16)] were independently associated with mortality.

Conclusions

In this cohort of patients with ESKD, LV-GLS on feature-tracking CMRI and LAEF was associated with all-cause mortality, independent of baseline clinical variables and future renal transplantation. This effect was present even when >90% of the cohort had normal LVEF. Using LV-GLS instead of LVEF to diagnose cardiac dysfunction in patients with ESKD could result in a major advance in our understanding of cardiovascular disease in ESKD.

Myocardial changes on 3T cardiovascular magnetic resonance imaging in response to haemodialysis with fluid removal

BACKGROUND

Mapping of left ventricular (LV) native T1 is a promising non-invasive, non-contrast imaging biomarker. Native myocardial T1 times are prolonged in patients requiring dialysis, but there are concerns that the dialysis process and fluctuating fluid status may confound results in this population. We aimed to assess the changes in cardiac parameters on 3T cardiovascular magnetic resonance (CMR) before and after haemodialysis, with a specific focus on native T1 mapping.

METHODS

This is a single centre, prospective observational study in which maintenance haemodialysis patients underwent CMR before and after dialysis (both scans within 24 h). Weight measurement, bio-impedance body composition monitoring, haemodialysis details and fluid intake were recorded. CMR protocol included cine imaging and mapping native T1 and T2.

RESULTS

Twenty-six participants (16 male, 65 ± 9 years) were included in the analysis. The median net ultrafiltration volume on dialysis was 2.3 L (IQR 1.8, 2.5), resulting in a median weight reduction at post-dialysis scan of 1.35 kg (IQR 1.0, 1.9), with a median reduction in over-hydration (as measured by bioimpedance) of 0.75 L (IQR 0.5, 1.4). Significant reductions were observed in LV end-diastolic volume (- 25 ml, p = 0.002), LV stroke volume (- 13 ml, p = 0.007), global T1 (21 ms, p = 0.02), global T2 (- 1.2 ms, p = 0.02) following dialysis. There was no change in LV mass (p = 0.35), LV ejection fraction (p = 0.13) or global longitudinal strain (p = 0.22). On linear regression there was no association between baseline over-hydration (as defined by bioimpedance) and global native T1 or global T2, nor was there an association between the change in over-hydration and the change in these parameters.

CONCLUSIONS

Acute changes in cardiac volumes and myocardial native T1 are detectable on 3T CMR following haemodialysis with fluid removal. The reduction in global T1 suggests that the abnormal native T1 observed in patients on haemodialysis is not entirely due to myocardial fibrosis.

A pilot randomised controlled trial of a structured, home-based exercise programme on cardiovascular structure and function in kidney transplant recipients: the ECSERT study design and methods

BACKGROUND

Cardiovascular disease (CVD) is a major cause of morbidity and mortality in kidney transplant recipients (KTRs). CVD risk scores underestimate risk in this population as CVD is driven by clustering of traditional and non-traditional risk factors, which lead to prognostic pathological changes in cardiovascular structure and function. While exercise may mitigate CVD in this population, evidence is limited, and physical activity levels and patient activation towards exercise and self-management are low. This pilot study will assess the feasibility of delivering a structured, home-based exercise intervention in a population of KTRs at increased cardiometabolic risk and evaluate the putative effects on cardiovascular structural and functional changes, cardiorespiratory fitness, quality of life, patient activation, healthcare utilisation and engagement with the prescribed exercise programme.

METHODS AND ANALYSIS

Fifty KTRs will be randomised 1:1 to: (1) the intervention; a 12week, home-based combined resistance and aerobic exercise intervention; or (2) the control; usual care. Intervention participants will have one introductory session for instruction and practice of the recommended exercises prior to receiving an exercise diary, dumbbells, resistance bands and access to instructional videos. The study will evaluate the feasibility of recruitment, randomisation, retention, assessment procedures and the intervention implementation. Outcomes, to be assessed prior to randomisation and postintervention, include: cardiac structure and function with stress perfusion cardiac MRI, cardiorespiratory fitness, physical function, blood biomarkers of cardiometabolic health, quality of life and patient activation. These data will be used to inform the power calculations for future definitive trials.

ETHICS AND DISSEMINATION

The protocol was reviewed and given favourable opinion by the East Midlands-Nottingham 2 Research Ethics Committee (reference: 19/EM/0209; 14 October 2019). Results will be published in peer-reviewed academic journals and will be disseminated to the patient and public community via social media, newsletter articles and presentations at conferences.

TRIAL REGISTRATION NUMBER

NCT04123951.

Aortic Arch Calcification and Cardiomegaly Are Associated with Overall and Cardiovascular Mortality in Hemodialysis Patients

Patients with end-stage renal disease have a higher risk of cardiovascular morbidity and mortality. In this study, we investigated the predictive ability of a combination of cardiothoracic ratio (CTR) and aortic arch calcification (AoAC) for overall and cardiovascular mortality in patients receiving hemodialysis. We also evaluated the predictive power of AoAC and CTR for clinical outcomes. A total of 365 maintenance hemodialysis patients were included, and AoAC and CTR were measured using chest radiography at enrollment. We stratified the patients into four groups according to a median AoAC score of three and CTR of 50%. Multivariable Cox proportional hazards analysis was used to identify the risk factors of mortality. The predictive performance of the model for clinical outcomes was assessed using the χ2 test. Multivariable analysis showed that, compared to the AoAC < 3 and CTR < 50% group, the AoAC ≥ 3 and CTR < 50% group (hazard ratio [HR], 4.576; p < 0.001), and AoAC ≥ 3 and CTR ≥ 50% group (HR, 5.912; p < 0.001) were significantly associated with increased overall mortality. In addition, the AoAC < 3 and CTR ≥ 50% (HR, 3.806; p = 0.017), AoAC ≥ 3 and CTR < 50% (HR, 4.993; p = 0.002), and AoAC ≥ 3 and CTR ≥ 50% (HR, 8.614; p < 0.001) groups were significantly associated with increased cardiovascular mortality. Furthermore, adding AoAC and CTR to the basic model improved the predictive ability for overall and cardiovascular mortality. The patients who had a high AoAC score and cardiomegaly had the highest overall and cardiovascular mortality among the four groups. Furthermore, adding AoAC and CTR improved the predictive ability for overall and cardiovascular mortality in the hemodialysis patients.

Non-high-density lipoprotein cholesterol and mortality among peritoneal dialysis patients

BACKGROUND

The association between non-high-density lipoprotein cholesterol (non-HDL-C) and mortality in patients undergoing peritoneal dialysis (PD) is unclear.

OBJECTIVE

The aim of this study was to evaluate the association of non-HDL-C with cardiovascular (CV) and all-cause mortality in PD patients.

METHODS

We conducted a prospective cohort study. A total of 1,616 incident PD patients from a single PD center in South China were followed for a median of 47.6 months. The independent association of non-HDL-C with CV and all-cause mortality was evaluated by a Cox regression analysis.

RESULTS

During the follow-up period, 508 (31.4%) patients died, of which 249 (49.0%) were due to CV events. Atherosclerotic CV mortality accounted for 59.8% of CV mortality. In multivariable models, for 1-SD increase in non-HDL-C level, the hazard ratios (HRs) for CV and all-cause mortality were 1.52  [95% confidence interval (CI), 1.32-1.75; P < 0.001)] and 1.24 (95% CI, 1.12-1.39; P < 0.001), respectively. Furthermore, non-HDL-C was positively associated with atherosclerotic CV mortality (HR, 1.29; 95% CI, 1.09-1.52; P = 0.004) but not associated with nonatherosclerotic CV mortality (HR, 0.79; 95% CI, 0.59-1.05; P = 0.108). The quartile analyses showed a similar pattern to the continuous variable analyses of non-HDL-C levels for CV and all-cause mortality but did not demonstrate statistical significance for atherosclerotic or nonatherosclerotic CV mortality.

CONCLUSION

An elevated non-HDL-C level was independently associated with an increased risk of CV mortality, especially atherosclerotic CV mortality, and all-cause mortality in incident PD patients.

Elevated circulating fibrocyte levels in hemodialysis-dependent end-stage renal disease patients

INTRODUCTION

Numerous studies have demonstrated that end-stage renal disease (ESRD) patients undergoing hemodialysis (HD) have high myocardial fibrosis (MF) levels. Circulating fibrocytes are bone marrow-derived circulating mesenchymal progenitors, and new evidence suggests a vital role for fibrocytes in the development of MF. This study aimed to investigate whether fibrocyte levels are elevated in patients undergoing HD and its influence factors.

METHODS

We carried out a flow cytometry analysis to measure the proportion of peripheral blood circulating fibrocytes in a cohort of 126 healthy control individuals and 161 subjects with HD. Cardiac function and morphology were assessed by electrocardiogram and transthoracic echocardiogram.

FINDINGS

Compared to healthy controls, individuals with ESRD had significantly higher levels of circulating fibrocytes. There was a strong correlation between the frequency of fragmented QRS (fQRS) and circulating fibrocytes in HD patients. Furthermore, higher fibrocytes correlated to increasing age, dialysis age, left ventricular mass index (LVMI), left ventricular ejection fraction (LVEF), and hypertension complication. On multivariate analysis, the dialysis age [odds ratio (OR) 1.011, 95% confidence interval (CI) 1.003-1.019, p = 0.006], LVMI (OR 1.012, 95% CI 1.002-1.022, p = 0.016), hypertension (OR 4.303, 95% CI 1.129-16.406, p = 0.033), and fQRS (OR 2.439, 95% CI 1.049-5.262, p = 0.038) were significant independent predictors of fibrocytes percentage.

DISCUSSION

We concluded that bone marrow-derived circulating fibrocytes were significantly increased in ESRD patients with HD compared with controls. Our data suggested that these cells might play essential roles during MF in HD patients.

Feature-tracking cardiac magnetic resonance left ventricular global longitudinal strain improves 6 months after kidney transplantation associated with reverse remodeling, not myocardial tissue characteristics

To determine whether left ventricular (LV) global longitudinal strain (GLS) measured by feature-tracking (FT) cardiac magnetic resonance (CMR) improves after kidney transplantation (KT) and to analyze associations between LV GLS, reverse remodeling and myocardial tissue characteristics. This is a prospective single-center cohort study of kidney transplant recipients who underwent two CMR examinations in a 3T scanner, including cines, tagging, T1 and T2 mapping. The baseline exam was done up to 10 days after transplantation and the follow-up after 6 months. Age and sex-matched healthy controls were also studied for comparison. A total of 44 patients [mean age 50 ± 11 years-old, 27 (61.4%) male] completed the two CMR exams. LV GLS improved from - 13.4% ± 3.0 at baseline to - 15.2% ± 2.7 at follow-up (p < 0.001), but remained impaired when compared with controls (- 17.7% ± 1.5, p = 0.007). We observed significant correlation between improvement in LV GLS with reductions of left ventricular mass index (r = 0.356, p = 0.018). Improvement in LV GLS paralleled improvements in LV stroke volume index (r = - 0.429, p = 0.004), ejection fraction (r = - 0.408, p = 0.006), global circumferential strain (r = 0.420, p = 0.004) and global radial strain (r = - 0.530, p = 0.002). There were no significant correlations between LV GLS, native T1 or T2 measurements (p > 0.05). In this study, we demonstrated that LV GLS measured by FT-CMR improves 6 months after KT in association with reverse remodeling, but not native T1 or T2 measurements.

Differences in native T1 and native T2 mapping between patients on hemodialysis and control subjects

PURPOSE

Myocardial native T1 is a potential measure of myocardial fibrosis, but concerns remain over the potential influence of myocardial edema to increased native T1 signal in subjects prone to fluid overload. This study describes differences in native T2 (typically raised in states of myocardial edema) and native T1 times in patients on hemodialysis by comparing native T1 and native T2 times between subjects on hemodialysis to an asymptomatic control group. Reproducibility of these sequences was tested.

METHODS

Subjects were recruited prospectively and underwent 3 T-cardiac MRI with acquisition of native T1 and native T2 maps. Between group differences in native T1 and T2 maps were assessed using one-way ANOVAs. 30 subjects underwent test-retest scans within a week of their original scan to define sequence reproducibility.

RESULTS

261 subjects completed the study (hemodialysis n = 124, control n = 137). Native T1 times were significantly increased in subjects on hemodialysis compared to control subjects (1259 ms ± 51 vs 1212 ms ± 37, p < 0.01). There was no difference in native T2 times between subjects on hemodialysis and control subjects (39.5 ms ± 2.5 vs 39.5 ms ± 2.3, p = 0.9). These differences were unchanged after adjustment for relevant baseline differences (age, sex and hemoglobin). Inter-study reproducibility for native T1 and T2 mapping was excellent (coefficient of variability 0.9 % and 2.6 % respectively).

CONCLUSIONS

The increased native T1 signal demonstrated in subjects on hemodialysis occurs independently of differences in native T2 and the two parameters are not orthogonal. Elevated native T1 in patients on hemodialysis may be driven by water related to myocardial fibrosis rather than edema from volume overload.

A randomized controlled trial to investigate the effects of intra-dialytic cycling on left ventricular mass

Cardiovascular disease is the leading cause of death for patients receiving hemodialysis. Since exercise mitigates many risk factors which drive cardiovascular disease for these patients, we assessed effects of a program of intra-dialytic cycling on left ventricular mass and other prognostically relevant measures of cardiovascular disease as evaluated by cardiac MRI (the CYCLE-HD trial). This was a prospective, open-label, single-blinded cluster-randomized controlled trial powered to detect a 15g difference in left ventricular mass measured between patients undergoing a six-month program of intra-dialytic cycling (exercise group) and patients continuing usual care (control group). Pre-specified secondary outcomes included measures of myocardial fibrosis, aortic stiffness, physical functioning, quality of life and ventricular arrhythmias. Outcomes were analyzed as intention-to-treat according to a pre-specified statistical analysis plan. Initially, 130 individuals were recruited and completed baseline assessments (65 each group). Ultimately, 101 patients completed the trial protocol (50 control group and 51 exercise group). The six-month program of intra-dialytic cycling resulted in a significant reduction in left ventricular mass between groups (-11.1g; 95% confidence interval -15.79, -6.43), which remained significant on sensitivity analysis (missing data imputed) (-9.92g; 14.68, -5.16). There were significant reductions in both native T1 mapping and aortic pulse wave velocity between groups favoring the intervention. There was no increase in either ventricular ectopic beats or complex ventricular arrhythmias as a result of exercise with no significant effect on physical function or quality of life. Thus, a six-month program of intradialytic cycling reduces left ventricular mass and is safe, deliverable and well tolerated.

The cardiovascular determinants of physical function in patients with end-stage kidney disease on haemodialysis

Patients with end-stage kidney disease (ESKD) are often sedentary and decreased functional capacity associates with mortality. The relationship between cardiovascular disease (CVD) and physical function has not been fully explored. Understanding the relationships between prognostically relevant measures of CVD and physical function may offer insight into how exercise interventions might target specific elements of CVD. 130 patients on haemodialysis (mean age 57 ± 15 years, 73% male, dialysis vintage 1.3 years (0.5, 3.4), recruited to the CYCLE-HD trial (ISRCTN11299707), underwent cardiovascular phenotyping with cardiac MRI (left ventricular (LV) structure and function, pulse wave velocity (PWV) and native T1 mapping) and cardiac biomarker assessment. Participants completed the incremental shuttle walk test (ISWT) and sit-to-stand 60 (STS60) as field-tests of physical function. Linear regression models identified CV determinants of physical function measures, adjusted for age, gender, BMI, diabetes, ethnicity and systolic blood pressure. Troponin I, PWV and global native T1 were univariate determinants of ISWT and STS60 performance. NT pro-BNP was a univariate determinant of ISWT performance. In multivariate models, NT pro-BNP and global native T1 were independent determinants of ISWT and STS60 performance. LV ejection fraction was an independent determinant of ISWT distance. However, age and diabetes had the strongest relationships with physical function. In conclusion, NT pro-BNP, global native T1 and LV ejection fraction were independent CV determinants of physical function. However, age and diabetes had the greatest independent influence. Targeting diabetic care may ameliorate deconditioning in these patients and a multimorbidity approach should be considered when developing exercise interventions.

Changes in left ventricular structure and function associated with renal transplantation: a systematic review and meta-analysis

Aims

This study aimed to examine if the cardiac changes associated with uraemic cardiomyopathy are reversed by renal transplantation.

Methods and results

MEDLINE, Embase, OpenGrey, and the Cochrane Library databases were searched from 1950 to March 2020. The primary outcome measure was left ventricular mass index. Secondary outcome measures included left ventricular dimensions and measures of diastolic and systolic function. Studies were included if they used any imaging modality both before and after successful renal transplantation. Data were analysed through meta‐analysis approaches. Weight of evidence was assessed through the Grading of Recommendations Assessment, Development and Evaluation system. Twenty‐three studies used echocardiography, and three used cardiac magnetic resonance imaging as their imaging modality. The methodological quality of the evidence was generally poor. Four studies followed up control groups, two using cardiac magnetic resonance imaging and two using echocardiography. Meta‐analysis of these studies indicated that there was no difference in left ventricular mass index between groups following transplantation {standardized mean difference −0.07 [95% confidence interval (CI) −0.41 to 0.26]; P = 0.67}. There was also no difference observed in left ventricular ejection fraction [mean difference 0.39% (95% CI −4.09% to 4.87%); P = 0.86] or left ventricular end‐diastolic volume [standardized mean difference −0.24 (95% CI −0.94 to 0.45); P = 0.49]. Inconsistent reporting of changes in diastolic dysfunction did not allow for any meaningful analysis or interpretation.

Conclusions

The evidence does not support the notion that uraemic cardiomyopathy is reversible by renal transplantation. However, the evidence is limited by methodological weaknesses, which should be considered when interpreting these findings.

A Personalized Approach to Chronic Kidney Disease and Cardiovascular Disease: JACC Review Topic of the Week

Cardiovascular disease is the most common cause of death in patients with end-stage renal disease (ESRD). The initiation of dialysis for treatment of ESRD exacerbates chronic electrolyte and hemodynamic perturbations. Rapid large shifts in effective intravascular volume and electrolyte concentrations ultimately lead to subendocardial ischemia, increased left ventricular wall mass, and diastolic dysfunction, and can precipitate serious arrhythmias through a complex pathophysiological process. These factors, unique to advanced kidney disease and its treatment, increase the overall incidence of acute coronary syndrome and sudden cardiac death. To date, risk prediction models largely fail to incorporate the observed cardiovascular mortality in the CKD population; however, multimodality imaging may provide an additional prognostication and risk stratification. This comprehensive review discusses the cardiovascular risks associated with hemodialysis, and explores the pathophysiology and the novel utilization of multimodality imaging in CKD to promote a personalized approach for these patients with implications for future research.

Identification of cardiovascular abnormalities by multiparametric magnetic resonance imaging in end-stage renal disease patients with preserved left ventricular ejection fraction

OBJECTIVES

Our study aimed to evaluate myocardial strain and tissue characteristics by multiparametric cardiovascular magnetic resonance (CMR) imaging in end-stage renal disease (ESRD) patients on peritoneal dialysis with preserved left ventricular ejection fraction (LVEF).

METHODS

ESRD patients on peritoneal dialysis with echocardiographic LVEF > 50% and age- and sex-matched healthy volunteers underwent multiparametric CMR at 3 T. LV function, LV myocardial native T1 and T2, and biventricular strain were measured and compared between the patients and controls. Associations of LV myocardial mass index (LVMI) with tissue characterization and strain were evaluated by multiple linear regression.

RESULTS

A total of 65 subjects (42 healthy volunteers and 23 ESRD patients) were enrolled. ESRD group demonstrated larger LVMI, higher native T1 and T2 (1301.9 ± 30.6 ms, 44.6 ± 2.6 ms) than those of the control group (1255.8 ± 45.2 ms, 40.5 ± 1.6 ms; both p < 0.001). Decreased LV strain and increased right ventricular circumferential strain were observed in the ESRD group. In ESRD patients with normal diastolic function on echocardiography, native T1 and T2 values were higher than those of the control group (p = 0.006, p = 0.001). Increased LVMI was associated with increased native T1 (p = 0.001) and T2 value (p < 0.001) after adjusting for age and sex. Increased myocardial native T1 value was associated with reduced LV strain after adjusting age, sex, and LVMI.

CONCLUSIONS

ESRD patients on peritoneal dialysis with preserved LVEF demonstrated higher myocardial mass, higher native T1 and T2 values, decreased LV strain, and increased RVGCS compared with healthy controls. Increased myocardial T1 and T2 were found in ESRD even when no systolic or diastolic dysfunction was detected by routine echocardiography.

KEY POINTS

• Even with preserved LVEF and no known cardiovascular diseases, ESRD patients on peritoneal dialysis demonstrated elevated myocardial T1 and T2 values and decreased left ventricular strain. • Subclinical changes in myocardial tissue composition may exist in ESRD patients on peritoneal dialysis even when no systolic or diastolic dysfunction was detected by routine echocardiography based on ejection fraction, left atrium size, and tissue Doppler. • Right ventricular free wall strain could be enhanced in response to subclinical LV systolic dysfunction in ESRD patients on peritoneal dialysis with preserved LVEF at an early stage.

Uraemic Cardiomyopathy: A Review of Current Literature

Uraemic Cardiomyopathy (UC) is recognised as an intricate and multifactorial disease which portends a significant burden in patients with End-Stage Renal Disease (ESRD). The cardiovascular morbidity and mortality associated with UC is significant and can be associated with the development of arrythmias, cardiac failure and sudden cardiac death (SCD). The pathophysiology of UC involves a complex interplay of traditional implicative factors such as haemodynamic overload and circulating uraemic toxins as well as our evolving understanding of the Chronic Kidney Disease-Mineral Bone Disease pathway. There is an instrumental role for multi-modality imaging in the diagnostic process; including transthoracic echocardiography and cardiac magnetic resonance imaging in identifying the hallmarks of left ventricular hypertrophy and myocardial fibrosis that characterise UC. The appropriate utilisation of the aforementioned diagnostics in the ESRD population may help guide therapeutic approaches, such as pharmacotherapy including beta-blockers and aldosterone-antagonists as well as haemodialysis and renal transplantation. Despite this, there remains limitations in effective therapeutic interventions for UC and ongoing research on a cellular level is vital in establishing further therapies.

Texture Analysis of Native T1 Images as a Novel Method for Noninvasive Assessment of Uremic Cardiomyopathy

BACKGROUND

Noncontrast cardiac T₁ times are increased in dialysis patients which might indicate fibrotic alterations in uremic cardiomyopathy.

PURPOSE

To explore the application of the texture analysis (TA) of T₁ images in the assessment of myocardial alterations in dialysis patients.

STUDY TYPE

Case-control study.

POPULATION

A total of 117 subjects, including 22 on hemodialysis, 44 on peritoneal dialysis, and 51 healthy controls.

FIELD STRENGTH

A 3 T, steady-state free precession (SSFP) sequence, modified Look-Locker imaging (MOLLI).

ASSESSMENT

Two independent, blinded researchers manually delineated endocardial and epicardial borders of the left ventricle (LV) on midventricular T₁ maps for TA.

STATISTICAL TESTS

Texture feature selection was performed, incorporating reproducibility verification, machine learning, and collinearity analysis. Multivariate linear regressions were performed to examine the independent associations between the selected texture features and left ventricular function in dialysis patients. Texture features' performance in discrimination was evaluated by sensitivity and specificity. Reproducibility was estimated by the intraclass correlation coefficient (ICC).

RESULTS

Dialysis patients had greater T₁ values than normal (P < 0.05). Five texture features were filtered out through feature selection, and four showed a statistically significant difference between dialysis patients and healthy controls. Among the four features, vertical run-length nonuniformity (VRLN) had the most remarkable difference among the control and dialysis groups (144 ± 40 vs. 257 ± 74, P < 0.05), which overlap was much smaller than Global T₁ times (1268 ± 38 vs. 1308 ± 46 msec, P < 0.05). The VRLN values were notably elevated (cutoff = 170) in dialysis patients, with a specificity of 97% and a sensitivity of 88%, compared with T₁ times (specificity = 76%, sensitivity = 60%). In dialysis patients, VRLN was significantly and independently associated with left ventricular ejection fraction (P < 0.05), global longitudinal strain (P < 0.05), radial strain (P < 0.05), and circumferential strain (P < 0.05); however, T₁ was not.

DATA CONCLUSION

The texture features obtained by TA of T₁ images and VRLN may be a better parameter for assessing myocardial alterations than T₁ times.

LEVEL OF EVIDENCE

4 TECHNICAL EFFICACY: Stage 3.

Cardiovascular Functional Reserve Before and After Kidney Transplant

Importance

Restitution of kidney function by transplant confers a survival benefit in patients with end-stage renal disease. Investigations of mechanisms involved in improved cardiovascular survival have relied heavily on static measures from echocardiography or cardiac magnetic resonance imaging and have provided conflicting results to date.

Objectives

To evaluate cardiovascular functional reserve in patients with end-stage renal disease before and after kidney transplant and to assess functional and morphologic alterations of structural-functional dynamics in this population.

Design, Setting, and Participants

This prospective, nonrandomized, single-center, 3-arm, controlled cohort study, the Cardiopulmonary Exercise Testing in Renal Failure and After Kidney Transplantation (CAPER) study, included patients with stage 5 chronic kidney disease (CKD) who underwent kidney transplant (KTR group), patients with stage 5 CKD who were wait-listed and had not undergone transplant (NTWC group), and patients with hypertension only (HTC group) seen at a single center from April 1, 2010, to January 1, 2013. Patients were followed up longitudinally for up to 1 year after kidney transplant. Clinical data collection was completed February 2014. Data analysis was performed from June 1, 2014, to March 5, 2015. Further analysis on baseline and prospective data was performed from June 1, 2017, to July 31, 2019.

Main Outcomes and Measures

Cardiovascular functional reserve was objectively quantified using state-of-the-art cardiopulmonary exercise testing in parallel with transthoracic echocardiography.

Results

Of the 253 study participants (mean [SD] age, 48.5 [12.7] years; 141 [55.7%] male), 81 were in the KTR group, 85 in the NTWC group, and 87 in the HTC group. At baseline, mean (SD) maximum oxygen consumption (V̇O2max) was significantly lower in the CKD groups (KTR, 20.7 [5.8] mL · min-1 · kg-1; NTWC, 18.9 [4.7] mL · min-1 · kg-1) compared with the HTC group (24.9 [7.1] mL · min-1 · kg-1) (P < .001). Mean (SD) cardiac left ventricular mass index was higher in patients with CKD (KTR group, 104.9 [36.1] g/m2; NTWC group, 113.8 [37.7] g/m2) compared with the HTC group (87.8 [16.9] g/m2), (P < .001). Mean (SD) left ventricular ejection fraction was significantly lower in the patients with CKD (KTR group, 60.1% [8.6%]; NTWC group, 61.4% [8.9%]) compared with the HTC group (66.1% [5.9%]) (P < .001). Kidney transplant was associated with a significant improvement in V̇O2max in the KTR group at 12 months (22.5 [6.3] mL · min-1 · kg-1; P < .001), but the value did not reach the V̇O2max in the HTC group (26.0 [7.1] mL · min-1 · kg-1) at 12 months. V̇O2max decreased in the NTWC group at 12 months compared with baseline (17.7 [4.1] mL · min-1 · kg-1, P < .001). Compared with the KTR group (63.2% [6.8%], P = .02) or the NTWC group (59.3% [7.6%], P = .003) at baseline, transplant was significantly associated with improved left ventricular ejection fraction at 12 months but not with left ventricular mass index.

Conclusions and Relevance

The findings suggest that kidney transplant is associated with improved cardiovascular functional reserve after 1 year. In addition, cardiopulmonary exercise testing was sensitive enough to detect a decline in cardiovascular functional reserve in wait-listed patients with CKD. Improved V̇O2max may in part be independent from structural alterations of the heart and depend more on ultrastructural changes after reversal of uremia.

Better peridialytic blood pressure control using carvedilol in end stage renal disease patients on twice weekly maintenance hemodialysis

BACKGROUND

While use of carvedilol in patients on hemodialysis is encouraged with its low dialyzability, evidence supporting its superiority over metoprolol in improving the blood pressure control during dialysis is lacking. This study was undertaken to study the blood pressure variations in the peridialytic period after conversion from metoprolol to carvedilol.

MATERIALS AND METHODS

In this this prospective, pre-post intervention study, patients on metoprolol were converted to carvedilol. Patients aged 18-65 years on biweekly dialysis with intradialytic rise in blood pressure {difference between pre- and post-dialysis systolic blood pressure > 10 mmHg with post-dialysis blood pressure of ≥ 130/80 mmHg} were recruited. The recorded blood pressure data post conversion to carvedilol was compared to the retrospective mean blood pressure recordings during metoprolol use.

RESULTS

Of the 48 subjects, the study mostly comprised young males (n-34, mean age- 37.06 ± 14.32 years). Both systolic and diastolic blood pressures at different time periods (pre-dialysis, intradialytic and post-dialysis) were significantly lower with carvedilol use than with metoprolol, p < 0.001. Mean pre-dialysis systolic blood pressures and diastolic blood pressures were 140.54 ± 7.68 and 84.42 ± 7.78 mmHg on carvedilol as compared to 148.12 ± 7.17 and 91.17 ± 6.97 mmHg on metoprolol (p < 0.001). Post-dialysis systolic blood pressures and diastolic blood pressures during Carvedilol regimen were better controlled at 147.42 ± 12.89 and 86.29 ± 7.31 mmHg, than 159.12 ± 8.18 and 97 ± 6.76 mmHg during metoprolol regimen (p < 0.001).

CONCLUSION

Our study has brought into focus the younger population at risk of peridialytic hypertension. Switch from metoprolol to carvedilol is an effective anti-hypertensive strategy in dialysis patients with poorly controlled peridialytic blood pressures. Carvedilol was well tolerated.

Combination Hydralazine and Isosorbide Dinitrate in Dialysis-Dependent ESRD (HIDE): A Randomized, Placebo-Controlled, Pilot Trial

Background

Combination therapy with isosorbide dinitrate (ISD) and hydralazine (HY) reduces heart failure mortality. The safety and tolerability in individuals requiring maintenance hemodialysis (HD) is unknown.

Methods

Single-center, randomized, placebo-controlled, double-blind pilot trial to explore safety and tolerability of ISD/HY in maintenance HD. Participants were randomized to placebo or combination ISD/HY. Dose was escalated over 3 weeks from ISD 10 mg/HY 10 mg to ISD 40 mg/HY 75 mg three times per day with the maximum tolerated dose maintained for the subsequent 21 weeks. Primary endpoints included adverse events, adverse events precluding further treatment with study medication, serious hypotension (i.e., requiring hospitalization or emergency room visit), and recurrent intra-dialytic hypotension. Efficacy signals included change in mitral annular E' velocity by tissue Doppler echocardiography and change in left ventricular coronary flow reserve on positron emission tomography.

Results

A total of 17 individuals were randomized to ISD/HY (N=7) or placebo (N=10). All participants assigned to ISD/HY completed dose escalation to 40/75 mg, but dose reductions were required in two participants. No participants discontinued therapy. There were no serious hypotension events. Recurrent intradialytic hypotension was less frequent with ISD/HY (0.47 events/patient-year) than placebo (1.83 events/patient-year, P=0.04). In contrast, nausea (ISD/HY, 1.90 events/patient-year; placebo, 0.50 events/patient-year, P=0.03) was significantly more frequent, and headache and diarrhea were numerically but not significantly more frequent with ISD/HY. Adverse events were more frequent with ISD/HY (11.4 events/patient-year) than placebo (6.31 events/patient-year). We did not detect between-group differences in the change in E' (P=0.34); ISD/HY showed a mean increase of 0.6 cm/s (SD 1.1), and placebo showed a mean decrease of 0.04 cm/s (SD 0.9). Changes in coronary flow reserve were minimal, -0.3 (0.2) with ISD/HY and -0.03 (0.5) in the placebo group, P=0.19.

Conclusions

ISD/HY appears to be well tolerated in patients being treated with maintenance HD, but headache and gastrointestinal side effects occur more frequently with ISD/HY compared with placebo.

Heart failure in chronic kidney disease: the emerging role of myocardial fibrosis

Heart failure (HF) is one of the main causes of morbidity and mortality in patients with chronic kidney disease (CKD). Decreased glomerular filtration rate is associated with diffuse deposition of fibrotic tissue in the myocardial interstitium [i.e. myocardial interstitial fibrosis (MIF)] and loss of cardiac function. MIF results from cardiac fibroblast-mediated alterations in the turnover of fibrillary collagen that lead to the excessive synthesis and deposition of collagen fibres. The accumulation of stiff fibrotic tissue alters the mechanical properties of the myocardium, thus contributing to the development of HF. Accumulating evidence suggests that several mechanisms are operative along the different stages of CKD that may converge to alter fibroblasts and collagen turnover in the heart. Therefore, focusing on MIF might enable the identification of fibrosis-related biomarkers and targets that could potentially lead to a new strategy for the prevention and treatment of HF in patients with CKD. This article summarizes current knowledge on the mechanisms and detrimental consequences of MIF in CKD and discusses the validity and usefulness of available biomarkers to recognize the clinical-pathological variability of MIF and track its clinical evolution in CKD patients. Finally, the currently available and potential future therapeutic strategies aimed at personalizing prevention and reversal of MIF in CKD patients, especially those with HF, will be also discussed.

Chronic kidney disease, heart failure and neprilysin inhibition

Patients with chronic kidney disease are at increased risk of cardiovascular disease and this often manifests clinically like heart failure. Conversely, patients with heart failure frequently have reduced kidney function. The links between the kidneys and cardiovascular system are being elucidated, with blood pressure being a key risk factor. Patients with heart failure have benefitted from many trials which have now established a strong evidence based on which to base management. However, patients with advanced kidney disease have often been excluded from these trials. Nevertheless, there is little evidence that the benefits of such treatments are modified by the presence or absence of kidney disease, but more direct evidence among patients with advanced kidney disease is required. Neprilysin inhibition is the most recent treatment to be shown to improve outcomes among patients with heart failure. The UK HARP-III trial assessed whether neprilysin inhibition improved kidney function in the short- to medium-term and its effects on cardiovascular biomarkers. Although no effect (compared to irbesartan control) was found on kidney function, allocation to neprilysin inhibition (sacubitril/valsartan) did reduce cardiac biomarkers more than irbesartan, suggesting that this treatment might improve cardiovascular outcomes in this population. Larger clinical outcomes trials are needed to test this hypothesis.

Quantification of extracellular volume fraction by cardiac computed tomography for noninvasive assessment of myocardial fibrosis in hemodialysis patients

Extent of myocardial fibrosis in hemodialysis patients has been associated with poor prognosis. Myocardial extracellular volume (ECV) quantification using contrast enhanced cardiac computed tomography (CT) is a novel method to determine extent of myocardial fibrosis. Cardiac CT-based myocardial ECV in hemodialysis patients with those of propensity-matched non-hemodialysis control subjects were compared. Twenty hemodialysis patients (mean age, 67.4 ± 9.6 years; 80% male) and 20 propensity-matched non-hemodialysis controls (mean age, 66.3 ± 9.1 years; 85% male) who underwent comprehensive cardiac CT consisted of calcium scoring, coronary CT angiography, stress perfusion CT and delayed enhancement CT were evaluated. Myocardial ECV was significantly greater in the hemodialysis group than in the control group (33.8 ± 4.7% versus 26.6 ± 2.9%; P < 0.0001). In the hemodialysis group, modest correlation was evident between myocardial ECV and left atrial volume index (r = 0.54; P = 0.01), while there was no correlation between myocardial ECV and other cardiac parameters including left ventricular mass index and severity of myocardial ischemia. Cardiac CT-based myocardial ECV may offer a potential imaging biomarker for myocardial fibrosis in HD patients.

Cardiovascular Functional Changes in Chronic Kidney Disease: Integrative Physiology, Pathophysiology and Applications of Cardiopulmonary Exercise Testing

The development of cardiovascular disease during renal impairment involves striking multi-tiered, multi-dimensional complex alterations encompassing the entire oxygen transport system. Complex interactions between target organ systems involving alterations of the heart, vascular, musculoskeletal and respiratory systems occur in Chronic Kidney Disease (CKD) and collectively contribute to impairment of cardiovascular function. These systemic changes have challenged our diagnostic and therapeutic efforts, particularly given that imaging cardiac structure at rest, rather than ascertainment under the stress of exercise, may not accurately reflect the risk of premature death in CKD. The multi-systemic nature of cardiovascular disease in CKD patients provides strong rationale for an integrated approach to the assessment of cardiovascular alterations in this population. State-of-the-art cardiopulmonary exercise testing (CPET) is a powerful, dynamic technology that enables the global assessment of cardiovascular functional alterations and reflects the integrative exercise response and complex machinery that form the oxygen transport system. CPET provides a wealth of data from a single assessment with mechanistic, physiological and prognostic utility. It is an underutilized technology in the care of patients with kidney disease with the potential to help advance the field of cardio-nephrology. This article reviews the integrative physiology and pathophysiology of cardio-renal impairment, critical new insights derived from CPET technology, and contemporary evidence for potential applications of CPET technology in patients with kidney disease.

Histological features of endomyocardial biopsies in patients undergoing hemodialysis: Comparison with dilated cardiomyopathy and hypertensive heart disease

BACKGROUND

Heart failure is a frequently occurring complication in patients on maintenance hemodialysis (HD). However, the histological features of right ventricular endomyocardial biopsy (RVEMB) samples remain unclear.

METHODS

The clinical characteristics and histological findings of consecutive patients undergoing HD with available RVEMB samples (HD group; n=28) were retrospectively compared with those of patients with dilated cardiomyopathy (n=56) and hypertensive heart disease (n=15).

RESULTS

The mean myocyte diameter was significantly larger in the HD group than in the other groups (P<.001), whereas the mean percent area of fibrosis did not differ among the three groups. Immunohistochemical analysis revealed that the capillary density was significantly lower in the HD group compared with the other groups (P<.001), and it was positively associated with left ventricular ejection fraction (P=.014). The number of CD68-positive macrophages, which was significantly higher in the HD group compared with the other two groups (P<.001), was associated with cardiovascular mortality (P=.020; log-rank test).

CONCLUSIONS

Myocyte hypertrophy, macrophage infiltration, and reduced capillary density were characteristic histological features of the RVEMB samples in patients undergoing HD, which may be related to the pathogenesis of cardiac dysfunction.

The reliability and feasibility of non-contrast adenosine stress cardiovascular magnetic resonance T1 mapping in patients on haemodialysis

BACKGROUND

Identifying coronary artery disease (CAD) in patients with end-stage renal disease (ESRD) is challenging. Adenosine stress native T1 mapping with cardiovascular magnetic resonance (CMR) may accurately detect obstructive CAD and microvascular dysfunction in the general population. This study assessed the feasibility and reliability of adenosine stress native T1 mapping in patients on haemodialysis.

METHODS

The feasibility of undertaking rest and adenosine stress native T1 mapping using the single-shot Modified Look-Locker inversion recovery (MOLLI) sequence was assessed in 58 patients on maintenance haemodialysis using 3 T CMR. Ten patients underwent repeat stress CMR within 2 weeks for assessment of test-retest reliability of native T1, stress T1 and delta T1 (ΔT1). Interrater and intrarater agreement were assessed in 10 patients. Exploratory analyses were undertaken to assess associations between clinical variables and native T1 values in 51 patients on haemodialysis.

RESULTS

Mean age of participants was 55 ± 15 years, 46 (79%) were male, and median dialysis vintage was 21 (8; 48) months. All patients completed the scan without complications. Mean native T1 rest, stress and ΔT1 were 1261 ± 57 ms, 1297 ± 50 ms and 2.9 ± 2.5%, respectively. Interrater and intrarater agreement of rest T1, stress T1 and ΔT1 were excellent, with intraclass correlation coefficients (ICC) > 0.9 for all. Test-retest reliability of rest and stress native T1 were excellent or good (CoV 1.2 and 1.5%; ICC, 0.79 and 0.69, respectively). Test-retest reliability of ΔT1 was moderate to poor (CoV 27.4%, ICC 0.55). On multivariate analysis, CAD, diabetes mellitus and resting native T1 time were independent determinants of ΔT1 (β = - 0.275, p = 0.019; β = - 0.297, p = 0.013; β = - 0.455; p < 0.001, respectively).

CONCLUSIONS

Rest and adenosine stress native T1 mapping is feasible and well-tolerated amongst patients with ESRD on haemodialysis. Although rater agreement of the technique is excellent, test-retest reliability of ΔT1 is moderate to poor. Prospective studies should evaluate the relationship between this technique and established methods of CAD assessment and association with outcomes.