Association Between Diffuse Myocardial Fibrosis by Cardiac Magnetic Resonance Contrast-Enhanced T 1 Mapping and Subclinical Myocardial Dysfunction in Diabetic Patients

Lipotoxicity as a therapeutic target in the type 2 diabetic heart

Cardiac lipotoxicity, characterized by excessive lipid accumulation in the cardiac tissue, is a critical contributor to the pathogenesis of diabetic heart. Recent research has highlighted the key mechanisms underlying lipotoxicity, including mitochondrial dysfunction, endoplasmic reticulum stress, inflammation, and cell apoptosis, which ultimately impair the cardiac function. Various therapeutic interventions have been developed to target these pathways, mitigate lipotoxicity, and improve cardiovascular outcomes in diabetic patients. Given the global escalation in the prevalence of diabetes and the urgent demand for effective therapeutic approaches, this review focuses on how targeting cardiac lipotoxicity may be a promising avenue for treating diabetes.

Fibroblast-specific TGF-β signaling mediates cardiac dysfunction, fibrosis, and hypertrophy in obese diabetic mice

AIMS

Transforming growth factor (TGF)-β is up-regulated in the diabetic myocardium and may mediate fibroblast activation. We aimed at examining the role of TGF-β-induced fibroblast activation in the pathogenesis of diabetic cardiomyopathy.

METHODS AND RESULTS

We generated lean and obese db/db mice with fibroblast-specific loss of TbR2, the Type 2 receptor-mediating signaling through all three TGF-β isoforms, and mice with fibroblast-specific Smad3 disruption. Systolic and diastolic function, myocardial fibrosis, and hypertrophy were assessed. Transcriptomic studies and in vitro experiments were used to dissect mechanisms of fibroblast activation. Fibroblast-specific TbR2 loss attenuated systolic and diastolic dysfunction in db/db mice. The protective effects of fibroblast TbR2 loss in db/db mice were associated with attenuated fibrosis and reduced cardiomyocyte hypertrophy, suggesting that in addition to their role in fibrous tissue deposition, TGF-β-stimulated fibroblasts may also exert paracrine actions on cardiomyocytes. Fibroblast-specific Smad3 loss phenocopied the protective effects of fibroblast TbR2 loss in db/db mice. Db/db fibroblasts had increased expression of genes associated with oxidative response (such as Fmo2, encoding flavin-containing monooxygenase 2), matricellular genes (such as Thbs4 and Fbln2), and Lox (encoding lysyl oxidase). Ingenuity pathway analysis (IPA) predicted that neurohumoral mediators, cytokines, and growth factors (such as AGT, TGFB1, and TNF) may serve as important upstream regulators of the transcriptomic profile of diabetic mouse fibroblasts. IPA of scRNA-seq data identified TGFB1, p53, MYC, PDGF-BB, EGFR, and WNT3A/CTNNB1 as important upstream regulators underlying fibroblast activation in db/db hearts. Comparison of the transcriptome of fibroblasts from db/db mice with fibroblast-specific Smad3 loss and db/db Smad3 fl/fl controls identified Thbs4 [encoding thrombospondin-4 (TSP-4), a marker of activated fibroblasts] as a candidate diabetes-induced fibrogenic mediator. However, in vitro experiments showed no significant activating effects of matricellular or intracellular TSP-4 on cardiac fibroblasts.

CONCLUSION

Fibroblast-specific TGF-β/Smad3 signaling mediates ventricular fibrosis, hypertrophy, and dysfunction in Type 2 diabetes.

Diabetic cardiomyopathy: pathophysiology, imaging assessment and therapeutical strategies

Diabetes mellitus (DM) is one of the most prevalent cardiovascular risk factors in the general population, being associated with high morbidity and socioeconomic burden. Diabetic cardiomyopathy (DCM) is a non-negligible complication of DM, whose pathophysiological fundaments are the altered cardiac metabolism, the hyperglycemia-triggered formation of advanced glycation end-products (AGEs) and the inflammatory milieu which are typical in diabetic patients. These metabolic abnormalities lead to cardiomyocytes apoptosis, interstitial fibrosis and mechanical cardiac dysfunction, which can be identified with non-invasive imaging techniques, like echocardiography and cardiac magnetic resonance. This review aims to: 1) describe the major imaging features of DCM; 2) highlight how early identification of DCM-related anatomical and functional remodeling might allow patients' therapy optimization and prognosis improvement.

Type 2 diabetes mellitus and cardiovascular health: Evidence of causal relationships in a European ancestry population

AIMS

Type 2 diabetes mellitus (T2DM) is associated with increased cardiovascular disease (CVD) risk, but whether T2DM directly causes adverse cardiac remodelling is uncertain. We performed a comprehensive Mendelian randomization (MR) analysis to investigate the causal relevance of T2DM to CVD outcomes and cardiac structure/function.

METHODS AND RESULTS

Bidirectional two-sample MR was conducted using summary-level data from European-ancestry genome-wide association studies. The T2DM GWAS data included 80 154 cases and 853 816 controls from the DIAGRAM consortium. Outcomes included coronary artery disease (CAD), myocardial infarction (MI), stroke, heart failure, atrial fibrillation, and various quantitative cardiac imaging traits assessed by magnetic resonance imaging. MR analysis revealed causal associations between genetic predisposition to T2DM and increased risk of CAD (odds ratio [OR] 1.104, 95% confidence interval [CI] 1.078-1.130, P = 2.59e-16), MI (OR 1.129, 95% CI 1.094-1.166, P = 6.02e-14) and stroke (OR 1.086, 95% CI 1.064-1.109, P = 1.02e-14). These associations were validated in the FinnGen cohort (CAD: OR 1.117, 95% CI 1.075-1.158, P = 1.56e-9; MI: OR 1.132, 95% CI 1.083-1.184, P = 4.27e-8; stroke: OR 1.138, 95% CI 1.107-1.170, P = 3.52e-20). Multivariable MR show consistent findings (CAD: OR 1.063, 95% CI 1.031-1.097, P = 1.11e-4; MI: OR 1.088, 95% CI 1.042-1.135, P = 1.12e-4; stroke: OR 1.066, 95% CI 1.032-1.101, P = 1.18e-4) after adjusting for cardiometabolic traits. T2DM was causally associated with higher left ventricular mass index (β = 0.473, 95% CI 0.193 to 0.752, P = 0.001), lower indexed right atrial minimum (β = -0.048, 95% CI -0.073 to -0.022, P = 2.1e-5), and maximum (β = -0.042, 95% CI -0.065 to -0.019, P = 4.12e-5) areas. The effects on right atrial size remained significant after adjusting for risk factors (minimum area: β = -0.041, 95% CI -0.072 to -0.010, P = 0.009; maximum area: β = -0.039, 95% CI -0.069 to -0.008, P = 0.012). Both apolipoprotein A1 and SBP are important mediators in the causal relationship between T2DM and left ventricular mass index. No reverse causal associations were identified.

CONCLUSIONS

Our MR study demonstrates that genetic liability to T2DM plays causal roles in CAD, MI, stroke, and cardiac structure changes including left ventricular hypertrophy and reduced right atrial dimensions. These findings provide genetic evidence supporting glycaemic control in T2DM to mitigate cardiovascular complications and adverse cardiac remodelling.

Assessment of myocardial microvascular dysfunction in patients with different stages of diabetes mellitus: An adenosine stress perfusion cardiac magnetic resonance study

PURPOSE

To examine myocardial perfusion and T1 mapping indicesin individuals with type 2 diabetes mellitus (T2DM) at various stages of glycemic control and whether uncontrolled glycemic levels would worsen myocardial microvascular function.

METHOD

Cardiac magnetic resonance examinations were performed on 114 T2DM patients without obstructive coronary artery disease and 55 matched controls. Participants were further divided into four subgroups: Q1 (control); Q2 (prediabetes); Q3 (controlled T2DM) and Q4 (uncontrolled T2DM). The correlation between glycosylated hemoglobin (HbA1c) levels and myocardial perfusion parameters was evaluated.

RESULTS

Global myocardial perfusion reserve index (MPRI) was significantly reduced in the Q3 and Q4 subgroups compared to the Q1 or Q2 subgroup (all P<0.001). Compared with the Q1 subgroup, global stress T1 reactivity (stress ΔT1) was significantly reduced in the Q3 and Q4 subgroups (P=0.004 and < 0.001, respectively), but elevated in the Q2 subgroup (P=0.018). Global extracellular volume (ECV) was considerably higher in the Q2 subgroup and gradually rose in the Q3 and Q4 subgroups compared to the Q1 subgroup (P=0.011, 0.001, and 0.007, respectively). HbA1c levels correlated negatively with global MPRI and stress ΔT1, but positively with global ECV (β = -1.993, P<0.001; β = -0.180, P<0.001; and β = 0.127, P<0.001, respectively).

CONCLUSIONS

Global stress ΔT1 reduced in T2DM patients but rose in prediabetes patients. Compared to MPRI, the ECV parameter can indicate diabetes-induced coronary microvascular dysfunction earlier and persists throughout the disorder. Myocardial perfusion and T1 mapping at stress can be used to detect early signs of microvascular dysfunction and subclinical risk factors in patients with T2DM.

Unveiling myocardial microstructure shifts: exploring the impact of diabetes in stable CAD patients through CMR T1 mapping

BACKGROUND

This study investigates myocardial structural changes in stable coronary artery disease (CAD) patients with type 2 diabetes (T2D) using cardiac magnetic resonance (CMR) strain and T1 mapping.

METHODS

A total of 155 stable CAD patients underwent CMR examination, including left ventricular (LV) morphology and function assessment, late gadolinium enhancement (LGE), and feature tracking (CMR-FT) for LV global longitudinal, circumferential, and radial strain. T1 mapping with extracellular volume (ECV) evaluation was also performed.

RESULTS

Among the enrolled patients, 67 had T2D. Diabetic patients exhibited impaired LV strain and higher ECV compared to non-diabetics. Multivariate analysis identified T2D as an independent predictor of increased ECV and decreased strain.

CONCLUSIONS

CMR-based strain and T1 mapping highlighted impaired myocardial contractility, elevated ECV, and potential interstitial fibrosis in diabetic patients with stable CAD. This suggests a significant impact of diabetes on myocardial health beyond CAD, emphasizing the importance of a comprehensive assessment in these individuals.

TRIAL REGISTRATION

http://www.controlled-trials.com/ISRCTN09454308.

Cardiovascular Imaging for Coronary Artery Disease in Patients with Diabetes Mellitus

In patients with diabetes mellitus, accelerated progression of atherosclerosis can lead to worse clinical outcomes. Determining the best diagnostic strategy to identify patients with increased cardiovascular risk is challenging. Current guidelines recommend using both functional imaging and CT angiography to detect myocardial ischemia and coronary artery disease based on pre-test probability. Functional imaging is suggested for patients with a higher clinical likelihood due to its higher rule-in diagnostic capacity. On the other hand, CT angiography is preferred for patients with lower pre-test probability because of its excellent negative predictive value. The optimal management strategy for asymptomatic diabetic patients remains unclear. In asymptomatic diabetic patients, previous randomized trials have not shown benefits from diagnostic testing over standard care. However, these trials were methodologically inconsistent and lacked clear stratification of cardiovascular risk. In terms of invasive evaluation, a combined invasive functional and anatomic imaging approach for angiographically intermediate coronary stenosis appears to be the best, most effective decision pathway for managing diabetic patients.

Roles of cMyBP-C phosphorylation on cardiac contractile dysfunction in db/db mice

Type 2 diabetes mellitus (T2DM) is a metabolic disease and comorbidity associated with several conditions, including cardiac dysfunction leading to heart failure with preserved ejection fraction (HFpEF), in turn resulting in T2DM-induced cardiomyopathy (T2DM-CM). However, the molecular mechanisms underlying the development of T2DM-CM are poorly understood. It is hypothesized that molecular alterations in myopathic genes induced by diabetes promote the development of HFpEF, whereas cardiac myosin inhibitors can rescue the resultant T2DM-mediated cardiomyopathy. To test this hypothesis, a Leptin receptor-deficient db/db homozygous (Lepr db/db) mouse model was used to define the pathogenesis of T2DM-CM. Echocardiographic studies at 4 and 6 months revealed that Lepr db/db hearts started developing cardiac dysfunction by four months, and left ventricular hypertrophy with diastolic dysfunction was evident at 6 months. RNA-seq data analysis, followed by functional enrichment, revealed the differential regulation of genes related to cardiac dysfunction in Lepr db/db heart tissues. Strikingly, the level of cardiac myosin binding protein-C phosphorylation was significantly increased in Lepr db/db mouse hearts. Finally, using isolated skinned papillary muscles and freshly isolated cardiomyocytes, CAMZYOS ® (mavacamten, MYK-461), a prescription heart medicine used for symptomatic obstructive hypertrophic cardiomyopathy treatment, was tested for its ability to rescue T2DM-CM. Compared with controls, MYK-461 significantly reduced force generation in papillary muscle fibers and cardiomyocyte contractility in the db/db group. This line of evidence shows that 1) T2DM-CM is associated with hyperphosphorylation of cardiac myosin binding protein-C and 2) MYK-461 significantly lessened disease progression in vitro, suggesting its promise as a treatment for HFpEF.

Redefining Diabetic Cardiomyopathy: Perturbations in Substrate Metabolism at the Heart of Its Pathology

Cardiovascular disease represents the leading cause of death in people with diabetes, most notably from macrovascular diseases such as myocardial infarction or heart failure. Diabetes also increases the risk of a specific form of cardiomyopathy, referred to as diabetic cardiomyopathy (DbCM), originally defined as ventricular dysfunction in the absence of underlying coronary artery disease and/or hypertension. Herein, we provide an overview on the key mediators of DbCM, with an emphasis on the role for perturbations in cardiac substrate metabolism. We discuss key mechanisms regulating metabolic dysfunction in DbCM, with additional focus on the role of metabolites as signaling molecules within the diabetic heart. Furthermore, we discuss the preclinical approaches to target these perturbations to alleviate DbCM. With several advancements in our understanding, we propose the following as a new definition for, or approach to classify, DbCM: "diastolic dysfunction in the presence of altered myocardial metabolism in a person with diabetes but absence of other known causes of cardiomyopathy and/or hypertension." However, we recognize that no definition can fully explain the complexity of why some individuals with DbCM exhibit diastolic dysfunction, whereas others develop systolic dysfunction. Due to DbCM sharing pathological features with heart failure with preserved ejection fraction (HFpEF), the latter of which is more prevalent in the population with diabetes, it is imperative to determine whether effective management of DbCM decreases HFpEF prevalence.

ARTICLE HIGHLIGHTS

The role of diabetic foot treatment in improving left ventricular function: Insights from global longitudinal strain echocardiography

We decided to evaluate the effect of treatment of diabetic foot ulcers in improving heart function by strain echocardiography than conventional transthoracic echocardiography. This prospective cross-sectional study included patients with diabetic foot ulcer (DFU). Conventional and two-dimensional strain echocardiography performed before and after three months diabetic foot treatment. Then, we compared the echocardiographic parameters including left ventricular ejection fraction (LV-EF), left ventricular global longitudinal strain (LV-GLS). Multivariate and univariate logistic regression analysis were performed to find which variable was mainly associated with LV-GLS changes. 62 patients with DFU were conducted. After echocardiography, all patients underwent surgical or non-surgical treatments. Three months after the treatment, LV-EF was not significantly different with its' primary values (P = 0.250), but LV-GLS became significantly different (P<0.05). In the multivariate logistic regression analysis, with the increase in the grade of ulcer, LV-GLS improved by 6.3 times. Not only the treatment of DFU helps to control adverse outcomes like infection, limb loss and morbidity but also it enhances cardiac function. Of note, strain echocardiography found to be a better indicator of myocardial dysfunction than LV-EF. These findings make a strong reason for the routine assessment of cardiac function in patients with DFU.

Inhibition of miR-543 alleviates cardiac fibroblast-to-myofibroblast transformation and collagen expression in insulin resistance via targeting PTEN

BACKGROUND

Myocardial interstitial fibrosis is an important manifestation of diabetic heart disease, and insulin resistance is one of the mechanisms of myocardial interstitial fibrosis. Some studies have found that miR-543 is associated with insulin resistance, but whether it plays a role in diabetic myocardial interstitial fibrosis remains unclear. This study aimed to investigate the role of miR-543 in diabetic myocardial interstitial fibrosis.

METHODS

The combination of high glucose and high insulin was used to establish an insulin-resistant myocardial fibroblast model. The expression levels of miR-543, α-SMA, collagen Ⅰ, collagen Ⅲ and PTEN were detected. Cell proliferation and migration were detected. Luciferase reporter gene assay was used to verify the targeting relationship between miR-543 and PTEN.

RESULTS

The expression of miR-543 was up-regulated in myocardial fibroblasts with insulin resistance, which was consistent with the results of bioinformatics analysis. The proliferation and migration levels of myocardial fibroblasts in insulin-resistant states were increased, and the expression levels of α-SMA, collagen Ⅰ and collagen Ⅲ were also increased. Inhibition of miR-543 expression could reverse the above changes. Target gene prediction and dual luciferase reporter assay demonstrated that miR-543 could bind to the 3'UTR region of PTEN. Moreover, the effect of miR-543 on insulin-resistant myocardial fibroblasts is mediated by targeting PTEN.

CONCLUSIONS

Inhibition of miR-543 can reduce myocardial fibroblast-myofibroblast transformation and collagen expression in insulin-resistant states by targeting PTEN.

Chronic troponin elevation assessed by myocardial T1 mapping in patients with stable coronary artery disease

BACKGROUND

Cardiac troponin detected with sensitive assays can be chronically elevated, in the absence of unstable coronary syndromes. In patients with chronic coronary artery disease, clinically silent ischemic episodes may cause chronic troponin release. T1 mapping is a cardiovascular magnetic resonance technique useful in quantitative cardiac tissue characterization. We selected patients with anatomically and functionally normal hearts to investigate associations between chronic troponin release and myocardial tissue characteristics assessed by T1 mapping.

METHODS

We investigated the relationship between cardiac troponin I concentrations and cardiovascular magnetic resonance T1 mapping parameters in patients with stable coronary artery disease enrolled in MASS V study before elective revascularization. Participants had no previous myocardial infarction, negative late gadolinium enhancement, normal left ventricular function, chamber dimensions and wall thickness.

RESULTS

A total of 56 patients were analyzed in troponin tertiles: nativeT1 and extracellular volume (ECV) values (expressed as means ± standard deviations) increased across tertiles: nativeT1 (1006 ± 27 ms vs 1016 ± 27 ms vs 1034 ± 37 ms, ptrend = 0.006) and ECV (22 ± 3% vs 23 ± 1.9% vs 25 ± 3%, ptrend = 0.007). Cardiac troponin I concentrations correlated with native T1(R = 0.33, P = .012) and ECV (R = 0.3, P = .025), and were independently associated with nativeT1 (P = .049) and ventricular mass index (P = .041) in multivariable analysis.

CONCLUSION

In patients with chronic coronary artery disease and structurally normal hearts, troponin I concentrations correlated with T1 mapping parameters, suggesting that diffuse edema or fibrosis scattered in normal myocardium might be associated with chronic troponin release.

Subclinical left ventricular systolic dysfunction and incident stroke in the elderly: long-term findings from Cardiovascular Abnormalities and Brain Lesions

AIMS

Heart disease is associated with an increased risk for ischaemic stroke. However, the predictive value of reduced left ventricular ejection fraction (LVEF) for stroke is controversial and only observed in patients with severe reduction. LV global longitudinal strain (LV GLS) can detect subclinical LV systolic impairment when LVEF is normal. We investigated the prognostic role of LV GLS for incident stroke in a predominantly elderly cohort.

METHODS AND RESULTS

Two-dimensional echocardiography with speckle tracking was performed in the Cardiac Abnormalities and Brain Lesions (CABL) study. Among 708 stroke-free participants (mean age 71.4 ± 9.4 years, 60.9% women), abnormal LV GLS (>-14.7%: 95% percentile of the subgroup without risk factors) was detected in 133 (18.8%). During a mean follow-up of 10.8 ± 3.9 years, 47 participants (6.6%) experienced an ischaemic stroke (26 cardioembolic or cryptogenic, 21 other subtypes). The cumulative incidence of ischaemic stroke was significantly higher in participants with abnormal LV GLS than with normal LV GLS (P < 0.001). In multivariate stepwise logistic regression analysis, abnormal LV GLS was associated with ischaemic stroke independently of cardiovascular risk factors including LVEF, LV mass, left atrial volume, subclinical cerebrovascular disease at baseline, and incident atrial fibrillation [hazard ratio (HR): 2.69, 95% confidence interval (CI): 1.47-4.92; P = 0.001]. Abnormal LV GLS independently predicted cardioembolic or cryptogenic stroke (adjusted HR: 3.57, 95% CI: 1.51-8.43; P = 0.004) but not other subtypes.

CONCLUSION

LV GLS was a strong independent predictor of ischaemic stroke in a predominantly elderly stroke-free cohort. Our findings provide insights into the brain-heart interaction and may help improve stroke primary prevention strategies.

Quantitative MRI in cardiometabolic disease: From conventional cardiac and liver tissue mapping techniques to multi-parametric approaches

Cardiometabolic disease refers to the spectrum of chronic conditions that include diabetes, hypertension, atheromatosis, non-alcoholic fatty liver disease, and their long-term impact on cardiovascular health. Histological studies have confirmed several modifications at the tissue level in cardiometabolic disease. Recently, quantitative MR methods have enabled non-invasive myocardial and liver tissue characterization. MR relaxation mapping techniques such as T₁, T_1ρ, T₂ and T₂* provide a pixel-by-pixel representation of the corresponding tissue specific relaxation times, which have been shown to correlate with fibrosis, altered tissue perfusion, oedema and iron levels. Proton density fat fraction mapping approaches allow measurement of lipid tissue in the organ of interest. Several studies have demonstrated their utility as early diagnostic biomarkers and their potential to bear prognostic implications. Conventionally, the quantification of these parameters by MRI relies on the acquisition of sequential scans, encoding and mapping only one parameter per scan. However, this methodology is time inefficient and suffers from the confounding effects of the relaxation parameters in each single map, limiting wider clinical and research applications. To address these limitations, several novel approaches have been proposed that encode multiple tissue parameters simultaneously, providing co-registered multiparametric information of the tissues of interest. This review aims to describe the multi-faceted myocardial and hepatic tissue alterations in cardiometabolic disease and to motivate the application of relaxometry and proton-density cardiac and liver tissue mapping techniques. Current approaches in myocardial and liver tissue characterization as well as latest technical developments in multiparametric quantitative MRI are included. Limitations and challenges of these novel approaches, and recommendations to facilitate clinical validation are also discussed.

Using T1 mapping indices to evaluate muscle function and predict conservative treatment outcomes in diabetic patients with peripheral arterial disease

OBJECTIVES

To investigate interstitial muscle fibrosis via T1 mapping indices and its relationships with muscle function and conservative treatment outcomes.

METHODS

A total of 49 DM patients with PAD were prospectively recruited from 2016 to 2017. All PAD patients underwent pre-treatment MRI with conservative treatment via a rehabilitation program and antiplatelet therapy. The need to require percutaneous transluminal angioplasty intervention was recorded as intolerance to conservative treatment outcomes. We quantified calf interstitial muscle fibrosis using T1 mapping indices (native T1, post-contrast T1, and the extracellular volume fraction [ECV]). Muscle function was evaluated using a 6-min walking test (6MWT) and a 3-min stepping test (3MST). PAD patients were divided into two groups according to their tolerance or intolerance of the conservative treatment. Pearson's correlation, reproducibility, and multivariable Cox hazard analyses were performed with p < 0.05 indicating statistical significance.

RESULTS

Among the T1 mapping indices in the posterior compartment of the calf in PAD patients, the native T1 value was significantly correlated with 6MWT (r =  -0.422, p = 0.010) and 3MST (r =  -0.427, p = 0.009). All T1 mapping indices showed excellent intra-observer and inter-observer correlations. ECV was an independent predictor of conservative treatment intolerance (average ECV, hazard ratio: 1.045, 95% confidence interval: 1.011-1.079, p = 0.009).

CONCLUSIONS

T1 mapping measurements are reproducible with excellent intra-observer and inter-observer correlations. T1 mapping indices may be predictive of treatment and functional outcomes and carry promise in patient evaluation.

TRIAL REGISTRATION

Clinical Trials Identifier: NCT02850432 .

KEY POINTS

• T1 mapping measurements of the calf muscles are reproducible with excellent intra-observer and inter-observer correlations (0.98 and 0.95 for anterior and posterior compartment muscle extracellular volume matrix [ECV] measurements, respectively). • ECV is shown to independently predict conservative treatment intolerance. • T1 mapping indices may be predictive of treatment and functional outcomes and carry promise in patient evaluation.

Impact of body mass index and diabetes on myocardial fat content, interstitial fibrosis and function

PURPOSE

We hypothesize that both increased myocardial steatosis and interstitial fibrosis contributes to subclinical myocardial dysfunction in patients with increased body mass index and diabetes mellitus.

BACKGROUND

Increased body weight and diabetes mellitus are both individually associated with a higher incidence of heart failure with preserved ejection fraction. However, it is unclear how increased myocardial steatosis and interstitial fibrosis interact to influence myocardial composition and function.

METHODS

A total of 100 subjects (27 healthy lean volunteers, 21 healthy but overweight volunteers, and 52 asymptomatic overweight patients with diabetes) were prospectively recruited to measure left ventricular (LV) myocardial steatosis (LV-myoFat) and interstitial fibrosis (by extracellular volume [ECV]) using magnetic resonance imaging, and then used to determine their combined impact on LV global longitudinal strain (GLS) analysis by 2-dimensional (2D) speckle tracking echocardiography on the same day.

RESULTS

On multivariable analysis, both increased body mass index and diabetes were independently associated with increased LV-myoFat. In turn, increased LV-myoFat was independently associated with increased LV ECV. Both increased LV-myoFat and LV ECV were independently associated with impaired 2D LV GLS.

CONCLUSION

Patients with increased body weight and patients with diabetes display excessive myocardial steatosis, which is related to a greater burden of myocardial interstitial fibrosis. LV myocardial contractile function was determined by both the extent of myocardial steatosis and interstitial fibrosis, and was independent of increasing age. Further study is warranted to determine how weight loss and improved diabetes management can improve myocardial composition and function.

T1 values and extracellular volume fraction in asymptomatic subjects: variations in left ventricular segments and correlation with cardiovascular risk factors

To evaluate variations in pre-contrast (preT1) and post-contrast (postT1) myocardial T1 values and extracellular volume fraction (ECV) according to left ventricular (LV) segments and to find correlations between them and cardiovascular risk factors. The 233 asymptomatic subjects (210 men, 23 women; aged 54.1 ± 6.0 years) underwent cardiac magnetic resonance imaging with preT1 and postT1 mapping on a 1.5-T scanner. T1 values and ECVs were evaluated according to LV segments, age, sex, and estimated glomerular filtration rate (eGFR). Based on the presence of hypertension (HTN) and diabetes mellitus (DM), subjects were subdivided into the control, HTN, DM, and HTN and DM (HTN-DM) groups. T1 values and ECV showed significant differences between septal and lateral segments at the mid-ventricular and basal levels (p ≤ 0.003). In subgroup analysis, the HTN-DM group showed a significantly higher ECV (0.260 ± 0.023) than the control (0.240 ± 0.021, p = 0.011) and HTN (0.241 ± 0.024, p = 0.041) groups. Overall postT1 and ECV of the LV had significant correlation with eGFR (r = 0.19, p = 0.038 for postT1; r =  − 0.23, p = 0.011 for ECV). Septal segments show higher preT1 and ECV but lower postT1 than lateral segments at the mid-ventricular and basal levels. ECV is significantly affected by HTN, DM, and eGFR, even in asymptomatic subjects.

Multi-modality cardiac imaging in the management of diabetic heart disease

Diabetic heart disease is a major healthcare problem. Patients with diabetes show an excess of death from cardiovascular causes, twice as high as the general population and those with diabetes type 1 and longer duration of the disease present with more severe cardiovascular complications. Premature coronary artery disease and heart failure are leading causes of morbidity and reduced life expectancy. Multimodality cardiac imaging, including echocardiography, cardiac computed tomography, nuclear medicine, and cardiac magnetic resonance play crucial role in the diagnosis and management of different pathologies included in the definition of diabetic heart disease. In this review we summarise the utility of multi-modality cardiac imaging in characterising ischaemic and non-ischaemic causes of diabetic heart disease and give an overview of the current clinical practice. We also describe emerging imaging techniques enabling early detection of coronary artery inflammation and the non-invasive characterisation of the atherosclerotic plaque disease. Furthermore, we discuss the role of MRI-derived techniques in studying altered myocardial metabolism linking diabetes with the development of diabetic cardiomyopathy. Finally, we discuss recent data regarding the use of artificial intelligence applied to large imaging databases and how those efforts can be utilised in the future in screening of patients with diabetes for early signs of disease.

Cardiac magnetic resonance T1 mapping for evaluating myocardial fibrosis in patients with type 2 diabetes mellitus: correlation with left ventricular longitudinal diastolic dysfunction

OBJECTIVES

We aimed to evaluate myocardial fibrosis using cardiac magnetic resonance (CMR) T1 mapping in type 2 diabetes mellitus (T2DM) patients and investigate the association between left ventricular (LV) subclinical myocardial dysfunction and myocardial fibrosis.

METHODS

The study included 37 short-term (≤ 5 years) and 44 longer-term (> 5 years) T2DM patients and 41 healthy controls. The LV global strain parameters and T1 mapping parameters were compared between the abovementioned three groups. The association of T1 mapping parameters with diabetes duration, in addition to other risk factors, was determined using multivariate linear regression analysis. The correlation between LV strain parameters and T1 mapping parameters was evaluated using Pearson's correlation.

RESULTS

The peak diastolic strain rates (PDSRs) were significantly lower in longer-term T2DM patients compared to those in healthy subjects and short-term T2DM patients (p < 0.05). The longitudinal peak systolic strain rate and peak strain were significantly lower in the longer-term T2DM compared with the short-term T2DM group (p < 0.05). The extracellular volumes (ECVs) were higher in both subgroups of T2DM patients compared with control subjects (all p < 0.05). Multivariate linear regression analysis showed that diabetes duration was independently associated with ECV (β = 0.413, p < 0.001) by taking covariates into account. Pearson's analysis showed that ECV was associated with longitudinal PDSR (r = - 0.441, p < 0.001).

CONCLUSION

T1 mapping could detect abnormal myocardial fibrosis early in patients with T2DM, which can cause a decline in the LV diastolic function.

KEY POINTS

• CMR T1 mapping could detect abnormal myocardial fibrosis early in patients with T2DM. • The diabetes duration was independently associated with ECV. • Myocardial fibrosis can cause a decline in the LV diastolic function in T2DM patients.

Using different geometries to modulate the cardiac fibroblast phenotype and the biomechanical properties of engineered connective tissues

Tissue engineering with human cardiac fibroblasts (CF) allows identifying novel mechanisms and anti-fibrotic drugs in the context of cardiac fibrosis. However, substantial knowledge on the influences of the used materials and tissue geometries on tissue properties and cell phenotypes is necessary to be able to choose an appropriate model for a specific research question. As there is a clear lack of information on how CF react to the mold architecture in engineered connective tissues (ECT), we first compared the effect of two mold geometries and materials with different hardnesses on the biomechanical properties of ECT. We could show that ECT, which formed around two distant poles (non-uniform model) were less stiff and more strain-resistant than ECT, which formed around a central rod (uniform model), independent of the materials used for poles and rods. Next, we investigated the cell state and could demonstrate that in the uniform versus non-uniform model, the embedded cells have a higher cell cycle activity and display a more pronounced myofibroblast phenotype. Differential gene expression analysis revealed that uniform ECT displayed a fibrosis-associated gene signature similar to the diseased heart. Furthermore, we were able to identify important relationships between cell and tissue characteristics, as well as between biomechanical tissue parameters by implementing cells from normal heart and end-stage heart failure explants from patients with ischemic or dilated cardiomyopathy. Finally, we show that the application of pro- and anti-fibrotic factors in the non-uniform and uniform model, respectively, is not sufficient to mimic the effect of the other geometry. Taken together, we demonstrate that modifying the mold geometry in tissue engineering with CF offers the possibility to compare different cellular phenotypes and biomechanical tissue properties.

Cardiac Magnetic Resonance Imaging Techniques and Applications for Pericardial Diseases

Cardiac magnetic resonance imaging plays a central role among multimodality imaging modalities in the assessment, diagnosis, and surveillance of pericardial diseases. Clinicians and imagers should have a foundational understanding of the utilities, advantages, and limitations of cardiac magnetic resonance imaging and how they integrate with other diagnostic tools involved in the evaluation and management of pericardial diseases. This review aims to outline the contemporary magnetic resonance imaging sequences used to evaluate the pericardium, followed by exploring the main clinical applications of magnetic resonance imaging for identifying pericardial inflammation, constriction, and effusion.

Guidelines on Models of Diabetic Heart Disease

Diabetes is a major risk factor for cardiovascular diseases, including diabetic cardiomyopathy, atherosclerosis, myocardial infarction, and heart failure. As cardiovascular disease represents the number one cause of death in people with diabetes, there has been a major emphasis on understanding the mechanisms by which diabetes promotes cardiovascular disease, and how antidiabetic therapies impact diabetic heart disease. With a wide array of models to study diabetes (both type 1 and type 2), the field has made major progress in answering these questions. However, each model has its own inherent limitations. Therefore, the purpose of this guidelines document is to provide the field with information on which aspects of cardiovascular disease in the human diabetic population are most accurately reproduced by the available models. This review aims to emphasize the advantages and disadvantages of each model, and to highlight the practical challenges and technical considerations involved. We will review the preclinical animal models of diabetes (based on their method of induction), appraise models of diabetes-related atherosclerosis and heart failure, and discuss in vitro models of diabetic heart disease. These guidelines will allow researchers to select the appropriate model of diabetic heart disease, depending on the specific research question being addressed.

Lipids and diastolic dysfunction: Recent evidence and findings

AIM

Diastolic dysfunction is the decreased flexibility of the left ventricle due to the impaired ability of the myocardium to relax and plays an important role in the pathogenesis of heart failure. Lipid metabolism is a well-known contributor to cardiac conditions, including ventricular function. In this article, we aimed to review the literature addressing the connections between lipids, their storage, and metabolism with left ventricular diastolic dysfunction.

DATA SYNTHESIS

We searched Google scholar, Pubmed, Embase and Researchgate for our keywords: "Diastolic function", "Fat" and "Lipid profile". Initially, 250 articles were selected by title and 84 of them were chosen as most relevant and directly reviewed.

CONCLUSIONS

Alterations of lipid metabolism in cardiac muscle and cardiac lipid content can occur in many conditions, including consumption of a high-fat diet, obesity, metabolic syndrome, and non-alcoholic fatty liver disease (NAFLD). These conditions induce alterations in myocardial lipid metabolism, increase myocardial fat content and epicardial fat thickness and increase inflammation and oxidative stress which ultimately lead to cardiac lipotoxicity and diastolic dysfunction. The effects of lipids on diastolic function can differ based on gender. Lipid profile and metabolism are as important in the pathogenesis of diastolic dysfunction as they are in other cardiovascular disorders. A more careful look at cardiac lipid metabolism in molecular, histological and gross levels results in more precise understanding of its role in myocardial function and leads to development of potential treatments for diastolic dysfunction.

Association between myocardial fibrosis, as assessed with cardiac magnetic resonance T1 mapping, and persistent dyspnea after pulmonary embolism

Background

Persistent dyspnea is a common symptom after pulmonary embolism (PE). However, the pathophysiology of persistent dyspnea is not fully clarified. This study aimed to explore possible associations between diffuse myocardial fibrosis, as assessed by cardiac magnetic resonance (CMR) T1 mapping, and persistent dyspnea in patients with a history of PE.

Methods

CMR with T1 mapping and extracellular volume fraction (ECV) calculations were performed after PE in 51 patients with persistent dyspnea and in 50 non-dyspneic patients. Patients with known pulmonary disease, heart disease and CTEPH were excluded.

Results

Native T1 was higher in the interventricular septum in dyspneic patients compared to non-dyspneic patients; difference 13 ms (95% CI: 2–23 ms). ECV was also significantly higher in patients with dyspnea; difference 0.9 percent points (95% CI: 0.04–1.8 pp). There was no difference in native T1 or ECV in the left ventricular lateral wall. Native T1 in the interventricular septum had an adjusted Odds Ratio of 1.18 per 10 ms increase (95% CI: 0.99–1.42) in predicting dyspnea, and an adjusted Odds Ratio of 1.47 per 10 ms increase (95% CI: 1.10–1.96) in predicting Incremental Shuttle Walk Test (ISWT) score < 1020 m.

Conclusion

Septal native T1 and ECV values were higher in patients with dyspnea after PE compared with those who were fully recovered suggesting a possible pathological role of myocardial fibrosis in the development of dyspnea after PE. Further studies are needed to validate our findings and to explore their pathophysiological role and clinical significance.

Diabetic cardiomyopathy: Clinical phenotype and practice

Diabetic cardiomyopathy (DCM) is a pathophysiological condition of cardiac structure and function changes in diabetic patients without coronary artery disease, hypertension, and other types of heart diseases. DCM is not uncommon in people with diabetes, which increases the risk of heart failure. However, the treatment is scarce, and the prognosis is poor. Since 1972, one clinical study after another on DCM has been conducted. However, the complex phenotype of DCM still has not been fully revealed. This dilemma hinders the pace of understanding the essence of DCM and makes it difficult to carry out penetrating clinical or basic research. This review summarizes the literature on DCM over the last 40 years and discusses the overall perspective of DCM, phase of progression, potential clinical indicators, diagnostic and screening criteria, and related randomized controlled trials to understand DCM better.

Cardiac Magnetic Resonance Radiomics Reveal Differential Impact of Sex, Age, and Vascular Risk Factors on Cardiac Structure and Myocardial Tissue

Background: Cardiovascular magnetic resonance (CMR) radiomics analysis provides multiple quantifiers of ventricular shape and myocardial texture, which may be used for detailed cardiovascular phenotyping. Objectives: We studied variation in CMR radiomics phenotypes by age and sex in healthy UK Biobank participants. Then, we examined independent associations of classical vascular risk factors (VRFs: smoking, diabetes, hypertension, high cholesterol) with CMR radiomics features, considering potential sex and age differential relationships. Design: Image acquisition was with 1.5 Tesla scanners (MAGNETOM Aera, Siemens). Three regions of interest were segmented from short axis stack images using an automated pipeline: right ventricle, left ventricle, myocardium. We extracted 237 radiomics features from each study using Pyradiomics. In a healthy subset of participants (n = 14,902) without cardiovascular disease or VRFs, we estimated independent associations of age and sex with each radiomics feature using linear regression models adjusted for body size. We then created a sample comprising individuals with at least one VRF matched to an equal number of healthy participants (n = 27,400). We linearly modelled each radiomics feature against age, sex, body size, and all the VRFs. Bonferroni adjustment for multiple testing was applied to all p-values. To aid interpretation, we organised the results into six feature clusters. Results: Amongst the healthy subset, men had larger ventricles with dimmer and less texturally complex myocardium than women. Increasing age was associated with smaller ventricles and greater variation in myocardial intensities. Broadly, all the VRFs were associated with dimmer, less varied signal intensities, greater uniformity of local intensity levels, and greater relative presence of low signal intensity areas within the myocardium. Diabetes and high cholesterol were also associated with smaller ventricular size, this association was of greater magnitude in men than women. The pattern of alteration of radiomics features with the VRFs was broadly consistent in men and women. However, the associations between intensity based radiomics features with both diabetes and hypertension were more prominent in women than men. Conclusions: We demonstrate novel independent associations of sex, age, and major VRFs with CMR radiomics phenotypes. Further studies into the nature and clinical significance of these phenotypes are needed.

Resting Left Ventricular Global Longitudinal Strain to Identify Silent Myocardial Ischemia in Asymptomatic Patients with Diabetes Mellitus

BACKGROUND

Screening for silent coronary artery disease in asymptomatic patients with diabetes mellitus (DM) is challenging and controversial. In this context, it seems crucial to identify early markers of coronary artery disease.

METHODS

The aim of this study was to investigate the incremental value of resting left ventricular (LV) global longitudinal strain (GLS) for the prediction of positive results on stress (exercise or dobutamine) transthoracic echocardiography in 273 consecutive asymptomatic high-risk patients with DM. Positive results on stress transthoracic echocardiography were defined as stress-induced LV wall motion abnormalities (new or worsening preexisting abnormalities).

RESULTS

Compared with patients with negative stress results, those with positive stress results (n = 28 [10%]) more frequently had cardiovascular risk factors, complications of DM, vascular disease, moderate and severe calcification of the aortic valve and mitral annulus, and worse resting LV GLS (-16.7 ± 2.9% vs -19.0 ± 1.9%, P < .001). On multivariable logistic regression analysis, DM duration > 10 years, diabetic retinopathy, LV hypertrophy, and impaired LV GLS (odds ratio, 1.39 [95% CI, 1.14-1.70] per percentage increase; odds ratio, 5.16 [95% CI, 1.96-13.59] for LV GLS worse than -18%) were independently associated with positive results on stress transthoracic echocardiography. The area under the curve to predict positive results was 0.74 for LV GLS with a cutoff of -18.0% (sensitivity 68%, specificity 78%). The area under the curve of the multivariable model to predict test results was improved by the addition of LV GLS (P < .001), with a bias-corrected area under the curve after bootstrapping of 0.842 [95% CI, 0.753-0.893].

CONCLUSIONS

The present findings show that resting LV GLS is associated with the presence of silent ischemia and could be useful to better identify asymptomatic patients with DM who might benefit from coronary artery disease screening.

Fibrosis of the diabetic heart: Clinical significance, molecular mechanisms, and therapeutic opportunities

In patients with diabetes, myocardial fibrosis may contribute to the pathogenesis of heart failure and arrhythmogenesis, increasing ventricular stiffness and delaying conduction. Diabetic myocardial fibrosis involves effects of hyperglycemia, lipotoxicity and insulin resistance on cardiac fibroblasts, directly resulting in increased matrix secretion, and activation of paracrine signaling in cardiomyocytes, immune and vascular cells, that release fibroblast-activating mediators. Neurohumoral pathways, cytokines, growth factors, oxidative stress, advanced glycation end-products (AGEs), and matricellular proteins have been implicated in diabetic fibrosis; however, the molecular links between the metabolic perturbations and activation of a fibrogenic program remain poorly understood. Although existing therapies using glucose- and lipid-lowering agents and neurohumoral inhibition may act in part by attenuating myocardial collagen deposition, specific therapies targeting the fibrotic response are lacking. This review manuscript discusses the clinical significance, molecular mechanisms and cell biology of diabetic cardiac fibrosis and proposes therapeutic targets that may attenuate the fibrotic response, preventing heart failure progression.

Assessing left ventricular systolic function: from ejection fraction to strain analysis

The measurement of left ventricular ejection fraction (LVEF) is a ubiquitous component of imaging studies used to evaluate patients with cardiac conditions and acts as an arbiter for many management decisions. This follows early trials investigating heart failure therapies which used a binary LVEF cut-off to select patients with the worst prognosis, who may gain the most benefit. Forty years on, the cardiac disease landscape has changed. Left ventricular ejection fraction is now a poor indicator of prognosis for many heart failure patients; specifically, for the half of patients with heart failure and truly preserved ejection fraction (HF-PEF). It is also recognized that LVEF may remain normal amongst patients with valvular heart disease who have significant myocardial dysfunction. This emphasizes the importance of the interaction between LVEF and left ventricular geometry. Guidelines based on LVEF may therefore miss a proportion of patients who would benefit from early intervention to prevent further myocardial decompensation and future adverse outcomes. The assessment of myocardial strain, or intrinsic deformation, holds promise to improve these issues. The measurement of global longitudinal strain (GLS) has consistently been shown to improve the risk stratification of patients with heart failure and identify patients with valvular heart disease who have myocardial decompensation despite preserved LVEF and an increased risk of adverse outcomes. To complete the integration of GLS into routine clinical practice, further studies are required to confirm that such approaches improve therapy selection and accordingly, the outcome for patients.

Empagliflozin Reduces Myocardial Extracellular Volume in Patients With Type 2 Diabetes and Coronary Artery Disease

OBJECTIVES

This study sought to evaluate the effects of empagliflozin on extracellular volume (ECV) in individuals with type 2 diabetes mellitus (T2DM) and coronary artery disease (CAD).

BACKGROUND

Empagliflozin has been shown to reduce left ventricular mass index (LVMi) in patients with T2DM and CAD. The effects on myocardial ECV are unknown.

METHODS

This was a prespecified substudy of the EMPA-HEART (Effects of Empagliflozin on Cardiac Structure in Patients with Type 2 Diabetes) CardioLink-6 trial in which 97 participants were randomized to receive empagliflozin 10 mg daily or placebo for 6 months. Data from 74 participants were included: 39 from the empagliflozin group and 35 from the placebo group. The main outcome was change in left ventricular ECV from baseline to 6 months determined by cardiac magnetic resonance (CMR). Other outcomes included change in LVMi, indexed intracellular compartment volume (iICV) and indexed extracellular compartment volume (iECV), and the fibrosis biomarkers soluble suppressor of tumorgenicity (sST2) and matrix metalloproteinase (MMP)-2.

RESULTS

Baseline ECV was elevated in the empagliflozin group (29.6 ± 4.6%) and placebo group (30.6 ± 4.8%). Six months of empagliflozin therapy reduced ECV compared with placebo (adjusted difference: -1.40%; 95% confidence interval [CI]: -2.60 to -0.14%; p = 0.03). Empagliflozin therapy reduced iECV (adjusted difference: -1.5 ml/m²; 95% CI: -2.6 to -0.5 ml/m²; p = 0.006), with a trend toward reduction in iICV (adjusted difference: -1.7 ml/m²; 95% CI: -3.8 to 0.3 ml/m²; p = 0.09). Empagliflozin had no impact on MMP-2 or sST2.

CONCLUSIONS

In individuals with T2DM and CAD, 6 months of empagliflozin reduced ECV, iECV, and LVMi. No changes in MMP-2 and sST2 were seen. Further investigation into the mechanisms by which empagliflozin causes reverse remodeling is required. (Effects of Empagliflozin on Cardiac Structure in Patients With Type 2 Diabetes [EMPA-HEART]; NCT02998970).

CMR-Verified Myocardial Fibrosis Is Associated With Subclinical Diastolic Dysfunction in Primary Aldosteronism Patients

OBJECTIVES

The main cardiac features of primary aldosteronism (PA) are impaired left ventricular (LV) diastolic function, and some articles also reported more cardiac fibrosis in PA patients. However, the correlation between LV dysfunction and diffuse myocardial fibrosis in PA remains unknown.

METHODS

We enrolled 84 PA patients and 28 essential hypertension (EH) patients in West China Hospital. Cardiac magnetic resonance imaging (CMR) contrast enhancement was arranged for all subjects. Postcontrast T1 time and left ventricular myocardial strains and strain rates were measured.

RESULTS

76 PA patients and 27 essential hypertension (EH) patients were included in the final analysis. Blood pressure, LV mass indexes, and LV ejection fractions were comparable in both groups, while the global circumferential peak diastolic strain rate (PDSR) was lower (0.9 ± 0.3 vs. 1.1 ± 0.4, p <0.01) and the postcontrast T1 time was shorter (520 ± 38 vs. 538 ± 27, p = 0.01) in PA patients than those in EH patients. Postcontrast T1 time (p = 0.01) was independently related to global circumferential PDSR after adjusting for age and duration of hypertension in PA patients. Furthermore, plasma aldosterone concentration was negatively associated with postcontrast T1 time (R = -0.253, p = 0.028) in PA patients.

CONCLUSIONS

The global circumferential PDSR derived by CMR is decreased, and the diffuse myocardial fibrosis is increased in PA patients compared to those in blood pressure matched EH patients. The severity of cardiac diastolic dysfunction independently relates to the degree of diffuse myocardial fibrosis in PA patients, and the diffuse myocardial fibrosis may be caused by high PAC level.

CLINICAL TRIAL REGISTRATION

http://www.chictr.org.cn/listbycreater.asp, identifier ChiCTR2000031792.

RADIOTHERAPY-ASSOCIATED CARDIOVASCULAR COMPLICATIONS IN CANCER (review)

The review is devoted to the current issues of radiation-induced cardiovascular complications, their diagnostics andincidence depending on the radiation doses and exposure regimens, potential efficiency of the screening strategiesfor cardiotoxicity monitoring after radiotherapy in cancer patients by analyzing the data from literature and clinical trials, based on recommendations of European Society of Cardiology and European Society of Medical Oncology.

Diabesity: the combined burden of obesity and diabetes on heart disease and the role of imaging

Diabesity is a term used to describe the combined adverse health effects of obesity and diabetes mellitus. The worldwide dual epidemic of obesity and type 2 diabetes is an important public health issue. Projections estimate a sixfold increase in the number of adults with obesity in 40 years and an increase in the number of individuals with diabetes to 642 million by 2040. Increased adiposity is the strongest risk factor for developing diabetes. Early detection of the effects of diabesity on the cardiovascular system would enable the optimal implementation of effective therapies that prevent atherosclerosis progression, cardiac remodelling, and the resulting ischaemic heart disease and heart failure. Beyond conventional imaging techniques, such as echocardiography, CT and cardiac magnetic resonance, novel post-processing tools and techniques provide information on the biological processes that underlie metabolic heart disease. In this Review, we summarize the effects of obesity and diabetes on myocardial structure and function and illustrate the use of state-of-the-art multimodality cardiac imaging to elucidate the pathophysiology of myocardial dysfunction, prognosticate long-term clinical outcomes and potentially guide treatment strategies.

Diabetic cardiomyopathy: How can cardiac magnetic resonance help?

Diabetes cardiomyopathy is a specific form of cardiac disease characteristic for diabetic patients. Development of echocardiography enabled diagnosis of diabetic cardiomyopathy significantly before the occurrence of heart failure. Previously was believed that left ventricular (LV) diastolic dysfunction represents the first detectable stage of diabetic cardiomyopathy. However, speckle tracking imaging and strain evaluation showed that mechanical changes occur before LV diastolic dysfunction. Nevertheless, it seems that the first detectable stage of diabetic cardiomyopathy is myocardial interstitial fibrosis, which currently could be diagnosed predominantly by cardiac magnetic resonance. T1 mapping evaluation before and after contrast injection enables assessment of extracellular volume (ECV) and provides qualitative and quantitative assessment of interstitial myocardial fibrosis in diabetic patients. Studies showed a strong correlation between ECV-parameter of interstitial fibrosis and level of glycated hemoglobin-main parameter of glucose control in diabetes. This stage of fibrosis is still not LV hypertrophy and it is reversible, which is of a great importance because of timely initiation of treatment. The necessity for early diagnose is significantly increasing due to the fact that diabetes and arterial hypertension are concomitant disorders in the large number of diabetic patients and it has been known that the risk of interstitial myocardial fibrosis is multiplied in patients with both conditions. Future follow-up investigations are essential to determine the causal relationship between interstitial fibrosis and outcome in these patients. The aim of this review was to summarize the current knowledge and clinical usefulness of CMR in diabetic patients.

Cardiac MRI utilizing late gadolinium enhancement (LGE) and T1 mapping in the detection of radiation induced heart disease

Background and purpose

Radiotherapy has been associated with late dose-dependent cardiovascular toxicity. In this cross-sectional pilot study, radiation dose distributions were correlated with areas of localized and diffuse myocardial fibrosis as measured by novel cardiac MRI (CMR) sequences including late gadolinium enhancement (LGE) and T1 mapping with the goal to identify early markers of myocardial damage.

Materials and methods

Twenty-eight patients with chest tumors including lung, breast, esophagus, and lymphoma underwent CMR per study protocol on average 46.4 months (range 1.7–344.5) after radiotherapy. Patients without pretreatment cardiac history were included if the volume of heart receiving 5 Gy or more was at least 10% (V5Gy ≥ 10%). The association of LGE with cardiac dosimetric factors, clinical factors (e.g., tumor type, smoking history, BMI), and T1 values was analyzed.

Results

Cardiac maximum (Dmax) and mean dose (Dmean) equivalent to doses delivered in 2 Gy fractions (EQD2) were on average 50.9 Gy (range 6.2–108.0) and 8.2 Gy (range 1.0–35.7), respectively, compared to 60.8 Gy (40.8–108.0) and 6.8 Gy (1.8–21.8) among the 9 patients with LGE. Doses were not different between patients with and without LGE (p = 0.16 and 0.56, respectively). The average T1 value of the left ventricle myocardium was 1009 ms (range 933–1117). No significant correlation was seen for heart Dmax and Dmean and T1 values (p = 0.14 and 0.58, respectively). In addition, no significant association between clinical factors and the development of LGE was identified.

Conclusions

No relation between cardiac doses, the presence of LGE or T1 values was observed. Further study is needed to determine the benefit of CMR for detecting radiotherapy-related myocardial fibrosis.

Association between fragmented QRS complexes and left-ventricular dysfunction in anabolic androgenic steroid users

Background: Anabolic androgen steroid (AS) use has adverse effects on left ventricular functions, such as fibrosis development. Fragmented QRS is an important marker of myocardial fibrosis, while speckle-tracking echocardiographyis a method used to show subclinical left ventricle dysfunction. In this study, we examined the the ability of fQRS + to detect left ventricle fibrosis by speckle tracking echocardiography (STE) in AS users.Methods: The study included a total of 181 healthy athletes. Athletes were divided into two groups as AS users (n = 89) and non-AS users (n = 92). Then, athletes using AS were divided into two groups as fQRS+ (n = 52) and fQRS- (n = 37). In both groups, the arithmetic mean of three images was used to obtain the left ventricle global longitudinal strain (LV-GLS). The E/SRe ratio was also calculated and analysed.Results: There were significant differences between the AS users and non-AS users in terms of, E/SRe (55.7 ± 17.9 vs 50.3 ± 14.8; p = 0.015), LV-GLS (23.1 ± 1.9 vs 24.0 ± 1.7; p = 0.001), and fQRS (18.5% vs 6%; p = 0.005). When subgroup analysis was performed, both LV-GLS and E/SRivr were found to be poor in the fQRS + group. When multiple linear regression analysis was performed, we determined fQRS as an independent predictor for LV-GLS and E/SRivr ratio.Conclusion: In conclusion, our study demonstrated that fQRS is a parameter that can beused to determine left ventricle subclinical systolic and diastolic dysfunction in AS users. It can be used for cessation of drug use, especially in long-term use.

Impact of Epicardial Adipose Tissue, Left Ventricular Myocardial Fat Content, and Interstitial Fibrosis on Myocardial Contractile Function

Background Current understanding of metabolic heart disease consists of a myriad of different pathophysiological mechanisms. Epicardial adipose tissue (EAT) is increasingly recognized as metabolically active and associated with adverse cardiovascular outcomes. The present study aimed to investigate the effect of increased EAT volume index on left ventricular (LV) myocardial fat content and burden of interstitial myocardial fibrosis and their subsequent effects on LV myocardial contractile function. Methods and Results A total of 40 volunteers (mean age, 35±10 years; 26 males) of varying body mass index (25.0±4.1 kg/m²; range, 19.3-36.3 kg/m²) and without diabetes mellitus or hypertension were prospectively recruited. EAT volume index, LV myocardial fat content, and extracellular volume were quantified by magnetic resonance imaging. LV myocardial contractile function was quantified by speckle tracking echocardiography global longitudinal strain on the same day as magnetic resonance imaging examination. Mean total EAT volume index, LV myocardial fat content, and extracellular volume were 30.0±19.6 cm³/m², 5.06%±1.18%, and 27.5%±0.5%, respectively. On multivariable analyses, increased EAT volume index and insulin resistance were independently associated with both increased LV myocardial fat content content and higher burden of interstitial myocardial fibrosis. Furthermore, increased EAT volume index was independently associated with LV global longitudinal strain. Conclusions Increased EAT volume index and insulin resistance were independently associated with increased myocardial fat accumulation and interstitial myocardial fibrosis. Increased EAT volume index was associated with detrimental effects on myocardial contractile function as evidenced by a reduction in LV global longitudinal strain.

Myocardial native-T1 times are elevated as a function of hypertrophy, HbA1c, and heart rate in diabetic adults without diffuse fibrosis

PURPOSE

Cardiac native-T1 times have correlated to extracellular volume fraction in patients with confirmed fibrosis. However, whether other factors that can occur either alongside or independently of fibrosis including increased intracellular water volume, altered magnetization transfer (MT), or glycation of hemoglobin, lengthen T1 times in the absence of fibrosis remains unclear. The current study examined whether native-T1 times are elevated in hypertrophic diabetics with elevated hemoglobin A1C (HbA1c) without diffuse fibrosis.

METHODS

Native-T1 times were quantified in 27 diabetic and 10 healthy adults using a modified Look-Locker imaging (MOLLI) sequence at 1.5 T. The MT ratio (MTR) was quantified using dual flip angle cine balanced steady-state free precession. Gadolinium (0.2 mmol/kg Gd-DTPA) was administered as a bolus and post-contrast T1-times were quantified after 15 min. Means were compared using a two-tailed student's t-test, while correlations were assessed using Pearson's correlations.

RESULTS

While left ventricular volumes, ejection fraction, and cardiac output were similar between groups, left ventricular mass and mass-to-volume ratio (MVR) were significantly higher in diabetic adults. Mean ECV (0.25 ± 0.02 Healthy vs. 0.25 ± 0.03 Diabetic, P = 0.47) and MTR (125 ± 16% Healthy vs. 125 ± 9% Diabetic, P = 0.97) were similar, however native-T1 times were significantly higher in diabetics (1016 ± 21 ms Healthy vs. 1056 ± 31 ms Diabetic, P = 0.00051). Global native-T1 times correlated with MVR (ρ = 0.43, P = 0.008) and plasma HbA1c levels (ρ = 0.43, P = 0.0088) but not ECV (ρ = 0.06, P = 0.73). Septal native-T1 times correlated with septal wall thickness (ρ = 0.50, P = 0.001).

CONCLUSION

In diabetic adults with normal ECV values, elevated native-T1 times may reflect increased intracellular water volume and changes secondary to increased hemoglobin glycation.

Non-Invasive Imaging in Diabetic Cardiomyopathy

There is increasing recognition of a specific diabetic cardiomyopathy beyond ischemic cardiomyopathy, which leads to structural and functional myocardial abnormalities. The aim of this review is to summarize the recent literature on diagnostic findings and prognostic significance of non-invasive imaging including echocardiography, nuclear imaging, computed tomography and cardiovascular magnetic resonance in diabetic cardiomyopathy.

Diabetic cardiomyopathy: prevalence, determinants and potential treatments

The prevalence of type 2 diabetes (T2D) has reached a pandemic scale. These patients are at a substantially elevated risk of developing cardiovascular disease, with heart failure (HF) being a leading cause of morbidity and mortality. Even in the absence of traditional risk factors, diabetes still confers up to a twofold increased risk of developing HF. This has led to identifying diabetes as an independent risk factor for HF and recognition of the distinct clinical entity, diabetic cardiomyopathy. Despite a wealth of research interest, the prevalence and determinants of diabetic cardiomyopathy remain uncertain. This limited understanding of the pathophysiology of diabetic heart disease has also hindered development of effective treatments. Tight blood-glucose and blood-pressure control have not convincingly been shown to reduce macrovascular outcomes in T2D. There is, however, emerging evidence that T2D is reversible and that the metabolic abnormalities can be reversed with weight loss. Increased aerobic exercise capacity is associated with significantly lower cardiovascular and overall mortality in diabetes. Whether such lifestyle modifications as weight loss and exercise may ameliorate the structural and functional derangements of the diabetic heart has yet to be established. In this review, the link between T2D and myocardial dysfunction is explored. Insights into the structural and functional perturbations that typify the diabetic heart are first described. This is followed by an examination of the pathophysiological mechanisms that contribute to the development of cardiovascular disease in T2D. Lastly, the current and emerging therapeutic strategies to prevent or ameliorate cardiac dysfunction in T2D are evaluated.

Myocardial tissue characterization by contrast-enhanced cardiac magnetic resonance imaging in subjects with prediabetes, diabetes, and normal controls with preserved ejection fraction from the general population

Aims

To characterize changes in the myocardium in subjects with prediabetes, diabetes, and healthy controls with preserved left ventricular ejection fraction (LVEF) by using cardiac magnetic resonance imaging (CMR) in a sample from the general population.

Methods and results

Subjects without history of cardiovascular disease and preserved LVEF but established diabetes, prediabetes, and controls from a population-based cohort underwent contrast-enhanced CMR. Obtained parameters included left ventricular (LV) function and morphology, late gadolinium enhancement as well as T1-mapping and derivation of extracellular volume fraction (ECV) by modified Look-Locker inversion recovery for diffuse fibrosis in a subset of patients. Fibrosis volume and cell volume were calculated and LV remodelling index was calculated by dividing the LV mass by its end-diastolic volume. Among 343 subjects (56.1 ± 9.2 years, 57% males), 47 subjects were classified as diabetes, 78 as prediabetes, and 218 as controls. Haematocrit values and thus ECV parameters were available in 251 subjects. LV remodelling index was significantly higher in participants with prediabetes and diabetes, independent of body mass index (BMI), hypertension, age, and sex. ECV was decreased in subjects with prediabetes and diabetes compared with healthy controls (23.1 ± 2.4% and 22.8 ± 3.0%, both P < 0.007). In contrast, cell volume was significantly higher in subjects with prediabetes and diabetes as compared with controls (109.1 ± 23.8 and 114.9 ± 32.3 mL vs. 96.5 ± 26.9 mL, both P < 0.03, respectively). However, differences in ECV and cell volume attenuated after the adjustment for cardiometabolic risk factors, including age, sex, BMI, and hypertension.

Conclusion

Subjects with prediabetes and diabetes but preserved LVEF had higher LV remodelling indices, suggesting early detectable changes in the disease process, while diffuse myocardial fibrosis appears to be less relevant at this stage.

Relationship Between Focal and Diffuse Fibrosis Assessed by CMR and Clinical Outcomes in Heart Failure With Preserved Ejection Fraction

OBJECTIVES

This study sought to assess the presence and extent of focal and diffuse fibrosis in heart failure in patients with preserved ejection fraction (HFpEF) compared to asymptomatic control subjects, and the relationship of fibrosis to clinical outcome.

BACKGROUND

Myocardial fibrosis has been implicated in the pathophysiology of HFpEF.

METHODS

In this prospective, observational study, 140 subjects of similar age and sex (HFpEF: n = 96; control subjects: n = 44; 73 ± 8 years of age; 49% males) underwent cardiac magnetic resonance imaging. Late gadolinium-enhanced (LGE) imaging and T1 mapping to calculate myocardial extracellular volume indexed to body surface area (iECV) were used to assess fibrosis.

RESULTS

Patients with HFpEF had more concentric remodeling and worse diastolic function. Focal fibrosis was more frequent in HFpEF subjects (overall: n = 49; infarction: n = 17; nonischemic cases: n = 36; mixed patterns: n = 4) than in control subjects (overall: n = 3). Diffuse fibrosis was also greater in HFpEF subjects than control subjects (iECV: 13.7 ± 4.4 ml/m² versus 10.9 ± 2.8 ml/m²; p < 0.0001). During median follow-up (1,429 days), there were 42 composite events (14 deaths; 28 heart failure hospitalizations) in cases of HFpEF. Myocardial infarction revealed on LGE imaging was a predictor of outcomes on univariate analysis only. With multivariate analysis, iECV (hazard ratio [HR]: 1.689; 95% confidence interval [CI]: 1.141 to 2.501; p = 0.009) was an independent predictor of outcome along with mitral peak velocity of early filling (E)-to-early diastolic mitral annular velocity (E') (E/E') ratio (HR: 1.716; 95% CI: 1.191 to 2.472; p = 0.004) and prior HF hospitalization (HR: 2.537; 95% CI: 1.090 to 5.902; p = 0.031). iECV was also significantly associated with ventricular/left atrial remodeling and renal dysfunction: right ventricular end-diastolic volume indexed (r = 0.456; p < 0.0001), left ventricular mass/volume (r = 0.348; p = 0.001), maximal left atrial volume indexed (r = 0. 269; p = 0.009), and creatinine (r = 0.271; p = 0.009).

CONCLUSIONS

Both focal and diffuse myocardial fibrosis are more prevalent in HFpEF subjects than in control subjects of similar age and sex. iECV significantly correlates with indices of ventricular/left atrial remodeling and renal dysfunction and is an independent predictor of adverse outcome in HFpEF. (Developing Imaging And plasMa biOmarkers iN Describing Heart Failure With Preserved Ejection Fraction [DIAMONDHFpEF]; NCT03050593).

Innovative imaging methods in heart failure: a shifting paradigm in cardiac assessment. Position statement on behalf of the Heart Failure Association of the European Society of Cardiology

Myriad advances in all fields of cardiac imaging have stimulated and reflected new understanding of cardiac performance, myocardial damage and the mechanisms of heart failure. In this paper, the Heart Failure Association assesses the potential usefulness of innovative imaging modalities in enabling more precise diagnostic and prognostic evaluation, as well as in guiding treatment strategies. Many new methods have gradually penetrated clinical practice and are on their way to becoming a part of routine evaluation. This paper focuses on myocardial deformation and three-dimensional ultrasound imaging; stress tests for the evaluation of contractile and filling function; the progress of magnetic resonance techniques; molecular imaging and other sound innovations. The Heart Failure Association aims to highlight the ways in which paradigms have shifted in several areas of cardiac assessment. These include reassessing of the simplified concept of ejection fraction and implementation of the new parameters of cardiac performance applicable to all heart failure phenotypes; switching from two-dimensional to more accurate and reproducible three-dimensional ultrasound volumetric evaluation; greater tissue characterization via recently developed magnetic resonance modalities; moving from assessing cardiac function and congestion at rest to assessing it during stress; from invasive to novel non-invasive hybrid techniques depicting coronary anatomy and myocardial perfusion; as well as from morphometry to the imaging of pathophysiologic processes such as inflammation and apoptosis. This position paper examines the specific benefits of imaging innovations for practitioners dealing with heart failure aetiology, risk stratification and monitoring, and, in addition, for scientists involved in the development of future research.

Fragmented QRS complexes are associated with left ventricular dysfunction in patients with type-2 diabetes mellitus: a two-dimensional speckle tracking echocardiography study

Background: Heart failure may develop independently of coronary artery disease in diabetes mellitus (DM) patients. Fragmented QRS (fQRS) is a marker of myocardial fibrosis or scar tissue and is related to an increase in cardiovascular adverse events. In this study, we examined the utility of speckle tracking echocardiography (STE) in assessing LV function in DM patients with fQRS. Methods and Results: The current study included 178 consecutive patients diagnosed with type-2 DM. The patients included were separated into two groups: those with (n = 50) and without (n = 128) fQRS. The two groups were compared by obtaining LV strain values with STE. Statistically significant differences were also identified between fQRS(-) and fQRS (+) groups with respect to Lv-GLS (p < .001), maxLAVI (p = .020), minLAVI (p < .001), E velocity (p < .001), Em velocity (0.002), E/Em ratio (<0.001) SRe (p < .001), SRe/SRa ratio (p < .001), SRivr (p < .001) and E/SRivr ratio (p < .001). In the multiple linear regression analysis, fQRS (β = -2.077, p = .002) and DM duration (β = -0.216, p = .021) were identified as independent predictors of Lv-GLS. However, fQRS (β = 4.557, p = .001) and minLAVI (β = -2.198, p = .031) were also found to be independent predictors of E/SRivr. We also performed multiple logistic regression analysis and identified Lv-GLS (β = -0.557, p = .001), minLAVI (β = -0.769, p = .001), E/Em ratio (β = 0.650, p = .001) and E/SRivr (β = 0.105, p = .001) as independent predictors of fQRS. Conclusıons: The results of this study revealed that subclinical LV dysfunction was more common in diabetic patients with fQRS. Therefore, determination of fQRS could be an indicator of the diabetic CMP in patients with DM.

Prognostic implications of left ventricular global longitudinal strain in heart failure patients with narrow QRS complex treated with cardiac resynchronization therapy: a subanalysis of the randomized EchoCRT trial

Aim

Left ventricular (LV) global longitudinal strain (GLS) reflects LV systolic function and correlates inversely with the extent of LV myocardial scar and fibrosis. The present subanalysis of the Echocardiography Guided CRT trial investigated the prognostic value of LV GLS in patients with narrow QRS complex.

Methods and results

Left ventricular (LV) global longitudinal strain (GLS) was measured on the apical 2-, 4- and 3-chamber views using speckle tracking analysis. Measurement of baseline LV GLS was feasible in 755 patients (374 with cardiac resynchronization therapy (CRT)-ON and 381 with CRT-OFF). The median value of LV GLS in the overall population was 7.9%, interquartile range 6.2-10.1%. After a mean follow-up period of 19.4 months, 95 patients in the CRT-OFF group and 111 in the CRT-ON group reached the combined primary endpoint of all-cause mortality and heart failure hospitalization. Each 1% absolute unit decrease in LV GLS was independently associated with 11% increase in the risk to reach the primary endpoint (Hazard ratio 1.11; 95% confidence interval 95% 1.04-1.17, P < 0.001), after adjusting for ischaemic cardiomyopathy and randomization treatment among other clinically relevant variables. When categorizing patients according to quartiles of LV GLS, the primary endpoint occurred more frequently in patients in the lowest quartile (<6.2%) treated with CRT-ON vs. CRT-OFF (45.6% vs. 28.7%, P = 0.009) whereas, no differences were observed in patients with LV GLS ≥6.2% treated with CRT-OFF vs. CRT-ON (23.7% vs. 24.5%, respectively; P  = 0.62).

Conclusion

Low LV GLS is associated with poor outcome in heart failure patients with QRS width <130 ms, independent of randomization to CRT or not. Importantly, in the group of patients with the lowest LV GLS quartile, CRT may have a detrimental effect on clinical outcomes.

Caloric restriction lowers endocannabinoid tonus and improves cardiac function in type 2 diabetes

BACKGROUND/OBJECTIVES

Endocannabinoids (ECs) are associated with obesity and ectopic fat accumulation, both of which play a role in the development of cardiovascular disease (CVD) in type 2 diabetes (T2D). The effect of prolonged caloric restriction on ECs in relation to fat distribution and cardiac function is still unknown. Therefore, our aim was to investigate this relationship in obese T2D patients with coronary artery disease (CAD).

SUBJECTS/METHODS

In a prospective intervention study, obese T2D patients with CAD (n = 27) followed a 16 week very low calorie diet (VLCD; 450-1000 kcal/day). Cardiac function and fat accumulation were assessed with MRI and spectroscopy. Plasma levels of lipid species, including ECs, were measured using liquid chromatography-mass spectrometry.

RESULTS

VLCD decreased plasma levels of virtually all measured lipid species of the class of N-acylethanolamines including the EC anandamide (AEA; -15%, p = 0.016), without decreasing monoacylglycerols including the EC 2-arachidonoylglycerol (2-AG). Baseline plasma AEA levels strongly correlated with the volume of subcutaneous white adipose tissue (SAT; R2 = 0.44, p < 0.001). VLCD decreased the volume of SAT (-53%, p < 0.001), visceral white adipose tissue (VAT) (-52%, p < 0.001), epicardial white adipose tissue (-15%, p < 0.001) and paracardial white adipose tissue (-28%, p < 0.001). VLCD also decreased hepatic (-86%, p < 0.001) and myocardial (-33%, p < 0.001) fat content. These effects were accompanied by an increased left ventricular ejection fraction (54.8 ± 8.7-56.2 ± 7.9%, p = 0.016).

CONCLUSIONS

Caloric restriction in T2D patients with CAD decreases AEA levels, but not 2-AG levels, which is paralleled by decreased lipid accumulation in adipose tissue, liver and heart, and improved cardiovascular function. Interestingly, baseline AEA levels strongly correlated with SAT volume. We anticipate that dietary interventions are worthwhile strategies in advanced T2D, and that reduction in AEA may contribute to the improved cardiometabolic phenotype induced by weight loss.