Diastolic heart failure

Right Atrial Function and Right Ventricular Diastolic Function and Their Relation With Exercise Capacity in OSAS

BACKGROUND

Right ventricular (RV) diastolic function and right atrial (RA) function are poorly characterized in patients with obstructive sleep apnea syndrome (OSAS), but may influence exercise capacity. We aimed to evaluate RA function and RV diastolic function in OSAS and study their relationship with exercise capacity.

METHODS

Fifty-three patients with OSAS and thirty age- and gender-matched controls prospectively underwent echocardiography and cardiopulmonary exercise testing to investigate RV diastolic function, RA function, and exercise capacity.

RESULTS

Altered RV diastolic function in patients with severe OSAS was indicated by the increased tricuspid valve E/e' ratio (TV E/e'), isovolumic relaxation time (IVRT), and by the reduced RV TDI e' velocity. The TV E/e' correlated modestly with peak VO2 (r = -0.334, p < 0.01). Patients with severe OSAS exhibited impaired RA total emptying fraction, RA passive emptying fraction, and RA reservoir strain (RARS), with RARS being associated with peak oxygen uptake (VO2) (r = 0.451, p < 0.01 for reservoir function).

CONCLUSION

Altered RA function and RV diastolic function in patients with OSAS are associated with impaired exercise capacity. The correlation of RA function and RV diastolic function with exercise capacity suggests that it may be important to evaluate RA function and RV diastolic function in this population.

Equine exercise-induced pulmonary hemorrhage: the role of high left-heart pressures secondary to exercise-induced hypervolemia, and high inspiratory pressures

Exercise-induced pulmonary hemorrhage (EIPH) is common in racehorses. Stress failure of the blood-gas barrier causes EIPH when the transmural pulmonary capillary (Pcap)-alveolar pressure difference (Ptm) exceeds the barrier's stress failure threshold. Why Pcap increases is incompletely understood. We hypothesized that alterations in blood volume (BV) could affect left ventricular (LV) and pulmonary arterial wedge (PAW) pressures and Pcap, and correspondingly affect EIPH severity. Six thoroughbreds with EIPH exercised at the same treadmill speed (≈11.9 m/s [11.1, 12.2]; median [IQR]) before (≈119% V̇o2max; B), 2 h after 14 L depletion of blood (≈132% V̇o2max; D), and 2 h after reinfusing the blood (≈111% V̇o2max; R). LV, pulmonary arterial (PAP), PAW, and intrapleural (Ppl) pressures were measured throughout exercise. Pcap = (PAP + PAW)/2 and Ptm = (Pcap - Ppl). EIPH severity was assessed 60 min postexercise by tracheoendoscopy (EIPHgrade) and bronchoalveolar lavage erythrocyte number (BALRBC). A mixed-effect model and Tukey post hoc test analyzed the effects of BV changes on LV, PAW, Pcap, Ppl, Ptm, and EIPH. P ≤ 0.05 was significant. Peak intrapleural inspiratory pressure (PplI) was high (-41 mmHg), unaffected by changes in BV (P = 0.44), and did not contribute to fluctuations in Ptm and EIPH severity, whereas changes in BV did (EIPHgrade: P = 0.01, BALRBC: P = 0.003). EIPH prevalence was 100% with B and R but 50% with D. MaxPtm was not different between B (146 mmHg [140, 151]) and R (151 mmHg [137, 160]) but was lower for D (128 mmHg [127, 130]; B: P = 0.005, R: P = 0.02). Vascular pressures and Ppl fluctuated constantly during exercise and independently influenced Ptm. Left ventricular end diastolic (LVED) pressure was correlated with Ptm (rrm = 0.90, P = 0.03) and EIPH rrm = 0.82, P = 0.004). Exercise BV was strongly correlated with EIPH severity in racehorses (rrm = 0.86, P = 0.009).NEW & NOTEWORTHY Hypervolemia induced by the infusion of erythrocyte-rich blood stored in the spleen is normal in high-speed thoroughbred exercise and increases capillary-alveolar transmural pressure (Ptm), leading to exercise-induced pulmonary hemorrhage (EIPH). In this study, decreasing blood volume reduced Ptm and EIPH. Large negative inspiratory pressures also contribute to high Ptm and the occurrence of EIPH. Ptm is dynamic and oscillates constantly during exercise. A significant relationship existed between circulating blood volume and EIPH severity in racehorses.

Left ventricular diastolic dysfunction in patients with heart failure with mildly reduced ejection fraction

OBJECTIVE

This study investigates the prevalence and prognostic impact of diastolic dysfunction (DD) in patients hospitalized with heart failure (HF) with mildly reduced ejection fraction (HFmrEF) in sinus rhythm.

BACKGROUND

Data regarding the prognostic impact of DD in patients with HFmrEF is limited.

METHODS

From 2016 to 2022, all patients hospitalized with HFmrEF (i.e., left ventricular ejection fraction 41-49% and signs and/or symptoms of HF) were retrospectively included at one institution. Patients with DD were compared to patients without (i.e., non-DD), further risk stratification was performed according to the severity of DD. The primary endpoint was all-cause mortality at 30 months (interquartile range (IQR) 15-61 months), key secondary endpoint was rehospitalization for worsening HF.

RESULTS

From a total of 1154 patients (median age 68 years, 68% males) hospitalized with HFmrEF, concomitant DD was present in 72% (grade I: 56%, grade II: 14%, grade III: 2%). Patients with DD were older (71 years vs. 65 years; p = 0.001) and presented with higher rates of cardiovascular comorbidities. The presence of DD was not associated with the risk of long-term all-cause mortality (adjusted HR = 0.815; 95% CI 0.612-1.085; p = 0.161) or HF-related rehospitalization (adjusted HR = 0.736; 95% CI 0.442-1.225; p = 0.238). Furthermore, the outcome did not differ in patients with more advanced stages of DD.

CONCLUSION

DD is commonly prevalent in patients with HFmrEF, but not associated with long-term prognosis.

Assessing diastolic function using CMR as an alternative to echocardiography: age- and gender-related normal reference values

BACKGROUND

Impaired diastolic function is associated with a variety of diseases such as myocarditis or dilated cardiomyopathy. Currently, echocardiography is the standard method for assessing diastolic function. Recently, it has been postulated that cardiovascular magnetic resonance (CMR) is an at least equivalent or superior alternative to echocardiography. To assess CMR-based age- and gender-dependent diastolic functional normal reference values, pulmonary venous and transmitral blood-flow parameters were examined in heart-healthy test persons.

METHODS AND RESULTS

Flow-sensitive phase-contrast CMR imaging was performed in the right upper pulmonary vein (RUPV) and at the level of the mitral valve (MV) in 183 healthy subjects (age 10-70 years; 97 women, 86 men). The data was distributed as evenly as possible across all groups. Strong age-dependence was observed for PV S/D; r = 0.718, p < 0.001 (Pearson product-moment correlation) and for transmitral MV E/A; ρ = -0.736, p < 0.001 (Spearman's Rho correlation). Moderate age-dependence was found for PV slope D-wave; r = 0.394, p < 0.001. Except for MV slope E-wave (male -292 cm/s2 interquartile range (IQR) {-338; -243} vs. female -319 ± 82 cm/s2; p = 0.047), no gender-related differences were observed. In a subgroup (N = 100), CMR data were compared with echocardiographic data. Strong correlation was found between CMR and echocardiography for PV S/D; r = 0.545, p < 0.001 and MV E/A; ρ = 0.692, p < 0.001.

CONCLUSION

Diastolic functional parameters change with age, while gender-differences are small. CMR and echocardiography showed similar PV S/D and MV E/A ratios, making CMR a promising alternative for assessing diastolic function.

Enhanced aortic stiffness in adolescents with chronic disease is associated with decreased left ventricular global longitudinal strain

Background

The recent Cardiovascular Disease in Adolescents with Chronic Disease (CDACD) study showed enhanced aortic stiffness and wall thickness in adolescents with various chronic disorders. Enhanced aortic stiffness can increase left ventricular (LV) afterload and trigger a cascade of adverse arterioventricular interaction. Here, we investigate the relation between aortic changes and LV function in the CDACD study participants.

Methods

This cross-sectional study included 114 adolescents 12-18 years old with cystic fibrosis (CF, n = 24), corrected coarctation of the aorta (CoA, n = 25), juvenile idiopathic arthritis (JIA, n = 20), obesity (n = 20), and healthy controls (n = 25). Aortic pulse wave velocity (PWV), which reflects aortic stiffness, and aortic wall thickness (AWT) were assessed with cardiovascular magnetic resonance imaging (CMR). Echocardiography was employed to study conventional markers of LV function, as well as LV global longitudinal strain (LVGLS), which is an established (pre)clinical marker of LV dysfunction.

Results

First, aortic PWV and AWT were increased in all chronic disease groups, compared to controls. Second, in adolescents with CoA, JIA, and obesity, echocardiography showed a decreased LVGLS, while LV dimensions and conventional LV function markers were similar to controls. Third, multivariable linear regression identified aortic PWV as the most important determinant of their decreased LVGLS (standardized β -0.522, p < 0.001).

Conclusions

The decreased LVGLS in several adolescent chronic disease groups was associated with enhanced aortic PWV, which might reflect adverse arterioventricular interaction. Whether the decreased LVGLS in the chronic disease groups could negatively impact their long-term cardiovascular outcomes requires further study.

Cardiomyocyte-specific deletion of GCN5L1 reduces lysine acetylation and attenuates diastolic dysfunction in aged mice by improving cardiac fatty acid oxidation

Cardiac mitochondrial dysfunction is a critical contributor to the pathogenesis of aging and many age-related conditions. As such, complete control of mitochondrial function is critical to maintain cardiac efficiency in the aged heart. Lysine acetylation is a reversible post-translational modification shown to regulate several mitochondrial metabolic and biochemical processes. In the present study, we investigated how mitochondrial lysine acetylation regulates fatty acid oxidation (FAO) and cardiac function in the aged heart. We found a significant increase in mitochondrial protein acetylation in the aged heart which correlated with increased level of mitochondrial acetyltransferase-related protein GCN5L1. We showed that acetylation status of several fatty acid and glucose oxidation enzymes (long-chain acyl-coenzyme A dehydrogenase, hydroxyacyl-coA dehydrogenase, and pyruvate dehydrogenase) were significantly up-regulated in aged heart which correlated with decreased enzymatic activities. Using a cardiac-specific GCN5L1 knockout (KO) animal model, we showed that overall acetylation of mitochondrial proteins was decreased in aged KO animals, including FAO proteins which led to improved FAO activity and attenuated cardiac diastolic dysfunction observed in the aged heart. Together, these findings indicate that lysine acetylation regulates FAO in the aged heart which results in improved cardiac diastolic function and this is in part regulated by GCN5L1.

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.

Parameters associated with improvement of systolic function in patients with heart failure

AIMS

Identifying clinical and echocardiographic parameters associated with improvement in systolic function in outpatients with heart failure with reduced ejection fraction (HFrEF) could lead to more targeted treatment improving systolic function and outcome.

METHODS

In a retrospective cohort study, echocardiographic examinations from the first and final visit of 686 patients with HFrEF at the heart failure clinic at Gentofte Hospital were retrieved and analysed. Parameters associated with left ventricular ejection fraction (LVEF) improvement and survival according to LVEF improvement were assessed using linear regression and Cox regression, respectively. Beta-coefficients (β-coef) are standardised. Strain values are absolute.

RESULTS

While undergoing heart failure treatment, 559 (81.5%) patients improved systolic function ( Δ LVEF >0%), with 100 (14.6%) being super responders defined by LVEF improvement >20%. After multivariable adjustment, LVEF improvement was significantly associated with a less impaired global longitudinal strain (β-coef 0.25, p<0.001), higher tricuspid annular plane systolic excursion (β-coef 0.09, p=0.018), smaller left ventricular internal dimension in diastole (β-coef -0.15, p=0.011), lower E-wave/A-wave ratio (β-coef -0.13, p=0.003), higher heart rate (β-coef 0.18, p<0.001) and absence of ischaemic cardiomyopathy (β-coef -0.11, p=0.010) and diabetes (β-coef -0.081, p=0.033) at baseline. Mortality incidence rates differed with LVEF improvement ( Δ LVEF <0% vs Δ LVEF >0%, 8.3 vs 4.3 per 100 person years, p=0.012). Greater improvement in LVEF was associated with significantly lower mortality risk (tertile 1 vs tertile 3, HR 3.23, 95% CI 1.39 to 7.51, p=0.006).

CONCLUSION

In this outpatient HFrEF cohort, most patients improved systolic function. Heart failure aetiology, comorbidities and echocardiographic measures of heart structure and function were significantly, independently associated with future LVEF improvement. Greater LVEF improvement was significantly associated with lower mortality.

Serum anion gap is associated with mortality in intensive care unit patients with diastolic heart failure

Serum anion gap (AG) is closely related to mortality in critically ill patients with several diseases. We aimed to determine the relationship between serum AG levels and 28-day intensive care unit (ICU) mortality in patients with diastolic heart failure (DHF). This cohort study enrolled critically ill patients with DHF from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. Serum AG levels were calculated using the traditional and albumin-adjusted methods. Multivariate Cox proportional hazards regression and restricted cubic spline curves were used to determine the correlation between serum AG levels and 28-day ICU mortality. We used receiver operating characteristic (ROC) curves and area under the curve (AUC) to compare the ability of traditional and albumin-adjusted AG to predict mortality. Overall, 3290 patients were included. Multivariate analysis showed an association of high levels of traditional (hazard ratio [HR], 1.48; 95% confidence interval [CI], 1.1-1.98, p = 0.009) and albumin-adjusted AG (HR, 1.36; 95% CI, 1.02-1.79, p = 0.033) with higher risk of 28-day ICU mortality. Restricted cubic spline curves indicated a linear relationship between AG level and 28-day ICU mortality. Comparison of the ROC curves revealed that albumin-adjusted AG had a greater ability to predict 28-day ICU mortality compared with traditional AG (AUCs of 0.569 [95% CI, 0.536-0.601] and 0.619 [95% CI, 0.588-0.649], respectively). In ICU patients with DHF, higher levels of traditional and albumin-adjusted AG were associated with higher 28-day ICU mortality. Albumin-adjusted AG exhibited greater predictive ability for mortality compared with traditional AG.

Machine learning-based classification of cardiac relaxation impairment using sarcomere length and intracellular calcium transients

Impaired relaxation of cardiomyocytes leads to diastolic dysfunction in the left ventricle. Relaxation velocity is regulated in part by intracellular calcium (Ca2+) cycling, and slower outflux of Ca2+ during diastole translates to reduced relaxation velocity of sarcomeres. Sarcomere length transient and intracellular calcium kinetics are integral parts of characterizing the relaxation behavior of the myocardium. However, a classifier tool that can separate normal cells from cells with impaired relaxation using sarcomere length transient and/or calcium kinetics remains to be developed. In this work, we employed nine different classifiers to classify normal and impaired cells, using ex-vivo measurements of sarcomere kinematics and intracellular calcium kinetics data. The cells were isolated from wild-type mice (referred to as normal) and transgenic mice expressing impaired left ventricular relaxation (referred to as impaired). We utilized sarcomere length transient data with a total of n = 126 cells (n = 60 normal cells and n = 66 impaired cells) and intracellular calcium cycling measurements with a total of n = 116 cells (n = 57 normal cells and n = 59 impaired cells) from normal and impaired cardiomyocytes as inputs to machine learning (ML) models for classification. We trained all ML classifiers with cross-validation method separately using both sets of input features, and compared their performance metrics. The performance of classifiers on test data showed that our soft voting classifier outperformed all other individual classifiers on both sets of input features, with 0.94 and 0.95 area under the receiver operating characteristic curves for sarcomere length transient and calcium transient, respectively, while multilayer perceptron achieved comparable scores of 0.93 and 0.95, respectively. However, the performance of decision tree, and extreme gradient boosting was found to be dependent on the set of input features used for training. Our findings highlight the importance of selecting appropriate input features and classifiers for the accurate classification of normal and impaired cells. Layer-wise relevance propagation (LRP) analysis demonstrated that the time to 50% contraction of the sarcomere had the highest relevance score for sarcomere length transient, whereas time to 50% decay of calcium had the highest relevance score for calcium transient input features. Despite the limited dataset, our study demonstrated satisfactory accuracy, suggesting that the algorithm can be used to classify relaxation behavior in cardiomyocytes when the potential relaxation impairment of the cells is unknown.

Extracellular vesicles improve diastolic function and substructure in normal and high-fat diet models of chronic myocardial ischemia

OBJECTIVE

The burden of mortality and morbidity of cardiovascular disease is in part due to substantial fibrosis accelerated by coexisting risk factors. This study aims to evaluate the effect of extracellular vesicle therapy on diastolic function and myocardial fibrosis in the setting of chronic myocardial ischemia with and without a high-fat diet.

METHODS

Forty male Yorkshire swine were administered a normal or high-fat diet. At 11 weeks of age, they underwent placement of an ameroid constrictor on their left circumflex coronary artery. Both dietary groups then received either intramyocardial injection of vehicle saline as controls or extracellular vesicles as treatment into the ischemic territory (normal diet control, n = 8; high-fat diet controls, n = 11) or extracellular vesicles (normal diet extracellular vesicles, n = 9; high-fat diet extracellular vesicles, n = 12). Five weeks later, hemodynamic parameters, histology, and selected protein expression were evaluated.

RESULTS

Extracellular vesicles reduced end-diastolic pressure volume relationship (P = .002), perivascular collagen density (P = .031), calcium mineralization (P = .026), and cardiomyocyte diameter (P < .0001), and upregulated osteopontin (P = .0046) and mechanistic target of rapamycin (P = .021). An interaction between extracellular vesicles and diet was observed in the vimentin area (P = .044) and fraction of myofibroblast markers to total vimentin (P = .049). Significant changes across diet were found with reductions in muscle fiber area (P = .026), tumor necrosis factor α (P = .0002), NADPH oxidase 2 and 4 (P = .0036, P = .008), superoxide dismutase 1 (P = .034), and phosphorylated glycogen synthase kinase 3β (P = .020).

CONCLUSIONS

Extracellular vesicle therapy improved the myocardium's ability to relax and is likely due to structural improvements at the extracellular matrix and cellular levels.

The predictive value of changes in left atrial volume index for rehospitalization in heart failure with preserved ejection fraction

AIMS

Left atrial volume index (LAVI) is an adequate analysis to predicate the left ventricle (LV) filling pressures, providing a powerful predictive marker of LV diastolic dysfunction. LAVI is a dynamic morphophysiological marker, and whether LAVI changes can predicate clinical outcomes in HF with preserved ejection fraction (HFpEF) is unknown.

METHODS

HFpEF patients were retrospectively studied from the First Affiliated Hospital of Dalian Medical University. Patients were classified into deteriorated, stable and improved groups according to the change in LAVI. Rehospitalization was defined as the main endpoint, the composite outcome of rehospitalization or all-cause death was defined as the secondary endpoint.

RESULTS

A total of 409 patients were included. In this cohort, the percentage of deteriorated, stable, and improved LAVI were 99 (24.2%), 235 (57.4%), and 75 (18.4%), respectively. During the 22 months follow-up period, 168 patients (41.1%) were rehospitalized, 31 patients (7.5%) died and 182 patients (44.5%) experienced a composite outcome. Multivariate Cox regression showed that compared to improved LAVI, those with deteriorated and stable LAVI experienced higher risk of rehospitalization. Logistic regression showed atrial fibrillation (AF) and higher creatinine were independent predictors of deteriorated LAVI, whereas the use of loop diuretics, calcium channel blockers (CCB), and high level of high-density lipoprotein cholesterol (HDL-C) were significantly associated with improved LAVI.

CONCLUSIONS

Change in LAVI provides a powerful and dynamic morphophysiological marker of LV filling status and can be used to evaluate the rehospitalization in HFpEF patients.

Mitochondrial oxidative stress contributes to diastolic dysfunction through impaired mitochondrial dynamics

Diastolic dysfunction (DD) underlies heart failure with preserved ejection fraction (HFpEF), a clinical syndrome associated with aging that is becoming more prevalent. Despite extensive clinical studies, no effective treatment exists for HFpEF. Recent findings suggest that oxidative stress contributes to the pathophysiology of DD, but molecular mechanisms underpinning redox-sensitive cardiac remodeling in DD remain obscure. Using transgenic mice with mitochondria-targeted NOX4 overexpression (Nox4TG618) as a model, we demonstrate that NOX4-dependent mitochondrial oxidative stress induces DD in mice as measured by increased E/E', isovolumic relaxation time, Tau Glantz and reduced dP/dtmin while EF is preserved. In Nox4TG618 mice, fragmentation of cardiomyocyte mitochondria, increased DRP1 phosphorylation, decreased expression of MFN2, and a higher percentage of apoptotic cells in the myocardium are associated with lower ATP-driven and maximal mitochondrial oxygen consumption rates, a decrease in respiratory reserve, and a decrease in citrate synthase and Complex I activities. Transgenic mice have an increased concentration of TGFβ and osteopontin in LV lysates, as well as MCP-1 in plasma, which correlates with a higher percentage of LV myocardial periostin- and ACTA2-positive cells compared with wild-type mice. Accordingly, the levels of ECM as measured by Picrosirius Red staining as well as interstitial deposition of collagen I are elevated in the myocardium of Nox4TG618 mice. The LV tissue of Nox4TG618 mice also exhibited increased ICaL current, calpain 2 expression, and altered/disrupted Z-disc structure. As it pertains to human pathology, similar changes were found in samples of LV from patients with DD. Finally, treatment with GKT137831, a specific NOX1 and NOX4 inhibitor, or overexpression of mCAT attenuated myocardial fibrosis and prevented DD in the Nox4TG618 mice. Together, our results indicate that mitochondrial oxidative stress contributes to DD by causing mitochondrial dysfunction, impaired mitochondrial dynamics, increased synthesis of pro-inflammatory and pro-fibrotic cytokines, activation of fibroblasts, and the accumulation of extracellular matrix, which leads to interstitial fibrosis and passive stiffness of the myocardium. Further, mitochondrial oxidative stress increases cardiomyocyte Ca2+ influx, which worsens CM relaxation and raises the LV filling pressure in conjunction with structural proteolytic damage.

Knockout of TIGAR enhances myocardial phosphofructokinase activity and preserves diastolic function in heart failure

Hypertension is an important risk factor in the pathogenesis of diastolic dysfunction. Growing evidence indicates that glucose metabolism plays an essential role in diastolic dysfunction. TP53-induced glycolysis and apoptosis regulator (TIGAR) has been shown to regulate glucose metabolism and heart failure (HF). In the present study, we investigated the role of TIGAR in diastolic function and cardiac fibrosis during pressure overload (PO)-induced HF. WT mice subjected to transverse aortic constriction (TAC), a commonly used method to induce diastolic dysfunction, exhibited diastolic dysfunction as evidenced by increased E/A ratio and E/E' ratio when compared to its sham controls. This was accompanied by increased cardiac interstitial fibrosis. In contrast, the knockout of TIGAR attenuated PO-induced diastolic dysfunction and interstitial fibrosis. Mechanistically, the levels of glucose transporter Glut-1, Glut-4, and key glycolytic enzyme phosphofructokinase 1 (PFK-1) were significantly elevated in TIGAR KO subjected to TAC as compared to that of WT mice. Knockout of TIGAR significantly increased fructose 2,6-bisphosphate levels and phosphofructokinase activity in mouse hearts. In addition, PO resulted in a significant increase in perivascular fibrosis and endothelial activation in the WT mice, but not in the TIGAR KO mice. Our present study suggests a necessary role of TIGAR-mediated glucose metabolism in PO-induced cardiac fibrosis and diastolic dysfunction.

Aortic wall elasticity and left ventricular function in hypertensive patients with nonsignificant coronary artery disease

PURPOSE

Hypertension is an important cause of nonischemic heart failure. It is important to identify subclinical left ventricular dysfunction in patients with hypertension in an early stage to lower the risk of progression to more severe illness. The aim of our study was to assess the correlation between indices of left ventricular function and aortic stiffness in patients with hypertension.

METHODS

Our study was a case control study of 42 hypertensive and 40 normotensive patients with nonsignificant coronary artery disease. All the patients underwent echocardiography and left ventricular ejection fraction, global longitudinal strain, post systolic index, pulsed Doppler early transmitral peak flow velocity, early diastolic mitral annular velocity (e'), and aortic elasticity measurements were calculated.

RESULTS

The hypertensive patients were older (58.47 ± 9.57 vs. 52.94 ± 10.38 years, p = 0.018) and had a higher body mass index (30.09 ± 5.08 vs. 27.48 ± 4.17 kg/m2, p = 0.013) and E/e' ratio (8.16 ± 1.81 vs. 6.56 ± 1.71, p < 0.001) and a lower e' velocity (8.25 ± 2.28 vs. 9.52 ± 2.34 cm/s, p = 0.015) than normotensives. They also had a lower aortic distensibility (p = 0.008) and a higher aortic stiffness index (p = 0.039) compared with the normotensive group. The hypertensive patients did not show any association between aortic elasticity and stiffness with age or e' velocity despite significant association in normotensives.

CONCLUSION

Hypertension is associated with a high prevalence of diastolic dysfunction, elevated left ventricular filling pressure, and increased arterial stiffness, all of which have significant association with adverse outcomes. The measurements found in the hypertensive patients compared with the normotensive group may be due to several age-independent mechanisms.

Aortic arch calcification: a novel parameter for prediction of masked hypertension

BACKGROUND

Masked hypertension is directly related to increased cardiovascular morbidity and mortality but remains underdiagnosed in clinical practice. The aim of the study was to search the role of aortic arch calcification (AAC) in the diagnosis of masked hypertension.

METHODS AND RESULTS

Among the patients who underwent ambulatory blood pressure monitoring (ABPM) in our clinic, those with office blood pressure (OBP) <140/90 mmHg were included in the study population. According to OBP, they were divided into two groups as normal (<130/85 mmHg) and high normal (130-139/85-89 mmHg) OBP groups. Subjects were also investigated for the presence of masked hypertension with ABPM and searched in masked hypertension and control groups. Masked hypertension was defined as in the latest 2017 ACC/AHA Hypertension guideline and was diagnosed as the daytime BP ≥ 135/85 mmHg and nighttime BP ≥ 120/70 mmHg. AAC was evaluated on direct X-ray telecardiography. Diagnosis of masked hypertension was searched depending on the presence of AAC and OBP measurements as well. A total of 216 volunteers were involved in the study [mean age 45.2 ± 12.2 years; female gender 120 (55.5%)]. One hundred ten volunteers (50.9%) had masked hypertension according to the ABPM. AAC was significantly more common in the masked hypertension group (44.5% vs. 26.4%) (P = 0.005). AAC had a positive predictive value of 79% in those with high normal OBP in the diagnosis of masked hypertension, and also AAC had a negative predictive value of 74% in those with normal OBP.

CONCLUSION

AAC can be used as a reliable diagnostic tool to exclude and predict masked hypertension during office examination.

Differences between diabetic and non-diabetic nephropathy patients in cardiac structure and function at the beginning of hemodialysis and their impact on the prediction of mortality

OBJECTIVES

To characterize differences in cardiac structure and function in hemodialysis (HD) patients with diabetic nephropathy (DN) and in those without using echocardiography and to determine their impact on the prediction of mortality using echocardiographic parameters.

METHODS

Clinical, laboratory, and echocardiographic data were collected from patients commencing HD.

RESULTS

Compared with those without DN, patients with DN had lower peak velocity of the early diastolic wave (e'), larger left atria, and higher peak early diastolic velocity (E)/e' and peak velocity of tricuspid regurgitation (TR). In addition, a larger proportion of DN patients had a combination of left ventricular (LV) diastolic dysfunction, cardiac valve calcification, moderate-to-severe cardiac valve regurgitation (CVR), and at least moderate pericardial effusion (PE). After accounting for age, sex, smoking, hypertension, hemoglobin, and albumin, DN was responsible for e'  < 10 cm/s, E/e' >13 m/s, TR >2.8 m/s, LV diastolic dysfunction, CVR, and PE. LV diastolic dysfunction and E/e' >13 were the most useful predictors of mortality in patients with DN.

CONCLUSIONS

Patients with DN who undergo HD tend to have worse LV diastolic function and are more likely to have heart valve problems. LV diastolic dysfunction and E/e' are predictors of death in DN patients.

Neonatal hyperoxia inhibits proliferation and survival of atrial cardiomyocytes by suppressing fatty acid synthesis

Preterm birth increases the risk for pulmonary hypertension and heart failure in adulthood. Oxygen therapy can damage the immature cardiopulmonary system and may be partially responsible for the cardiovascular disease in adults born preterm. We previously showed that exposing newborn mice to hyperoxia causes pulmonary hypertension by 1 year of age that is preceded by a poorly understood loss of pulmonary vein cardiomyocyte proliferation. We now show that hyperoxia also reduces cardiomyocyte proliferation and survival in the left atrium and causes diastolic heart failure by disrupting its filling of the left ventricle. Transcriptomic profiling showed that neonatal hyperoxia permanently suppressed fatty acid synthase (Fasn), stearoyl-CoA desaturase 1 (Scd1), and other fatty acid synthesis genes in the atria of mice, the HL-1 line of mouse atrial cardiomyocytes, and left atrial tissue explanted from human infants. Suppressing Fasn or Scd1 reduced HL-1 cell proliferation and increased cell death, while overexpressing these genes maintained their expansion in hyperoxia, suggesting that oxygen directly inhibits atrial cardiomyocyte proliferation and survival by repressing Fasn and Scd1. Pharmacologic interventions that restore Fasn, Scd1, and other fatty acid synthesis genes in atrial cardiomyocytes may, thus, provide a way of ameliorating the adverse effects of supplemental oxygen on preterm infants.

Obese and Type 2 Diabetic Youth Have Increased Forward and Backward Wave Reflections

OBJECTIVE

Pulse wave analysis estimates arterial wave reflections relating to left ventricular dysfunction and cardiovascular event risk in adults. Forward and backward waves (Pf and Pb) may improve risk stratification for cardiovascular events. Data in youth are lacking. We hypothesized that a significant difference in wave reflections would be identified in young subjects with adverse cardiovascular risk factors. Approach and Results: Vital signs and labs were obtained in 551 patients aged 10 to 24 years who were lean (L=199), obese (O=173), or had type 2 diabetes (T=179). Wave separation was performed. Differences in cardiovascular risk factors and wave reflections were assessed using ANOVA. General linear models were constructed to elucidate independent predictors of wave reflections. O and T subjects had an adverse cardiovascular risk profile versus L. O and T subjects had higher Pf and Pb versus L (P≤0.05). When adjusted for adiposity and other cardiovascular risk factors, reflection magnitude increased from L to O to T with higher T versus L values (P≤0.05) and near-significant O versus L values (P=0.06). Adiposity and blood pressure were major determinants of wave reflections. Pb influenced log left ventricular mass index, log E/e', and log composite carotid intima-media thickness.

CONCLUSIONS

Adolescents and young adults with obesity and type 2 diabetes have altered forward and backward wave reflections versus lean controls related to adiposity, BP, and insulin levels. These parameters may help risk stratify patients with adverse cardiovascular risk factors.

Relationship between low skeletal muscle mass, sarcopenic obesity and left ventricular diastolic dysfunction in Korean adults

BACKGROUND

Heart failure with preserved ejection fraction is an emerging global health issue attributed to an ageing population. However, the association between low skeletal muscle mass, sarcopenic obesity, and left ventricular diastolic dysfunction remains unclear. In the current study, we aimed to investigate the relationship between low skeletal muscle mass, sarcopenic obesity, and diastolic dysfunction in a large cohort of Korean adults.

METHODS

We conducted a cross-sectional study of 31 258 subjects who underwent health examinations at Samsung Medical Centre's Health Promotion Centre in Seoul, Republic of Korea. Relative skeletal muscle mass was calculated using the skeletal muscle mass index [SMI (%) = appendicular skeletal muscle mass (kg)/body weight (kg) × 100], which was estimated by bioelectrical impedance analysis. Cardiac structure and function were evaluated by echocardiography.

RESULTS

Amongst the 31 258 subjects, 3058 (9.78%) were determined to have diastolic dysfunction. The odds ratio (OR) of diastolic dysfunction was 1.56 [95% confidence interval (CI): 1.31-1.85; p for trend <0.001] for the lowest SMI tertile relative to the highest SMI tertile following multivariable adjustment. Furthermore, the risk of diastolic dysfunction was much higher in the sarcopenic obesity (OR: 1.70, 95% CI: 1.44-1.99), followed by in the obesity-only (OR: 1.40, 95% CI: 1.21-1.62), and sarcopenia-only (OR: 1.32, 95% CI: 1.08-1.61) when compared with the nonobese, nonsarcopenic group. These results remained consistent amongst the elderly (age ≥ 65 years).

CONCLUSIONS

Our findings demonstrate that lower skeletal muscle mass and sarcopenic obesity are strongly associated with diastolic dysfunction in middle-aged and older adults.

Impact of Pulse Wave Velocity and Parameters Reflecting Android Type Fat Distribution on Left Ventricular Diastolic Dysfunction in Patients with Chronic Coronary Syndromes

Background: Left ventricular diastolic dysfunction (LVDD) is caused by a decreased left ventricle relaxation and is associated with an increased risk of symptomatic heart failure (HF) and excessive mortality. Aim: To evaluate the frequency and factors related to LVDD in the population with chronic coronary syndromes (CCS). Methods: 200 patients (mean age 63.18 ± 8.12 years, 75.5% male) with CCS were included. LVDD was diagnosed based on the recent echocardiography guidelines. Results: LVDD was diagnosed in 38.5% of CCS population. From the studied factors, after adjustment for age, sex, and N-terminal pro-brain natriuretic peptide (NT-proBNP), LVDD associated positively with android/gynoid (A/G) fat mass ratio, left ventricular mass index (LVMI), and negatively with Z-score and left ventricular ejection fraction (LVEF). In stepwise backward logistic regression analysis, the strongest factors associated with LVDD were pulse wave velocity value, handgrip strength and waist to hip ratio (WHR). Conclusions: LVDD is common among CCS patients and it is associated with parameters reflecting android type fat distribution regardless of NT-proBNP and high-sensitivity troponin T concentrations. Deterioration in diastolic dysfunction is linked with increased aortic stiffness independently of age and sex. Further studies evaluating the effects of increasing physical fitness and lowering abdominal fat accumulations on LVDD in CCS patients should be considered.

Is Masked Hypertension an underlying Cause of Unexplained Left Ventricle Hypertrophy?

OBJECTIVES

Unexplained left ventricular hypertrophy (ULVH) is defined as increased wall thickness in the absence of conditions that predispose to hypertrophy. The aim of this study was to evaluate the rate of masked hypertension in patient with unexplained left ventricle hypertrophy.

METHOD

A total of 120 consecutive unexplained left ventricle hypertrophy patients without overt hypertension and diabetes and 121 healthy control subjects were included in the study. After a complete medical history and laboratory examination, patients' height, weight, waist circumference heart rate, and office blood pressure were recorded. All subjects underwent ambulatory blood pressure monitoring, and transthoracic echocardiography.

RESULTS

Mean age were similar between patients with ULVH and controls. There was no significant difference in total cholesterol, HDL, LDL cholesterol and triglyceride levels, left ventricle ejection fraction, between the groups. Prevalence of Masked hypertension was significantly higher in patients with ULVH than controls (28.3% vs 6.6%, p < .001). Left ventricular mass index (141.9 ± 16.8 g/cm² vs. 67.3 ± 10.3 g/cm², p < .001) was significantly higher in masked hypertensive patients with ULVH compared to normotensive ULVH and control subjects.

CONCLUSION

In this study, we found high prevalence of masked hypertension in ULVH patients. Patients with ULVH should be screened by ABPM to detect possible masked hypertension.

The Relationship between Tumor Necrosis Factor Alpha and Left Ventricular Diastolic Function

Introduction:

Left ventricular (LV) diastolic dysfunction is a common condition. Tumor necrosis factor (TNF) alpha is an inflammatory cytokine that plays a role in the development of cardiac structural changes leading to LV diastolic dysfunction. The aim of this study was to examine the relationship between serum levels of TNF alpha levels and LV diastolic function.

Methods:

A case–control study that included 40 patients with echocardiographic evidence of LV diastolic dysfunction and 40 healthy controls. Standard transthoracic echocardiography was performed to assess LV and left atrial volumes, systolic and diastolic function according to the current recommendations. Serum TNF alpha levels were assessed using a specific enzyme-linked immunosorbent assay kit.

Results:

Mean serum TNF alpha level was significantly higher in the study group 3.48 ± 1.06 versus 1.22 ± 0.36 pg/ml in the control group, P < 0.001. It was also higher in patients with Grade 2 diastolic dysfunction (n = 16) 3.91 ± 1.21 versus 3.18 ± 0.86 pg/ml in those with Grade 1 diastolic dysfunction (n = 24), P = 0.03. TNF alpha showed a strong correlation with indexed left atrial volume (LAVI) in the study group but not in controls. Mean serum TNF showed a trend toward increase with worsening heart failure symptoms in the form of increased the New York Heart Association functional class.

Conclusion:

Serum TNF alpha level is elevated in patients with LV diastolic dysfunction and is correlated to LAVI in such patients. Patients with Grade 2 diastolic dysfunction have higher serum levels of TNF alpha compared to those with Grade 1 diastolic dysfunction. TNF alpha levels increase with worsening heart failure symptoms.

Left ventricular remodelling in long-term survivors after the arterial switch operation for transposition of the great arteries

Aims

The objective of this study was to quantify imaging markers of myocardial fibrosis and assess myocardial function in long-term transposition of the great arteries survivors after the arterial switch operation (ASO).

Methods and results

Paediatric ASO patients were prospectively studied by cardiac magnetic resonance imaging, including first-pass myocardial perfusion, late gadolinium enhancement, and T1 relaxometry, as well as echocardiography for left ventricular (LV) systolic and diastolic function including strain analysis, with comparison to healthy controls. Thirty ASO patients (mean age 15.4 ± 2.9 years vs. 14.1 ± 2.6 years in 28 controls, P = 0.04) were included. Patients had normal LV ejection fraction (EF) (57 ± 5% vs. 59 ± 5%, P = 0.07), but end-diastolic and end-systolic volumes were increased (104 ± 20 mL/m2 vs. 89 ± 10 mL/m2, P < 0.01 and 46 ± 13 mL/m2 vs. 36 ± 7 mL/m2, P < 0.01, respectively). Longitudinal strain at two-, three-, and four-chamber levels of the LV were lower in ASO patients (-19.0 ± 2.6% vs. -20.9 ± 2.3%, P = 0.006, -17.7 ± 2.0% vs. -19.1 ± 2.4%, P = 0.02, and -18.9 ± 1.9% vs. -20.1 ± 1.7%, P = 0.01, respectively), while circumferential strain was higher at all short-axis levels (-24.6 ± 2.3% vs. -19.3 ± 1.6%, P < 0.001 at the mid-ventricular level). LV native T1 times were higher in ASO patients (1042 ± 27 ms vs. 1011 ± 27 ms, P < 0.01) and correlated with LV mass/volume ratio (R = 0.60, P < 0.001). Myocardial scarring or myocardial perfusion defects were not observed in our cohort.

Conclusion

Children and adolescents after ASO have normal LV systolic function, in line with their overall good clinical health. At a myocardial level however, imaging markers of diffuse myocardial fibrosis are elevated, along with an altered LV contraction pattern. Whether these abnormalities will progress into future clinically significant dysfunction and whether they are harbingers of adverse outcomes remains to be studied.

Age-dependent association of pulse wave velocity with coronary artery disease and myocardial aging in high-risk patients

AIMS

Progressive arterial stiffening, as a marker of arterial aging, may reach a plateau in elderly patients and may thus lose its clinical utility. This phenomenon may be more prominent in high-risk patients. We aimed to investigate if carotid-to-femoral pulse wave velocity (cf-PWV) is related to coronary artery disease (CAD) and diastolic dysfunction in elderly high-risk patients as compared to a control group of younger individuals.

METHODS

One-hundred and ninety-two high-risk stable patients who underwent coronary artery angiography and assessment of cf-PWV were consecutively recruited. Indices of diastolic dysfunction were also measured by echocardiography, including the volume of the left atrium and the ratio of early transmitral peak velocity (E) to the mitral annular early diastolic velocity (E').

RESULTS

Increased cf-PWV was associated with the presence of CAD [odds ratio (OR) 1.34, P = 0.02], number of diseased coronary vessels (OR 1.17, P = 0.029) and CAD severity (P = 0.023) as assessed by Gensini score, in patients less than 65 years old after adjustment for traditional risk factors. Moreover, cf-PWV correlated with E/E' (P = 0.019) and increased the odds by 16% (OR 1.16, P = 0.048) for more severe diastolic dysfunction in patients aged below 65 years old. None of these outcomes correlated with cf-PWV in the elderly.

CONCLUSION

In high cardiovascular risk patients, an age-dependent association of cf-PWV with CAD and diastolic dysfunction was evinced. In contrast to younger patients, these results suggest that measuring arterial stiffness in elderly high-risk patients may lack clinical value.

Left Ventricular Function Before and After Aerobic Exercise Training in Women With Pulmonary Arterial Hypertension

BACKGROUND

Pulmonary arterial hypertension (PAH) is a chronic debilitating illness. The effects of vigorous aerobic exercise training (AET) on heart function in PAH are poorly understood.

METHODS

Eighteen women with PAH (aged 56.2 ± 8.8 yr, body mass index: 28.8 ± 7.3 kg/m) underwent 10 wk of vigorous AET. Cardiac function was observed at rest and peak exercise using bioelectrical impedance cardiography before and after the AET. Cardiac function was observed in a small PAH subset (n = 7) for 10 wk before beginning the AET. A cohort of sedentary women (n = 19) served as healthy controls.

RESULTS

Left ventricular ejection fraction (48 ± 9.2 vs 61.5 ± 13.3%, P = .034) and the systemic vascular resistance index (2258 ± 419.1 vs 2939 ± 962.4 dyn·sec/cm·m, P = .008) were lower at supine rest in the baseline PAH group versus the healthy group, as were peak exercise heart rate (140 ± 13.3 vs 170 ± 13.8 beats/min, P < .001) and systemic vascular resistance index (828 ± 141.1 vs 824 ± 300.9 dyn·sec/cm·m, P = .050) after controlling for age and heart rate. Systemic vascular resistance index measured at peak exercise decreased in the PAH group after AET (828 ± 141.1 vs 766 ± 139.6 dyn·sec/cm·m, P = .020). Left ventricular early diastolic filling ratio worsened in the PAH subset prior to AET (95.9 ± 19.4 vs 76.2 ± 18.9%, P = .043) and remained unchanged after AET.

CONCLUSION

Vigorous AET was not associated with significant declines in left ventricular systolic or diastolic function in women with PAH. Aerobic exercise training may be beneficial for reducing afterload and may preserve left ventricular diastolic function.

Preparticipation Cardiovascular Screening of Student-Athletes with Echocardiography: Ethical, Clinical, Economic, and Legal Considerations

PURPOSE OF REVIEW

To identify whether the use of echocardiography is a viable approach for the screening of athletes for the prevention of sudden cardiac death when considering ethical, clinical, economic, and legal issues.

RECENT FINDINGS

Ethical musings, echocardiographic findings, economic calculations, and legal analysis suggest that echocardiographic screening may reduce sudden cardiac death on the athletic field. Ethical, clinical, economic, and legal considerations suggest echocardiographic screening is a viable option to meet the societal goal to prevent athletic field sudden death.

Imaging technologies for cardiac fiber and heart failure: a review

There has been an increasing interest in studying cardiac fibers in order to improve the current knowledge regarding the mechanical and physiological properties of the heart during heart failure (HF), particularly early HF. Having a thorough understanding of the changes in cardiac fiber orientation may provide new insight into the mechanisms behind the progression of left ventricular (LV) remodeling and HF. We conducted a systematic review on various technologies for imaging cardiac fibers and its link to HF. This review covers literature reports from 1900 to 2017. PubMed and Google Scholar databases were searched using the keywords "cardiac fiber" and "heart failure" or "myofiber" and "heart failure." This review highlights imaging methodologies, including magnetic resonance diffusion tensor imaging (MR-DTI), ultrasound, and other imaging technologies as well as their potential applications in basic and translational research on the development and progression of HF. MR-DTI and ultrasound have been most useful and significant in evaluating cardiac fibers and HF. New imaging technologies that have the ability to measure cardiac fiber orientations and identify structural and functional information of the heart will advance basic research and clinical diagnoses of HF.

Serum Uric Acid is Independently Associated with Diastolic Dysfunction in Apparently Healthy Subjects with Essential Hypertension

OBJECTIVES

Accumulating evidence suggests a direct role of Uric Acid (UA) on Left Ventricular (LV) diastolic function in chronic kidney disease and Heart Failure (HF) patients. Recently, UA has been linked to LV Hypertrophy (LVH) and Diastolic Dysfunction (DD) in women with preserved Ejection Fraction (pEF) but not in corresponding men. We sought to assess if UA could predict indices of DD in hypertensive subjects with pEF independently of gender.

METHOD

We consecutively recruited 382 apparently healthy hypertensive subjects (age: 61.7±10.7, women: 61.3%, median EF: 64%). In 318 patients in sinus rhythm, LV mass-indexed to body surface area-was calculated (LVMI). LVH was set as an LVMI >116g/m2 or 96 g/m2 in men and women, respectively. The ratio of early transmitral peak velocity (E) to the mitral annular early diastolic velocity (Em) was used as an approximation of mean left atrial pressure (E/Em).

RESULTS

UA [median (interquartile range): 5.4(2) mg/dl] independently predicted E/Em (adjusted coefficient: 1.01, p =0.026) while an interaction term between gender and UA was no significant (p=0.684). An ordinal score of DD was calculated taking into account increased E/Em, left atrium dilatation and LVH. Women with increased UA had 254% increased odds (adjusted OR=2.54, p=0.005) to be classified in the upper range of the DD score.

CONCLUSION

In hypertensive subjects without HF, UA is independently associated with the presence of DD in both genders and correlates with its severity in women. Further prospective studies are warranted to evaluate the association of UA with adverse cardiovascular outcomes in high-risk populations such as HF with pEF.

Saxagliptin but Not Sitagliptin Inhibits CaMKII and PKC via DPP9 Inhibition in Cardiomyocytes

Some oral anti-hyperglycemic drugs, including gliptins that inhibit dipeptidyl peptidase 4 (DPP4), have been linked to the increased risk of heart failure (HF) in type-2 diabetic patients. While the cardiovascular safety trial, TECOS, revealed no link between sitagliptin and the risk of HF, a substantial 27% increase in the hospitalization for HF was observed in type-2 diabetic patients treated with saxagliptin within the SAVOR-TIMI 53 trial. A previous in vitro study revealed that saxagliptin impairs the Ca2+/calmodulin-dependent protein kinase II (CaMKII)-phospholamban (PLB)-sarcoplasmic reticulum Ca2+-ATPase 2a axis and protein kinase C (PKC) activity in cardiomyocytes leading to impaired cardiac contractility and electrophysiological function. However, the link between saxagliptin and its target proteins (CaMKII and PKC) remains to be explored. Since DPP8 and DPP9 (but not DPP4) are expressed by cardiomyocytes and saxagliptin is internalized by cardiomyocytes, we investigated whether DPP8/9 contribute to saxagliptin-mediated inhibition of CaMKII and PKC activity. Structural analysis revealed that the DPP4-saxagliptin interaction motif (S630, Y547) for the cyanopyrrolidine group is conserved in DPP8 (S755, Y669) and DPP9 (S730, Y644). Conversely, F357 that facilitates binding of the anchor lock domain of sitagliptin in the S2 extensive subsite of DPP4 is not conserved in DPP8/9. In parallel, unlike saxagliptin, sitagliptin did not affect phosphorylation of CaMKII/PLB or activity of PKC in HL-1 cardiomyocytes. These findings were recapitulated by pharmacological inhibition (TC-E-5007, a DPP8/9 antagonist) and knock-down of DPP9 (but not DPP8). In primary mouse ventricular cardiomyocytes, saxagliptin (but not sitagliptin) impaired Ca2+ transient relaxation and prolonged action potential duration (APD). These results suggest that saxagliptin-DPP9 interaction impairs the CaMKII-PLB and PKC signaling in cardiomyocytes. We reveal a novel and potential role of DPP9 in cardiac signaling. The interaction of saxagliptin with DPP9 may represent an underlying mechanism for the link between saxagliptin and HF. Elucidation of saxagliptin-DPP9 interaction and downstream events may foster a better understanding of the role of gliptins as modulators of cardiac signaling.

Inhibition of prolyl hydroxylases alters cell metabolism and reverses pre-existing diastolic dysfunction in mice

BACKGROUND

Diastolic dysfunction is emerging as a leading cause of heart failure in aging population. Induction of hypoxia tolerance and reprogrammed cell metabolism have emerged as novel therapeutic strategies for the treatment of cardiovascular diseases.

METHODS AND RESULTS

In the present study, we showed that deletion of sirtuin 3 (SIRT3) resulted in a diastolic dysfunction together with a significant increase in the expression of prolyl hydroxylases (PHD) 1 and 2. We further investigated the involvement of PHD in the development of diastolic dysfunction by treating the 12-14 months old mice with a PHD inhibitor, dimethyloxalylglycine (DMOG) for 2 weeks. DMOG treatment increased the expression of hypoxia-inducible factor (HIF)-1α in the endothelium of coronary arteries. This was accompanied by a significant improvement of coronary flow reserve and diastolic function. Inhibition of PHD altered endothelial metabolism by increasing glycolysis and reducing oxygen consumption. Most importantly, treatment with DMOG completely reversed the pre-existing diastolic dysfunction in the endothelial-specific SIRT3 deficient mice.

CONCLUSIONS

Our findings demonstrate that inhibition of PHD and reprogrammed cell metabolism can reverse the pre-existed diastolic dysfunction in SIRT3 deficient mice. Our study provides a potential therapeutic strategy of induction of hypoxia tolerance for patients with diastolic dysfunction associated with coronary microvascular dysfunction, especially in the aging population with reduced SIRT3.

Pathophysiological Mapping of Experimental Heart Failure: Left and Right Ventricular Remodeling in Transverse Aortic Constriction Is Temporally, Kinetically and Structurally Distinct

A growing proportion of heart failure (HF) patients present with impairments in both ventricles. Experimental pressure-overload (i.e., transverse aortic constriction, TAC) induces left ventricle (LV) hypertrophy and failure, as well as right ventricle (RV) dysfunction. However, little is known about the coordinated progression of biventricular dysfunction that occurs in TAC. Here we investigated the time course of systolic and diastolic function in both the LV and RV concurrently to improve our understanding of the chronology of events in TAC. Hemodynamic, histological, and morphometric assessments were obtained from the LV and RV at 2, 4, 9, and 18 weeks post-surgery. Results: Systolic pressures peaked in both ventricles at 4 weeks, thereafter steadily declining in the LV, while remaining elevated in the RV. The LV and RV followed different structural and functional timelines, suggesting the patterns in one ventricle are independent from the opposing ventricle. RV hypertrophy/fibrosis and pulmonary arterial remodeling confirmed a progressive right-sided pathology. We further identified both compensation and decompensation in the LV with persistent concentric hypertrophy in both phases. Finally, diastolic impairments in both ventricles manifested as an intricate progression of multiple parameters that were not in agreement until overt systolic failure was evident. Conclusion: We establish pulmonary hypertension was secondary to LV dysfunction, confirming TAC is a model of type II pulmonary hypertension. This study also challenges some common assumptions in experimental HF (e.g., the relationship between fibrosis and filling pressure) while addressing a knowledge gap with respect to temporality of RV remodeling in pressure-overload.

Evaluation of Modified Look-Locker Inversion Recovery and Arrhythmia-Insensitive Rapid Cardiac T1 Mapping Pulse Sequences in Cardiomyopathy Patients

OBJECTIVE

The aim of this study was to compare the performance of arrhythmia-insensitive rapid (AIR) and modified Look-Locker inversion recovery (MOLLI) T1 mapping in patients with cardiomyopathies.

METHODS

In 58 patients referred for clinical cardiac magnetic resonance imaging at 1.5 T, we compared MOLLI and AIR native and postcontrast T1 measurements. Two readers independently analyzed myocardial and blood T1 values. Agreement between techniques, interreader agreement per technique, and intrascan agreement per technique were evaluated.

RESULTS

The MOLLI and AIR T1 values were strongly correlated (r = 0.98); however, statistically significantly different T1 values were derived (bias 80 milliseconds, pooled data, P < 0.01). Both techniques demonstrated high repeatability (MOLLI, r = 1.00 and coefficient of repeatability [CR] = 72 milliseconds; AIR, r = 0.99 and CR = 184.2 milliseconds) and produced high interreader agreement (MOLLI, r = 1.00 and CR = 51.7 milliseconds; AIR, r = 0.99 and CR = 183.5 milliseconds).

CONCLUSIONS

Arrhythmia-insensitive rapid and MOLLI sequences produced significantly different T1 values in a diverse patient cohort.

Dipeptidyl peptidase-4 independent cardiac dysfunction links saxagliptin to heart failure

Saxagliptin treatment has been associated with increased rate of hospitalization for heart failure in type 2 diabetic patients, though the underlying mechanism(s) remain elusive. To address this, we assessed the effects of saxagliptin on human atrial trabeculae, guinea pig hearts and cardiomyocytes. We found that the primary target of saxagliptin, dipeptidyl peptidase-4, is absent in cardiomyocytes, yet saxagliptin internalized into cardiomyocytes and impaired cardiac contractility via inhibition of the Ca²⁺/calmodulin-dependent protein kinase II-phospholamban-sarcoplasmic reticulum Ca²⁺-ATPase 2a axis and Na⁺-Ca²⁺ exchanger function in Ca²⁺ extrusion. This resulted in reduced sarcoplasmic reticulum Ca²⁺ content, diastolic Ca²⁺ overload, systolic dysfunction and impaired contractile force. Furthermore, saxagliptin reduced protein kinase C-mediated delayed rectifier K⁺ current that prolonged action potential duration and consequently QTc interval. Importantly, saxagliptin aggravated pre-existing cardiac dysfunction induced by ischemia/reperfusion injury. In conclusion, our novel results provide mechanisms for the off-target deleterious effects of saxagliptin on cardiac function and support the outcome of SAVOR-TIMI 53 trial that linked saxagliptin with the risk of heart failure.

New echocardiographic parameters in the diagnosis of heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction (HFpEF) is a serious clinical disease. The pathophysiology of HFpEF is complex, and specific diagnostic criteria have evolved over time. Limited data are available on the quantification of diastolic function using two-dimensional real-time echocardiography, and a simple parameter has not yet been established. The aim of this work is to evaluate new echocardiographic parameters-the diastolic wall strain of the posterior wall (DWS PW) and the vortex formation time (VFT). Echocardiographic data from 111 subjects with exertional dyspnea and normal left ejection fraction (Group A) and 20 healthy volunteers (Group B) were retrospectively evaluated. In addition to the standard parameters used in the diagnosis of HFpEF, DWS PW and VFT were assessed in all patients. HFpEF was diagnosed in 38 patients with dyspnea (Group A1). The remaining 73 patients did not meet the established criteria for a positive diagnosis of HFpEF (Group A2). We discovered that both observed parameters were significantly lower in patients with HFpEF than in other groups. Multivariate analysis revealed that both DWS PW and VFT independently predicted the presence of HFpEF. DWS PW and VFT are simple parameters in the evaluation of diastolic function and may play a potential role as a part of an integrated approach to the assessment of HFpEF.

Cardiac Metabolic Deregulation Induced by the Tyrosine Kinase Receptor Inhibitor Sunitinib is rescued by Endothelin Receptor Antagonism

The growing field of cardio-oncology addresses the side effects of cancer treatment on the cardiovascular system. Here, we explored the cardiotoxicity of the antiangiogenic therapy, sunitinib, in the mouse heart from a diagnostic and therapeutic perspective. We showed that sunitinib induces an anaerobic switch of cellular metabolism within the myocardium which is associated with the development of myocardial fibrosis and reduced left ventricular ejection fraction as demonstrated by echocardiography. The capacity of positron emission tomography with [18F]fluorodeoxyglucose to detect the changes in cardiac metabolism caused by sunitinib was dependent on fasting status and duration of treatment. Pan proteomic analysis in the myocardium showed that sunitinib induced (i) an early metabolic switch with enhanced glycolysis and reduced oxidative phosphorylation, and (ii) a metabolic failure to use glucose as energy substrate, similar to the insulin resistance found in type 2 diabetes. Co-administration of the endothelin receptor antagonist, macitentan, to sunitinib-treated animals prevented both metabolic defects, restored glucose uptake and cardiac function, and prevented myocardial fibrosis. These results support the endothelin system in mediating the cardiotoxic effects of sunitinib and endothelin receptor antagonism as a potential therapeutic approach to prevent cardiotoxicity. Furthermore, metabolic and functional imaging can monitor the cardiotoxic effects and the benefits of endothelin antagonism in a theranostic approach.

Adenosine A2A receptor agonist prevents cardiac remodeling and dysfunction in spontaneously hypertensive male rats after myocardial infarction

Background

This work evaluated the hypothesis that 3,4-methylenedioxybenzoyl-2-thienylhydrazone (LASSBio-294), an agonist of adenosine A_2A receptor, could be beneficial for preventing cardiac dysfunction due to hypertension associated with myocardial infarction (MI).

Methods

Male spontaneously hypertensive rats (SHR) were randomly divided into four groups (six animals per group): sham-operation (SHR-Sham), and myocardial infarction rats (SHR-MI) were treated orally either with vehicle or LASSBio-294 (10 and 20 mg.kg⁻¹.d⁻¹) for 4 weeks. Echocardiography and in vivo hemodynamic parameters measured left ventricle (LV) structure and function. Exercise tolerance was evaluated using a treadmill test. Cardiac remodeling was accessed by LV collagen deposition and tumor necrosis factor α expression.

Results

Early mitral inflow velocity was significantly reduced in the SHR-MI group, and there was significant recovery in a dose-dependent manner after treatment with LASSBio-294. Exercise intolerance observed in the SHR-MI group was prevented by 10 mg.kg⁻¹.d⁻¹ of LASS-Bio-294, and exercise tolerance exceeded that of the SHR-Sham group at 20 mg.kg⁻¹.d⁻¹. LV end-diastolic pressure increased after MI, and this was prevented by 10 and 20 mg.kg⁻¹.d⁻¹ of LASSBio-294. Sarcoplasmic reticulum Ca²⁺ ATPase levels were restored in a dose-dependent manner after treatment with LASSBio-294. Fibrosis and inflammatory processes were also counteracted by LASSBio-294, with reductions in LV collagen deposition and tumor necrosis factor α expression.

Conclusion

In summary, oral administration of LASSBio-294 after MI in a dose-dependent manner prevented the development of cardiac dysfunction, demonstrating this compound’s potential as an alternative treatment for heart failure in the setting of ischemic heart disease with superimposed chronic hypertension.

The impact of diabetes on left ventricular diastolic function in patients with arterial hypertension

OBJECTIVE:

The aim of this study is to analyse the impact of diabetes mellitus on the left ventricular diastolic function in patients with arterial hypertension.

METHODS:

Between July 2007 and July 2008, we enrolled patients aged ≥40 years who had hypertension with or without type 2 diabetes mellitus and unknown history of coronary artery disease who applied to 7.–8. internal medicine polyclinics of Goztepe Education and Training Hospital. Transthoracic echocardiography was used to assess the diastolic function. If patients with positive treadmill exercise test and/or EF ≤%50 in transthoracic echocardiography were excluded from the study. A total of 110 patients (males, n=42 38.2%, and females, n=68; 61.8%) with a mean age of 60.78 (±10.627) years were included in the study. For statistical analysis, SPSS 12.0 program and for the comparison of data chi-square test was used.

RESULTS:

Diastolic dysfunction was significantly more prevalent in diabetes (81.25%) than those without diabetes group (62.9%) (p<0.05). In men, 35.9% in the DM(+) group and 41.1% in the DM(-) group had diastolic dysfunction. In women, 64.1% in the DM(+) group and 58.29% in the DM(-) group had diastolic dysfunction. In the evaluation based on gender, the difference male and female patients was not significant (p>0.05).

CONCLUSION:

Diabetes in association with hypertension has a negative effect on left ventricular diastolic function. This effect appears similar in men and women.

Optical metrics of the extracellular matrix predict compositional and mechanical changes after myocardial infarction

Understanding the organization and mechanical function of the extracellular matrix (ECM) is critical for the development of therapeutic strategies that regulate wound healing following disease or injury. However, these relationships are challenging to elucidate during remodeling following myocardial infarction (MI) due to rapid changes in cellularity and an inability to characterize both ECM microstructure and function non-destructively. In this study, we overcome those challenges through whole organ decellularization and non-linear optical microscopy to directly relate the microstructure and mechanical properties of myocardial ECM. We non-destructively quantify collagen organization, content, and cross-linking within decellularized healthy and infarcted myocardium using second harmonic generation (SHG) and two photon excited autofluorescence. Tensile mechanical testing and compositional analysis reveal that the cumulative SHG intensity within each image volume and the average collagen autofluorescence are significantly correlated with collagen content and elastic modulus of the ECM, respectively. Compared to healthy ECM, infarcted tissues demonstrate a significant increase in collagen content and fiber alignment, and a decrease in cross-linking and elastic modulus. These findings indicate that cross-linking plays a key role in stiffness at the collagen fiber level following infarction, and highlight how this non-destructive approach to assessing remodeling can be used to understand ECM structure-function relationships.

Automated Three-Dimensional Reconstruction of the Left Ventricle From Multiple-Axis Echocardiography

Two-dimensional echocardiography (echo) is the method of choice for noninvasive evaluation of the left ventricle (LV) function owing to its low cost, fast acquisition time, and high temporal resolution. However, it only provides the LV boundaries in discrete 2D planes, and the 3D LV geometry needs to be reconstructed from those planes to quantify LV wall motion, acceleration, and strain, or to carry out flow simulations. An automated method is developed for the reconstruction of the 3D LV endocardial surface using echo from a few standard cross sections, in contrast with the previous work that has used a series of 2D scans in a linear or rotational manner for 3D reconstruction. The concept is based on a generalized approach so that the number or type (long-axis (LA) or short-axis (SA)) of sectional data is not constrained. The location of the cross sections is optimized to minimize the difference between the reconstructed and measured cross sections, and the reconstructed LV surface is meshed in a standard format. Temporal smoothing is implemented to smooth the motion of the LV and the flow rate. This software tool can be used with existing clinical 2D echo systems to reconstruct the 3D LV geometry and motion to quantify the regional akinesis/dyskinesis, 3D strain, acceleration, and velocities, or to be used in ventricular flow simulations.

Cardiovascular magnetic resonance evaluation of left ventricular peak filling rate using steady-state free precession and phase contrast sequences

BACKGROUND

We investigated a practical method to measure peak filling rate (PFR) as an indicator of diastolic function of the left ventricle. Ten adult volunteers underwent cine MR imaging using steady-state free precession (SSFP) and phase contrast (PC) sequences to measure PFR. Two PC image sets were acquired at the mitral valve orifice, and PFR was determined from the set with high true temporal resolution (temporal PC method) or with high spatial resolution (spatial PC method). SSFP images covering the left ventricle were acquired, and a time-volume curve was generated around the peak filling phase. PFR was determined using parabolic curve fitting on the first-derivative curve of the LV time-volume curve.

FINDINGS

PFR values estimated by the PC methods correlated well with those estimated by the SSFP method, despite apparent underestimation. The underestimation was smaller for the temporal PC method (12 %) than for the spatial PC method (28 %). Intra- and inter-observer repeatabilities were better for the PC methods than for the SSFP method.

CONCLUSIONS

PFR measurement by PC imaging with high true temporal resolution is convenient and offers excellent repeatability and acceptable accuracy, indicating suitability for clinical use.

Green tea extract catechin improves internal cardiac muscle relaxation in RCM mice

BACKGROUND

Diastolic dysfunction refers to an impaired relaxation and an abnormality in a heart's filling during diastole while left ventricular systolic function is preserved. Diastolic dysfunction is commonly observed in patients with primary hypertension, diabetes and cardiomyopathies such as hypertrophic cardiomyopathy or restrictive cardiomyopathy. We have generated a restrictive cardiomyopathy (RCM) mouse model with troponin mutations in the heart to mimic the human RCM patients carrying the same mutations.

RESULTS

In the present study, we have investigated the ventricular muscle internal dynamics and pressure developed during systole and diastole by inserting a micro-catheter into the left ventricle of the RCM mice with or without treatment of desensitizer green tea extracts catechins. Our results demonstrate that green tea catechin is able to correct diastolic dysfunction in RCM mainly by improving ventricular compliance and reducing the internal muscle rigidity caused by myofibril hypersensitivity to Ca(2+).

CONCLUSION

Green tea extract catechin is effective in correcting diastolic dysfunction and improving ventricular muscle intrinsic compliance in RCM caused by troponin mutations.

Diastolic dysfunction and cardiac troponin I decrease in aging hearts

Cardiac tropnoin I (cTnI) plays a critical role in the regulation of diastolic function, and its low expression may result in cardiac diastolic dysfunction, which is the most common form of cardiovascular disorders in older adults. In this study, cTnI expression levels were determined in mice at various ages and cardiac function was measured and compared between young adult mice (3 and 10 months) and older mice (18 months). The data indicated that the cTnI levels reached a peak high in young adult hearts (3 months), but decreased in older hearts (18 months). Furthermore, the older hearts showed a significant diastolic dysfunction observed by P-V loop and echocardiography measurements. To further define the mechanism underlying the cTnI decrease in aging hearts, we tested DNA methylation and histone acetylation modifications of cTnI gene. We found that acetylation of histone near the promoter region of cTnI gene played an important role in regulation of cTnI expression in the heart at different ages. Our study indicates that epigenetic modification caused cTnI expression decrease is one of the possible causes that result in a reduced cTnI level and diastolic dysfunction in the older hearts.