E/e' ratio and left atrial area are predictors of atrial fibrillation in patients with hypertrophic cardiomyopathy

The correlation between Fischer's ratio and the risk of cardiac dysfunction in heart failure patients

BACKGROUNDS

Due to the high mortality and hospitalization rate in chronic heart failure (HF), it is of great significance to study myocardial nutrition conditions. Amino acids (AAs) are essential nutrient metabolites for cell development and survival. This study aims to investigate the associations and prognostic value of plasma branched-chain amino acid/aromatic amino acid ratio (Fischer's ratio, FR) in patients with left ventricular ejection fraction (LVEF) ≤ 50%.

METHODS

The value of serum AAs was obtained from 441 cardiovascular patients by liquid chromatography-tandem, including 213 HF patients [all LVEF ≤ 50%, E/e'>14 (n = 101) and E/e'≤14 (n = 112)], and 228 controls without HF [(excluding HF with preserved ejection fraction (EF)]. Two-dimensional echocardiography and Doppler flow imaging determined LVEF and the ratio of early diastolic mitral inflow to mitral annular tissue velocities (E/e'). The abnormal LVEF (≤ 50%) refers to the definition of HF with reduced, mildly reduced, or improved EF. The logistic regression analysis was conducted to measure the FR index and the risk of cardiac dysfunction, and further confirmed by receiver-operating characteristic curves (ROC curve) analysis. In the prospective study, the 188 HF patients were followed up for a mean year (11.74 ± 1.44 months). The event-free HF endpoint or HF readmission was determined by Kaplan-Meier curves, and differences were assessed using log-rank tests, respectively. Cox regression analysis was used to further assess the prognostic value of FR in HF.

RESULTS

FR index decreased gradually along with the control group, HF with E/e'≤14 group, and HF with E/e'>14 group (3.73 ± 1.20 vs. 3.45 ± 0.94 vs. 3.18 ± 0.83, respectively, P < 0.001). Low FR index was associated with HF after full adjustment in all patients [odds ratio (OR): 2.072; 95% confidence interval (CI): 1.546-2.776; P < 0.001]. Meanwhile, low FR index was the independent risk factor for E/e'>14 in HF patients (OR:1.659; 95% CI:1.125-2.446; P = 0.011). The area under the ROC curve for predicting abnormal E/e' was 0.762 (sensitivity 75.51%, specificity 65.05%) by multivariate logistic regression. Furthermore, the decreased FR values indicated poor HF endpoint or HF readmission in HF patients (all Log-rank P < 0.01). The Cox regression analysis showed that low FR tertiles remained correlated to the risk of HF endpoint [hazard ratio (HR): 1.949; 95% CI: 1.006-3.778; P = 0.048].

CONCLUSIONS

In all patients, low FR confers an increased risk for predicting HF. Decreased FR levels could also indicate increased left ventricular (LV) filling pressure in HF. In addition, a lower FR value was associated with higher HF endpoint events. Thus, FR can be a valuable indicator of heart function.

Left atrial size modify the association between uric acid and atrial fibrillation in patients with coronary artery disease

BACKGROUND AND AIMS

The potential influence of left atrial size on the relationship between uric acid and atrial fibrillation has not been fully investigated. This study aims to evaluate the interaction effect of left atrial size on the association between uric acid and atrial fibrillation in patients with coronary artery disease.

METHODS AND RESULTS

This retrospective cohort study, conducted from January 2018 to October 2022, included 2004 patients undergoing Drug-Eluting Stent implantation for coronary artery disease. Utilizing logistic regression models with the product of left atrial enlargement (LAE) and uric acid, interaction effects were assessed. Among the participants, 383 had LAE, and 159 experienced atrial fibrillation. After adjusting for covariates, continuous uric acid levels were associated with an increased risk of atrial fibrillation in patients without LAE (OR:1.631, 95% CI: 1.284-2.072), but not in those with LAE (OR:1.069, 95% CI: 0.848-1.348). A significant interaction of uric acid levels was observed between groups with and without LAE (p = 0.046). Restricted cubic spline curves indicated a J-shaped relationship between uric acid and atrial fibrillation in the absence of LAE. However, the association between uric acid levels and atrial fibrillation in the LAE group remained unchanged with increasing uric acid levels.

CONCLUSION

The study suggested that left atrial size modified the association between uric acid and atrial fibrillation in patients with coronary artery disease. Uric acid serves as a potential biomarker for atrial fibrillation risk, especially in individuals without LAE.

Myosin Inhibition and Left Ventricular Diastolic Function in Patients With Obstructive Hypertrophic Cardiomyopathy Referred for Septal Reduction Therapy: Insights From the VALOR-HCM Study

BACKGROUND

In the randomized phase 3 VALOR-HCM study (A Study to Evaluate Mavacamten in Adults With Symptomatic Obstructive Hypertrophic Cardiomyopathy Who Are Eligible for Septal Reduction Therapy) of patients with obstructive hypertrophic cardiomyopathy, mavacamten reduced the need for septal reduction therapy. Because mavacamten improves ventricular compliance, this sub-study examined the effects of treatment with this cardiac myosin inhibitor on diastolic function.

METHODS

Symptomatic obstructive hypertrophic cardiomyopathy patients on maximally tolerated medical therapy referred for septal reduction therapy were randomized 1:1 to mavacamten or placebo. At baseline and week 16, a resting and stress echocardiogram was performed with interpretation by a core laboratory. In this exploratory substudy, the principal end point was the change in parameters used to define the grade of diastolic function in patients treated with mavacamten and placebo. A related objective was to assess the proportion of patients with an improvement in diastolic function grade. A secondary aim was to assess for correlation between diastolic function parameters and the secondary end points from VALOR-HCM: New York Heart Association class, quality of life, and cardiac biomarkers.

RESULTS

Diastolic dysfunction grade was evaluable in 98 patients at baseline and week 16. Among patients treated with mavacamten, 29.4% (15 of 51) demonstrated improvement in diastolic function grade compared with 12.8% (6 of 47) patients with placebo (P=0.05). Average E/e' ratio decreased significantly in patients treated with mavacamten (-3.4±5.3) compared with placebo (0.57±3.5; P<0.001). Indexed left atrial volumes (mL/m²) also decreased significantly in patients who received mavacamten (-5.2±7.8) compared with placebo (-0.51±8.1; P=0.005). After adjustment for change in left ventricular outflow tract gradient and mitral regurgitation, mavacamten was significantly associated with a decrease in average E/e' ratio and indexed left atrial volumes. Change in average E/e' ratio was significantly correlated with the secondary end points from VALOR-HCM.

CONCLUSIONS

In this exploratory substudy, after 16 weeks of therapy, mavacamten improved diastolic function, and this change correlated with improvement in clinical and biomarker end points.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT04349072.

Putative protective effects of sodium-glucose cotransporter 2 inhibitors on atrial fibrillation through risk factor modulation and off-target actions: potential mechanisms and future directions

Atrial fibrillation, the most common cardiac arrhythmia, results in substantial morbidity and mortality related to its increased risks of stroke, heart failure, and impaired cognitive function. The incidence and prevalence of atrial fibrillation in the general population is rising, making atrial fibrillation treatment and management of its risk factors highly relevant clinical targets. One well-studied risk factor for the development of atrial fibrillation is diabetes mellitus. Inhibitors of sodium-glucose cotransporter 2 (SGLT2), common medications used to treat diabetes mellitus, have been observed to decrease the incidence of atrial fibrillation. This review discusses the SGLT2 and its role in glucose homeostasis, molecules inhibiting the transporter, possible physiological mechanisms responsible for the decreased incident atrial fibrillation in patients treated with SGLT2 inhibitors and proposes mechanistic studies to further our understanding of the biological processes involved.

The Impact of Mavacamten on the Pathophysiology of Hypertrophic Cardiomyopathy: A Narrative Review

Hypertrophic cardiomyopathy (HCM) is a chronic, progressive disease of the cardiomyocyte with a diverse and heterogeneous clinical presentation and course. This diversity and heterogeneity have added to the complexity of modeling the pathophysiological pathways that contribute to the disease burden. The development of novel therapeutic approaches targeting precise mechanisms within the underlying biology of HCM provides a tool to model and test these pathways. Here, we integrate the results of clinical observations with mavacamten, an allosteric, selective, and reversible inhibitor of cardiac myosin, the motor unit of the sarcomere, to develop an integrated pathophysiological pathway model of HCM, confirming the key role of excess sarcomeric activity. This model may serve as a foundation to understand the role of HCM pathophysiological pathways in the clinical presentation of the disease, and how a targeted therapeutic intervention capable of normalizing sarcomeric activity and repopulating low-energy utilization states may reduce the impact of these pathways in HCM and potentially related disease states.

Effect of Mavacamten on Echocardiographic Features in Symptomatic Patients With Obstructive Hypertrophic Cardiomyopathy

BACKGROUND

EXPLORER-HCM (Clinical Study to Evaluate Mavacamten [MYK-461] in Adults With Symptomatic Obstructive Hypertrophic Cardiomyopathy) demonstrated that mavacamten, a cardiac myosin inhibitor, improves symptoms, exercise capacity, and left ventricular outflow tract (LVOT) obstruction in patients with obstructive hypertrophic cardiomyopathy (oHCM).

OBJECTIVES

The purpose of this study was to evaluate mavacamten's effect on measures of cardiac structure and function and its association with changes in other clinical measures.

METHODS

Key echocardiographic parameters from serial echocardiograms over 30 weeks from 251 symptomatic oHCM patients (mavacamten [n = 123], placebo [n = 128]) were assessed in a core laboratory.

RESULTS

More patients on mavacamten (80.9%; n = 76 of 94) vs placebo (34.0%; n = 33 of 97) showed complete resolution of mitral valve systolic anterior motion after 30 weeks (difference, 46.8%; P < 0.0001). Mavacamten also improved measures of diastolic function vs placebo, including left atrial volume index (LAVI) (mean ± SD baseline: 40 ± 12 mL/m² vs 41 ± 14 mL/m²; mean change from baseline of -7.5 mL/m² [95% CI: -9.0 to -6.1 mL/m²] vs -0.09 mL/m² [95% CI: -1.6 to 1.5 mL/m²]; P < 0.0001) and lateral E/e' (baseline, 15 ± 6 vs 15 ± 8; change of -3.8 [95% CI: -4.7 to -2.8] vs 0.04 [95% CI: -0.9 to 1.0]; P < 0.0001). Among mavacamten-treated patients, improvement in resting, Valsalva, and post-exercise LVOT gradients, LAVI, and lateral E/e' was associated with reduction in N-terminal pro-B-type natriuretic peptide (P ≤ 0.03 for all). Reduction in LAVI was associated with improved peak exercise oxygen consumption (P = 0.04).

CONCLUSIONS

Mavacamten significantly improved measures of left ventricular diastolic function and systolic anterior motion. Improvement in LVOT obstruction, LAVI, and E/e' was associated with reduction in a biomarker of myocardial wall stress (N-terminal pro-B-type natriuretic peptide). These findings demonstrate improvement in important markers of the pathophysiology of oHCM with mavacamten. (Clinical Study to Evaluate Mavacamten [MYK-461] in Adults With Symptomatic Obstructive Hypertrophic Cardiomyopathy; NCT03470545).

Strain Analysis of Left Ventricular Function in the Association of Hypertrophic Cardiomyopathy and Systemic Arterial Hypertension

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is the most common heart disease of genetic origin in the world population, with a prevalence of at least 1/500. The association with systemic arterial hypertension (SAH) is not uncommon, as it affects approximately 25% of the world population. Most studies aim at the differential diagnosis between these diseases, but little is known about the magnitude of this association.

OBJECTIVE

To compare left ventricular global longitudinal strain (GLS) in HCM patients with and without associated SAH.

METHODS

Retrospective cross-sectional study that included 45 patients with HCM and preserved ejection fraction, with diagnosis confirmed by magnetic resonance imaging, including 14 hypertensive patients. Transthoracic echocardiography was performed, with emphasis on left ventricular myocardial strain analysis using GLS. In this study, p < 0.05 was considered statistically significant.

RESULTS

Left ventricular strain was significantly lower in hypertensive individuals compared to normotensive individuals (-10.29 ± 2.46 vs. -12.35% ± 3.55%, p = 0.0303), indicating greater impairment of ventricular function in that group. Mean age was also significantly higher in hypertensive patients (56.1 ± 13.9 vs. 40.2 ± 12.7 years, p = 0.0001). Diastolic dysfunction was better characterized in hypertensive patients (p = 0.0242).

CONCLUSION

Myocardial strain was significantly lower in the group of patients with HCM and SAH, suggesting greater impairment of ventricular function. This finding may be related to a worse prognosis with early evolution to heart failure. Prospective studies are required to confirm this hypothesis.