Gender- and age-related differences in distinct phenotypes of hypertrophic cardiomyopathy-associated mutation MYBPC3-E334K

Hypertrophic cardiomyopathy in MYBPC3 carriers in aging

Hypertrophic cardiomyopathy (HCM) is characterized by abnormal thickening of the myocardium, leading to arrhythmias, heart failure, and elevated risk of sudden cardiac death, particularly among the young. This inherited disease is predominantly caused by mutations in sarcomeric genes, among which those in the cardiac myosin binding protein-C3 (MYBPC3) gene are major contributors. HCM associated with MYBPC3 mutations usually presents in the elderly and ranges from asymptomatic to symptomatic forms, affecting numerous cardiac functions and presenting significant health risks with a spectrum of clinical manifestations. Regulation of MYBPC3 expression involves various transcriptional and translational mechanisms, yet the destiny of mutant MYBPC3 mRNA and protein in late-onset HCM remains unclear. Pathogenesis related to MYBPC3 mutations includes nonsense-mediated decay, alternative splicing, and ubiquitin-proteasome system events, leading to allelic imbalance and haploinsufficiency. Aging further exacerbates the severity of HCM in carriers of MYBPC3 mutations. Advancements in high-throughput omics techniques have identified crucial molecular events and regulatory disruptions in cardiomyocytes expressing MYBPC3 variants. This review assesses the pathogenic mechanisms that promote late-onset HCM through the lens of transcriptional, post-transcriptional, and post-translational modulation of MYBPC3, underscoring its significance in HCM across carriers. The review also evaluates the influence of aging on these processes and MYBPC3 levels during HCM pathogenesis in the elderly. While pinpointing targets for novel medical interventions to conserve cardiac function remains challenging, the emergence of personalized omics offers promising avenues for future HCM treatments, particularly for late-onset cases.

Effects of sex on clinical outcomes of hypertrophic cardiomyopathy in Singapore

Introduction

Despite the growing recognition that sex can affect the presentation and outcomes in hypertrophic cardiomyopathy (HCM), this relationship is understudied in Asians. Therefore, we aimed to explore sex differences in Asian patients with HCM.

Method

A total of 295 consecutive patients diagnosed with HCM were recruited from a tertiary cardiology centre from 2010 to 2017 over a mean of 3.9±2.7 years. We evaluated the effects of sex on the outcomes of HCM in Asian patients.

Results

HCM patients were more commonly men (72%). Women were older and had more comorbidities, including hypertension and atrial fibrillation. On transthoracic echocardiography, the indexed left ventricular end-systolic and end-diastolic volumes were similar, but more women had more-than-moderate mitral regurgitation and had a smaller left ventricular outflow tract (LVOT). Women more commonly had findings of obstructive physiology with significant LVOT obstruction, defined as >30 mmHg at rest. The use of implantable cardioverter defibrillators was similar across sexes. On multivariable analysis, women were found to be more likely to develop progressive heart failure requiring admission (hazard ratio [HR] 2.10, 95% confidence interval [CI] 1.05-4.71, P=0.021) but had a lower rate of all-cause mortality (HR 0.36, 95% CI 0.19-0.70, P=0.003).

Conclusion

Women diagnosed with HCM were older, had more comorbidities and were more likely to develop heart failure while men had a higher risk of all-cause mortality.

Gender disparities in alcohol septal ablation for hypertrophic obstructive cardiomyopathy

OBJECTIVE

Alcohol septal ablation (ASA) improves symptoms in hypertrophic obstructive cardiomyopathy (HOCM). We conducted a large retrospective analysis investigating gender effects on outcome after ASA.

METHODS AND RESULTS

1367 ASAs between 2002 and 2020 were analysed. Women (47.2%) were older (66.0 years (IQR 55.0-74.0) vs 54.0 years (IQR 45.0-62.0); p<0.0001) with more severe symptoms. The interventricular septal diameter (IVSD) was higher in men (21.0 mm (IQR 19.0-24.0) vs 20.0 mm (IQR 18.0-23.0); p<0.0001) but the IVSD indexed to body surface area was higher in women (10.9 mm/m² (IQR 9.7-12.7) vs 10.2 mm/m² (IQR 9.0-11.7); p<0.0001). Women had lower exercise-induced left ventricular outflow tract gradients (LVOTG) 1-4 days after ASA (55.0 mm Hg (IQR 30.0-109.0) vs 71.0 mm Hg (IQR 37.0-115.0); p=0.0006). There was a trend for lower resting LVOTG 1-4 days after ASA (20.0 mm Hg (IQR 12.0-37.5) vs 22.0 mm Hg (IQR 13.0-40.0); p=0.0062) and lower exercise-induced LVOTG after 6 months in women (34.0 mm Hg (IQR 21.0-70.0) vs 43.5 mm Hg (IQR 25.0-74.8); p=0.0072), but this was not statistically significant after Bonferroni correction. More women developed atrioventricular (AV) block (20.3% vs 13.3%; p=0.0005) and required a pacemaker (17.4% vs 10.4%; p=0.0002) but not a cardioverter defibrillator (9.0% vs 11.6% in men; p=n .s.). However, in multivariable regression models, there was no evidence that sex independently influenced LVOTG and the occurrence of AV block.

CONCLUSION

Female patients with HOCM were older and had more advanced disease at the time of ASA. Women had superior short-term haemodynamic response to ASA but more often developed AV block after ASA. These results are important to consider for sex-specific counselling before ASA.