Hypertrophic Cardiomyopathy: Current Treatment and Future Options

Nexilin mutations, a cause of chronic heart failure: A state-of-the-art review starting from a clinical case

Heart failure (HF) is a medical condition associated with high morbidity and mortality, despite ongoing advances in diagnosis and treatment. Among the various causes of HF, cardiomyopathies are particularly significant and must be thoroughly diagnosed and characterized from the outset. In this review, we aim to present a brief overview of cardiomyopathies as a driver of HF, with a specific focus on the genetic causes, particularly nexilin (NEXN) cardiomyopathy, illustrated by a clinical case. The case involves a 63-year-old male who presented with HF symptoms at moderate exertion. Six months prior, he had been asymptomatic, and a routine transthoracic echocardiography had shown a preserved left ventricular ejection fraction (LVEF). However, during the current evaluation, transthoracic echocardiography revealed a dilated left ventricle with a severely reduced LVEF of 30%. Subsequent coronary angiography ruled out ischemic heart disease, while cardiac magnetic resonance imaging indicated a non-inflammatory, non-infiltrative dilated cardiomyopathy with extensive LV fibrosis. Genetic testing identified a heterozygous in-frame deletion variant in the NEXN gene [c.1949_1951del, p.(Gly650del)], classified as likely pathogenic. State-of-the-art HF treatment was initiated, including cardiac resynchronization therapy with defibrillator support. Following treatment, the patient's symptoms resolved, and LVEF improved to 42%. Interestingly, this patient experienced the onset of symptoms and left ventricular dysfunction within just six months, a much faster progression compared to previously documented cases where the G650del NEXN variant is typically linked to a more gradual development of dilated cardiomyopathy. Current literature offers limited data on patients with NEXN mutations, and the connection between this gene and both dilated and hypertrophic cardiomyopathies remains an area of active research.

Hypertension and its association to phenotype on left ventricular function in hypertrophic cardiomyopathy patients assessed by cardiovascular magnetic resonance imaging

AIM

The impact of hypertension (HT) on phenotypic expression in individuals with hypertrophic cardiomyopathy (HCM) is unclear.

MATERIALS AND METHODS

Thirty-six HCM individuals without HT, 27 HCM with HT, and 20 age- and sex-matched healthy controls who underwent cardiovascular magnetic resonance imaging (CMR) to evaluate left ventricular (LV) function and strain were enrolled. Three groups' LV function and strain were compared. We also investigated whether HT was associated with reduced LV strain in HCM patients using univariate and multivariate linear regression analyses.

RESULTS

HCM (with/without HT) patients had higher LV mass and LV mass index than the normal controls group. Furthermore, global radial strain, global circumferential strain (GCS), global longitudinal strain, global peak systolic strain rate of radial, and global peak diastolic strain rate of radial were significantly lower in HCM patients with HT, intermediate in HCM patients without HT, and greater in the normal controls (all, P<0.05). Worse GCS was observed in HCM patients with HT than those without HT (P<0.05). Multivariable linear regression analysis showed that HT was independently associated with impaired LV ejection fraction and reduced strain (all P<0.05).

CONCLUSION

The presence of HT was associated with an adverse phenotype, including worse ejection fraction and reduced strains in HCM patients. In addition, management of HT and its effect on the clinical outcomes in HCM patients needs to be studied.

Sex Disparities in the Use and Outcomes of Septal Reduction Therapies for Obstructive Hypertrophic Cardiomyopathy

Background

Data are limited that examine potential sex-based disparities in the utilization and complications of septal reduction therapy (SRT) in patients with obstructive hypertrophic cardiomyopathy. Our aim was to assess the use and in-hospital outcomes of SRT, according to sex. We performed a retrospective cohort study using the 2017-2019 National Inpatient Sample database. Adult patients with obstructive hypertrophic cardiomyopathy were identified.

Methods

We assessed the use of SRT (surgical septal myectomy and alcohol septal ablation), according to sex. In those who underwent SRT, rates of in-hospital mortality, pacemaker implantation, implantable cardioverter defibrillator (ICD) implantation, ischemic stroke, major bleeding, and pericardial complication were assessed. All outcomes were compared between groups using inverse probability of treatment weighting (IPTW), adjusting for demographics, comorbidity burden, and hospital characteristics.

Results

In total, 72,680 weighted hospitalizations (median age: 67 years [range: 57-77]; 61% female patients) were included, and only 5.9% of patients underwent SRT. After IPTW adjustment, female patients were more likely to undergo SRT (adjusted risk ratio [aRR] 1.18, 95% confidence interval [95% CI] 1.03-1.36) and alcohol septal ablation (aRR 1.38, 95% CI 1.04-1.83). Likewise, female patients received pacemaker implantation more often (aRR 1.96, 95% CI 1.10-3.50) and ICD implantation (aRR 0.58, 95% CI 0.34-0.99) less frequently, compared with male patients. No differences were present in rates of surgical septal myectomy, in-hospital mortality, ischemic stroke, major bleeding, and pericardial complication between groups.

Conclusions

Our results suggest that female patients were slightly more likely to undergo SRT, especially alcohol septal ablation. In-hospital mortality and postprocedural complications were similar between the sexes, but women received more pacemaker implantation and less ICD implantation.

Krüpple-like factors in cardiomyopathy: emerging player and therapeutic opportunities

Cardiomyopathy, a heterogeneous pathological condition characterized by changes in cardiac structure or function, represents a significant risk factor for the prevalence and mortality of cardiovascular disease (CVD). Research conducted over the years has led to the modification of definition and classification of cardiomyopathy. Herein, we reviewed seven of the most common types of cardiomyopathies, including Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC), diabetic cardiomyopathy, Dilated Cardiomyopathy (DCM), desmin-associated cardiomyopathy, Hypertrophic Cardiomyopathy (HCM), Ischemic Cardiomyopathy (ICM), and obesity cardiomyopathy, focusing on their definitions, epidemiology, and influencing factors. Cardiomyopathies manifest in various ways ranging from microscopic alterations in cardiomyocytes, to tissue hypoperfusion, cardiac failure, and arrhythmias caused by electrical conduction abnormalities. As pleiotropic Transcription Factors (TFs), the Krüppel-Like Factors (KLFs), a family of zinc finger proteins, are involved in regulating the setting and development of cardiomyopathies, and play critical roles in associated biological processes, including Oxidative Stress (OS), inflammatory reactions, myocardial hypertrophy and fibrosis, and cellular autophagy and apoptosis, particularly in diabetic cardiomyopathy. However, research into KLFs in cardiomyopathy is still in its early stages, and the pathophysiologic mechanisms of some KLF members in various types of cardiomyopathies remain unclear. This article reviews the roles and recent research advances in KLFs, specifically those targeting and regulating several cardiomyopathy-associated processes.

Integrated bioinformatics and experiment revealed that cuproptosis is the potential common pathogenesis of three kinds of primary cardiomyopathy

Cuproptosis is a recently reported new mode of programmed cell death which might be a potential co-pathogenesis of three kinds of primary cardiomyopathy. However, no investigation has reported a clear relevance between primary cardiomyopathy and cuproptosis. In this study, the differential cuproptosis-related genes (CRGs) shared by three kinds of primary cardiomyopathy were identified in training sets. As a result, four CRGs shared by three kinds of primary cardiomyopathy were acquired and they were mainly related to biological processes such as cell death and immuno-inflammatory response through differential analysis, correlation analysis, GSEA, GSVA and immune cell infiltration analysis. Then, three key CRGs (K-CRGs) with high diagnostic value were identified by LASSO regression. The results of nomogram, machine learning, ROC analysis, calibration curve and decision curve indicated that the K-CRGs exhibited outstanding performance in the diagnosis of three kinds of primary cardiomyopathy. After that, in each disease, two molecular subtypes clusters were distinguished. There were many differences between different clusters in the biological processes associated with cell death and immunoinflammation and K-CRGs had excellent molecular subtype identification efficacy. Eventually, results from validation datasets and in vitro experiments verified the role of K-CRGs in diagnosis of primary cardiomyopathy, identification of primary cardiomyopathic molecular subtypes and pathogenesis of cuproptosis. In conclusion, this study found that cuproptosis might be the potential common pathogenesis of three kinds of primary cardiomyopathy and K-CRGs might be promising biomarkers for the diagnosis and molecular subtypes identification of primary cardiomyopathy.

Aficamten: A Breakthrough Therapy for Symptomatic Obstructive Hypertrophic Cardiomyopathy

Aficamten is a novel cardiac myosin inhibitor that has demonstrated its ability to safely lower left ventricular outflow tract (LVOT) gradients and improve heart failure symptoms in patients with obstructive hypertrophic cardiomyopathy (HCM). Based on the REDWOOD-HCM open label extension (OLE) study, participants receiving aficamten had significantly reduced resting and Valsalva LVOT gradient within 2 weeks after initiating treatment, with ongoing improvements over 24 weeks, and recent evidence suggests effects can sustain up to 48 weeks. While beta-blockers, calcium channel blockers, and disopyramide have shown some benefits in managing HCM, they have limited direct impact on the underlying disease process in patients with obstructive HCM. Aficamten achieves its therapeutic effect by reducing hypercontractility and improving diastolic function in obstructive HCM. Mavacamten was the first cardiac myosin inhibitor approved for symptomatic obstructive HCM. However, aficamten has a shorter human half-life (t1/2) and fewer drug-drug interactions, making it a preferable treatment option. This review evaluates the long-term clinical value and safety of aficamten in patients with obstructive HCM based on available data from completed and ongoing clinical trials. Additionally, the molecular basis of sarcomere-targeted therapy in reducing LVOT gradients is explored, and its potential in managing obstructive HCM is discussed.

Revisiting Diagnosis and Treatment of Hypertrophic Cardiomyopathy: Current Practice and Novel Perspectives

Sarcomeric hypertrophic cardiomyopathy (HCM) is a prevalent genetic disorder characterised by left ventricular hypertrophy, myocardial disarray, and an increased risk of heart failure and sudden cardiac death. Despite advances in understanding its pathophysiology, treatment options for HCM remain limited. This narrative review aims to provide a comprehensive overview of current clinical practice and explore emerging therapeutic strategies for sarcomeric HCM, with a focus on cardiac myosin inhibitors. We first discuss the conventional management of HCM, including lifestyle modifications, pharmacological therapies, and invasive interventions, emphasizing their limitations and challenges. Next, we highlight recent advances in molecular genetics and their potential applications in refining HCM diagnosis, risk stratification, and treatment. We delve into emerging therapies, such as gene editing, RNA-based therapies, targeted small molecules, and cardiac myosin modulators like mavacamten and aficamten, which hold promise in modulating the underlying molecular mechanisms of HCM. Mavacamten and aficamten, selective modulators of cardiac myosin, have demonstrated encouraging results in clinical trials by reducing left ventricular outflow tract obstruction and improving symptoms in patients with obstructive HCM. We discuss their mechanisms of action, clinical trial outcomes, and potential implications for the future of HCM management. Furthermore, we examine the role of precision medicine in HCM management, exploring how individualised treatment strategies, including exercise prescription as part of the management plan, may optimise patient outcomes. Finally, we underscore the importance of multidisciplinary care and patient-centred approaches to address the complex needs of HCM patients. This review also aims to encourage further research and collaboration in the field of HCM, promoting the development of novel and more effective therapeutic strategies, such as cardiac myosin modulators, to hopefully improve the quality of life and outcome of patients with sarcomeric HCM.