Novel Pharmacotherapy in Hypertrophic Cardiomyopathy

An Electromechanical Model-Based Study on the Dosage Effects of Ranolazine in Treating Failing HCM Cardiomyocyte

Background and Objective

Hypertrophic cardiomyopathy (HCM) is associated with a significant risk of progression to heart failure (HF). Extensive experimental and clinical research has highlighted the therapeutic benefits of ranolazine in alleviating electrophysiological abnormalities and arrhythmias in the context of HCM and HF. Despite these findings, there is a shortage of studies examining the electromechanical responses of failing HCM cardiomyocytes to ranolazine and the impact of ranolazine dosage on outcomes across varying degrees of HF. This study aims to systematically address these issues.

Methods

A computational modeling approach was utilized to quantify alterations in electromechanical variables within failing HCM cardiomyocytes subsequent to ranolazine treatment. The model parameters were calibrated against extant literature data to delineate the spectrum of HF severities and the changes in ion channels following the administration of various doses of ranolazine.

Results

The inhibition of the augmented late Na+ current in failing HCM cardiomyocyte with an adequate amount of ranolazine was found to be effective in alleviating electrophysiological abnormalities (e.g., prolongation of action potential (AP), Ca2+ overload in diastole), which contributed to improving the diastolic function of the cardiomyocyte, albeit with a modest negative effect on the systolic function. A threshold drug dose was identified for achieving a significant normalization of the overall electromechanical profile. The threshold drug dose for effective therapy was observed to be contingent upon the severity of HF and the status of certain key ion channels. Furthermore, it was determined that an increase of the drug dose beyond the threshold did not yield substantial additional improvements in the principal electromechanical variables.

Conclusions

The study demonstrated the presence of a threshold dose of ranolazine for effective treatment of failing HCM cardiomyocyte, and further established that this threshold is influenced by the severity of HF and the functional status of key ion channels. These findings may serve as theoretical evidence for comprehending the mechanisms underlying ranolazine's therapeutic efficacy in treating failing HCM hearts. Moreover, the study underscores the potential clinical value of personalized dosing strategies.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12195-025-00842-5.

Aficamten-A Second in Class Cardiac Myosin Inhibitor for Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy is an under-recognized disease with a genetic component that results in abnormal and often asymmetric thickening of the left ventricle in addition to decreased compliance and progressive fibrosis of the myocardium. It further poses significant complications related to dynamic left ventricular outflow obstruction over time in a significant majority. The medical management of obstructive hypertrophic cardiomyopathy has evolved over the decades as our understanding has grown. Traditionally, the mainstay in management has included the use of various negative inotropic agents. In contrast, the cardiac myosin inhibitors, aficamten and mavacamten, are novel therapies targeting cardiac contractility at the sarcomere level that have demonstrated improvement in clinical outcomes for patients, and mavacamten (Bristol Myers Squibb, Inc.) has now been approved by the Food and Drug Administration for the treatment of symptomatic obstructive HCM. Aficamten (Cytokinetics, Inc.) is the second in class cardiac myosin inhibitor that is currently being evaluated in ongoing phase III clinical trials, and is the subject of this review.

Mavacamten, an Alternative to Septal Reduction Therapy for Patients with Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a common heridetary cardiac disorder characterized by a wide range of symptoms. The pharmacological treatment of HCM is currently limited to beta blockers, non-dihydropyridine calcium channel blockers and disopyramide. Mavacamten is a novel cardiac myosin inhibitor, which was recently added to the limited pharmacological list of treatment options for HCM. This editorial elaborates on current evidence evaluating the use of mavacamten in patients with symptomatic obstructive HCM, comments on its current use and its expanded potential applications in the future.

Hypertrophic Cardiomyopathy: Current Treatment and Future Options

Hypertrophic cardiomyopathy (HCM) is a disease involving the cardiac sarcomere. It is associated with various disease-causing gene mutations and phenotypic expressions, managed with different therapies with variable prognoses. The heterogeneity of the disease is evident in the fact that it burdens patients of all ages. HCM is the most prevalent cause of sudden death in athletes. However, several technological advancements and therapeutic options have reduced mortality in patients with HCM to 0.5% per year. In addition, rapid advances in our knowledge of the molecular defects accountable for HCM have strengthened our awareness of the disorder and recommended new approaches to the assessment of prognosis. Despite all these evolutions, a small subgroup of patients with HCM will experience sudden cardiac death, and risk stratification remains a critical challenge. This review provides a practical guide to the updated recommendations for patients with HCM, including clinical updates for diagnosis, family screening, clinical imaging, risk stratification, and management.

Mavacamten: A First-in-class Oral Modulator of Cardiac Myosin for the Treatment of Symptomatic Hypertrophic Obstructive Cardiomyopathy

Hypertrophic cardiomyopathy is the most common monogenic cardiovascular disease that is caused by sarcomeric protein gene mutations. A hallmark of the most common form of the disease is outflow obstruction secondary to systolic narrowing of the left ventricular outflow tract from septal hypertrophy, mitral valve abnormalities and, most importantly, hyperdynamic contractility. Recent mechanistic studies have identified excessive myosin adenosine triphosphatase activation and actin-myosin cross-bridging as major underlying causes. These studies have led to the development of mavacamten, a first-in-class myosin adenosine triphosphatase inhibitor and the first specific therapy for hypertrophic obstructive cardiomyopathy. Preclinical and subsequent pivotal clinical studies have demonstrated the efficacy and safety of mavacamten. A remarkable improvement among treated patients in peak oxygen consumption, functional capacity, symptom relief and post-exercise left ventricular outflow tract gradient, along with dramatic reductions in heart failure biomarkers, suggests that this new medication will be transformative for the symptom management of hypertrophic obstructive cardiomyopathy. There is also hope and early evidence that mavacamten may delay or obviate the need for invasive septal reduction therapies. In this article, we review the current evidence for the efficacy and safety of mavacamten and highlight important considerations for its clinical use.

Hypertrophic cardiomyopathy: an up-to-date snapshot of the clinical drug development pipeline

INTRODUCTION

Hypertrophic cardiomyopathy (HCM) is a complex cardiac disease with highly variable phenotypic expression and clinical course most often caused by sarcomeric gene mutations resulting in left ventricular hypertrophy, fibrosis, hypercontractility, and diastolic dysfunction. For almost 60 years, HCM has remained an orphan disease and still lacks a disease-specific treatment.

AREAS COVERED

This review summarizes recent preclinical and clinical trials with repurposed drugs and new emerging pharmacological and gene-based therapies for the treatment of HCM.

EXPERT OPINION

The off-label drugs routinely used alleviate symptoms but do not target the core pathophysiology of HCM or prevent or revert the phenotype. Recent advances in the genetics and pathophysiology of HCM led to the development of cardiac myosin adenosine triphosphatase inhibitors specifically directed to counteract the hypercontractility associated with HCM-causing mutations. Mavacamten, the first drug specifically developed for HCM successfully tested in a phase 3 trial, represents the major advance for the treatment of HCM. This opens new horizons for the development of novel drugs targeting HCM molecular substrates which hopefully modify the natural history of the disease. The role of current drugs in development and genetic-based approaches for the treatment of HCM are also discussed.

Unique clinical features and long term follow up of survivors of sudden cardiac death in an Asian multicenter study

There has been no long-term clinical follow-up data of survivors or victims of sudden cardiac death (SCD). The Taiwan multi-center sudden arrhythmia death syndrome follow-up and clinical study (TFS-SADS) is a collaborative multi-center study with median follow-up time 43 months. In this cohort, the clinical characteristics of these SADS patients were compared with those with ischemic heart disease (IHD). In this SCD cohort, around half (42%) were patients with IHD, which was different from Caucasian SCD cohorts. Among those with normal heart, most had Brugada syndrome (BrS). Compared to those with SADS, patients with IHD were older, more males and more comorbidities, more arrhythmic death, and lower left ventricular ejection fraction. In the long-term follow-up, patients with SADS had a better survival than those with IHD (p < 0.001). In the Cox regression analysis to identify the independent predictors of mortality, older age, lower LVEF, prior myocardial infarction and history of out-of-hospital cardiac arrest were associated with higher mortality and beta blocker use and idiopathic ventricular fibrillation or tachycardia (IVF/IVT) with a better survival during follow-up. History of prior MI was associated with more arrhythmic death. Several distinct features of SCD were found in the Asia-Pacific region, such as higher proportion of SADS, poorer prognosis of LQTS and better prognosis of IVF/IVT. Patients with SADS had a better survival than those with IHD. For those with SADS, patients with channelopathy had a better survival than those with cardiomyopathy.

New perspectives in the pharmacological treatment of hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy is an inherited cardiac disease and a major cause of heart failure and sudden death. Even though it was described more than 50 years ago, sarcomeric hypertrophic cardiomyopathy still lacks a disease-specific treatment. The drugs routinely used alleviate symptoms but do not prevent or revert the phenotype. With recent advances in the knowledge about the genetics and pathophysiology of hypertrophic cardiomyopathy, new genetic and pharmacological approaches have been recently discovered and studied that, by influencing different pathways involved in this disease, have the potential to function as disease-modifying therapies. These promising new pharmacological and genetic therapies will be the focus of this review.

Chrysophanol attenuated isoproterenol-induced cardiac hypertrophy by inhibiting Janus kinase 2/signal transducer and activator of transcription 3 signaling pathway

Cardiac hypertrophy is a common pathological change found in various cardiovascular diseases. Although it has long been recognized as an important risk factor responsible for heart failure, there is still a lack of effective treatments in clinic. Chrysophanol is a natural compound with multiple biological activities and protective roles in the cardiovascular system. However, its potential effect on cardiac hypertrophy remains unclear. In the current study, we found that chrysophanol could protect against isoproterenol (ISO)-induced cardiac hypertrophy both in vitro and in vivo. Increase of cell surface and hypertrophic marker expression induced by ISO in neonatal rat cardiomyocytes was downregulated by chrysophanol. Moreover, chrysophanol ameliorated the abnormal changes of cardiac structure and function in rats subjected to ISO injection, as shown by echocardiography and morphometry measurements. Further mechanistical investigation demonstrated that chrysophanol inhibited phosphorylation of Janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3) induced by ISO. Nuclear translocation of STAT3 and transcription of downstream genes promoted by ISO treatment were also remarkably suppressed by chrysophanol. Taken together, our findings revealed that chrysophanol attenuated ISO-induced cardiac hypertrophy by inhibiting JAK2/STAT3 signaling pathway. Chrysophanol may be a potential candidate compound for the prevention and treatment of hypertrophy-related cardiomyopathy.