Mavacamten, a First-in-Class Cardiac Myosin Inhibitor for Obstructive Hypertrophic Cardiomyopathy

Objective: To assess mavacamten’s role in hypertrophic cardiomyopathy treatment. Data Sources: In addition to clinical guidelines, package inserts, and general reviews, we searched PubMed using the term mavacamten from inception to June 11, 2022. Study Selection and Data Extraction: English language studies describing mavacamten’s mechanism of action, pharmacokinetics, drug interactions, clinical and economic outcomes, and adverse events. Data Synthesis: Mavacamten reduces left ventricular outflow obstruction and New York Heart Association functional class while improving Kansas City Cardiomyopathy Questionnaire-Clinical Summary Scores in patients with obstructive hypertrophic cardiomyopathy. With an acquisition cost of $245.20 per capsule, it would cost $1.2 million for every additional quality-adjusted life year. In those with unobstructive hypertrophic cardiomyopathy, there were improvements in N-terminal probrain natriuretic peptide and high-sensitivity cardiac troponin biochemical markers. Mavacamten is a substrate for CYP2C19 and CYP3A4, and a CYP enzyme inducer. Relevance to Patient Care and Clinical Practice: Patients with obstructive hypertrophic cardiomyopathy and an ejection fraction ≥55% have a new option if they remain symptomatic despite maximally tolerated β-blocker or non-dihydropyridine calcium channel blocker therapy. It is an alternative to disopyramide therapy, which has poor patient tolerance, or septal reduction therapies, which are invasive. However, mavacamten is not cost-effective and its role in nonobstructive hypertrophic cardiomyopathy is not well established. Conclusions: Mavacamten is a new option for patients with refractory obstructive hypertrophic cardiomyopathy and an ejection fraction ≥55% but its pricing makes therapy not cost-effective. Final health outcomes are not fully elucidated and additional studies are needed to determine long-term effects.