Abstract
BACKGROUND: Patients with obstructive hypertrophic cardiomyopathy have increased symptomatic burden. Mavacamten was recently approved for treatment of obstructive hypertrophic cardiomyopathy based on 2 randomized controlled trials. However, its use under real-world conditions and in diverse populations is under-studied. METHODS AND RESULTS: This was a prospective observational cohort study of patients seen at the Johns Hopkins HCM center and prescribed mavacamten for obstructive hypertrophic cardiomyopathy between July 7, 2022 and January 6, 2024. Patients were followed longitudinally, with serial echocardiography and clinical evaluation as mandated by the risk evaluation and mitigation strategy program. Sixty-six patients received mavacamten (mean age 59 years, 47% male, 29% non-White [Black, Hispanic/Latino, Asian, Native Hawaiian or Pacific Islander], 47% obese). Before treatment, all patients had New York Heart Association class II (51.5%) or III (48.5%) heart failure symptoms. Initial maximum peak left ventricular outflow tract gradient was 107±46 mm Hg. Median treatment duration was 9 months. For patients on mavacamten after ≥6 months (n=43), symptoms improved by ≥1 New York Heart Association class in 72% of patients, and peak left ventricular outflow tract gradient decreased by 80±46 mm Hg, eliminating hemodynamically significant left ventricular outflow tract obstruction in 79.1% of patients. Mavacamten was temporarily discontinued in 3 patients due to left ventricular ejection fraction decrease <50%. There were no medication-related adverse events. Effectiveness and safety were similar between White and non-White patients, but symptomatic relief was attenuated in patients with body-mass index ≥35 kg/m(2). CONCLUSIONS: Mavacamten was effective and safe when used under real-world conditions in a racially diverse population of symptomatic patients with obstructive hypertrophic cardiomyopathy. Patients with comorbid obesity were less likely to experience symptomatic improvement while on mavacamten.