Mavacamten in Obstructive Hypertrophic Cardiomyopathy: National Insights on Access and Safety Profile From Real-World Data

BACKGROUND: Mavacamten improves symptoms in obstructive hypertrophic cardiomyopathy, but real-world prescription patterns, safety profile, and the effect of atrial fibrillation (AF) on outcomes remain unclear. METHODS: An observational multicenter analysis using patient-level data from the TriNetX database (2011–2023) compared patients with obstructive hypertrophic cardiomyopathy treated with mavacamten versus those not treated with mavacamten (controls). Multivariable logistic regression identified predictors of mavacamten use. Propensity-score matching was used to reduce confounding bias. Outcomes included acute heart failure, left ventricular systolic dysfunction, cardiovascular hospitalization, new-onset AF, and all-cause mortality. Outcomes were also stratified by AF history. RESULTS: Among 15 145 patients, 509 (3.5%) received mavacamten; 502 matched to 1475 weighted 1:3 controls (equivalent to 502). Black patients were significantly less likely to receive mavacamten compared with White patients (odds ratio, 0.45 [95% CI, .0-33.63]). Of the 502 mavacamten recipients, 4.8% experienced acute heart failure, 8.3% experienced systolic dysfunction, 10.8% experienced cardiovascular hospitalization, 6.4% experienced new-onset AF, and 1.4% died. Overall outcomes were similar between both groups except for a higher incidence of systolic dysfunction in mavacamten patients (log-rank P<0.001). Among mavacamten patients, those with baseline AF (28%) had significantly higher rates of acute heart failure (7.8% versus 3.6%; P=0.047), systolic dysfunction (12.8% versus 6.4%; P=0.02), cardiovascular hospitalization (27.7% versus 4.2%; P<0.01), and mortality (5% versus 0%; P<0.01). Older age independently predicted acute heart failure, whereas baseline AF predicted both cardiovascular and all-cause hospitalization. CONCLUSIONS: Black patients have markedly lower access to mavacamten. Preexisting AF was associated with a higher risk of adverse outcomes for patients on mavacamten, highlighting the need for careful monitoring.