Real‐World Observations in Patients With Obstructive Hypertrophic Cardiomyopathy Treated With Mavacamten: Evidence of Favorable Disease Modification

Background Mavacamten is commercially approved for use in symptomatic patients with obstructive hypertrophic cardiomyopathy. This study evaluated its real‐world impact on symptoms, echocardiographic changes, and the need for septal reduction therapy in patients with obstructive hypertrophic cardiomyopathy treated at a multihospital referral center. Methods We included 244 patients with obstructive hypertrophic cardiomyopathy (mean age, 64 years; 57% women, 21% with atrial fibrillation, 51% New York Heart Association class III, 82% on β‐blockers) treated with mavacamten for ≥3 months (171 for ≥12 months). Serial clinical and echocardiographic assessments were performed. Results New York Heart Association class distribution improved over time: at 3 months 21% class I, 61% class II, and 18% class III; at 12 months 36% class I, 57% class II, and 8% class III. After a mean of 1.02 years, significant improvements were observed in resting and post‐Valsalva left ventricular outflow tract gradients (−31±33 and −57±46 mm Hg), interventricular septal thickness (−1.7±4 mm), left ventricular mass index (−9.5±32 g/m 2 ), left atrial volume index (−12±13 mL/m 2 ), E/e′ (−5.5±6.4), left ventricular global longitudinal strain (1.04%±3.1%), and various left atrial and right ventricular strain measures (all P <0.05). Temporary interruption occurred in 8 patients (3.2%), and 3 (1.2%) discontinued mavacamten permanently. There were 2 noncardiac deaths, 7 heart failure admissions, 14 cases of new‐onset atrial fibrillation, and 1 patient required septal reduction therapy. At the last visit, most patients were on 5 mg (49%) or 10 mg (26%) mavacamten. Conclusions In this real‐world cohort, mavacamten treatment was associated with sustained symptomatic and echocardiographic improvements, suggesting a favorable disease‐modifying impact with minimal need for septal reduction therapy.