Safety and efficacy of aficamten in patients with non‐obstructive hypertrophic cardiomyopathy: A 36‐week analysis from FOREST‐HCM

Aims The aim of this study was to report safety and efficacy of aficamten in patients with non‐obstructive hypertrophic cardiomyopathy (nHCM) over 36 weeks in the ongoing FOREST‐HCM trial. Methods and results Patients were started on aficamten 5 mg daily, with doses adjusted in 5‐mg increments (5–20 mg) at ≥2‐week intervals according to site‐read left ventricular ejection fraction (LVEF). Aficamten dose was increased if LVEF ≥55%, maintained if LVEF 50–54%, decreased if LVEF 40–<50%, and temporarily interrupted if LVEF <40%. Safety and efficacy were assessed over 36 weeks. Overall, 34 patients were enrolled (mean age 57.2 ± 15.3 years, 62% female, 41% in New York Heart Association [NYHA] class III). Over 36 weeks, 82.3% achieved 15–20 mg daily dose and there was a modest reduction in LVEF by −4.3% ± 5.2 from 70% ± 6.1 ( p < 0.0001). At Week 36, NYHA class improved by ≥1 class in 27 (79.4%) patients. Mean Kansas City Cardiomyopathy Questionnaire clinical summary score improved by 13.8 ± 12.5 points relative to baseline. Median (interquartile range) levels of N‐terminal pro‐B‐type natriuretic peptide were significantly improved from baseline (−665.5 pg/ml [−1244.0, −232.0]; p < 0.0001), while high‐sensitivity cardiac troponin I was unchanged (−2.7 ng/L [−11.3, 1.6]; p = 0.25). There were no drug discontinuations due to adverse events. LVEF <50% occurred in 2 (5.9%) patients, one following pulmonary vein isolation and one associated with atrial fibrillation. Conclusions Over 36 weeks, aficamten appeared safe and effective in the studied patients with nHCM.