Low‐Dose Mavacamten Initiation in Obstructive Hypertrophic Cardiomyopathy: A Real‐World Study in China

Aims To evaluate the real‐world efficacy and safety of low‐dose (2.5 mg) mavacamten initiation in Chinese patients with symptomatic obstructive hypertrophic cardiomyopathy (oHCM). Methods and Results This single‐center observational study (Zhongshan Hospital, China; Oct 2024–Apr 2025) enrolled 72 symptomatic oHCM patients (NYHA II/III, LVEF ≥ 55%, resting/Valsalva‐provoked LVOT gradient [LVOTG] ≥ 30 mmHg). All patients initiated mavacamten 2.5 mg once daily. Doses were adjusted at Weeks 4, 8, and 12 based on LVEF and LVOTG. Primary outcomes were changes in resting/provoked LVOTG, NT‐proBNP, and NYHA class at Week 12. Safety outcomes included LVEF < 50%, cardiac hospitalization, and death. Significant reductions from baseline to Week 12 were observed: Resting LVOTG (52.4 ± 28.7 to 32.1 ± 23.1 mmHg, p < 0.001), Valsalva‐provoked LVOTG (74.1 ± 24.4 to 48.7 ± 25.4 mmHg, p < 0.001), NT‐proBNP (1102.7 ± 1114.9 to 320.2 ± 406.2 pg/mL, p < 0.001). LVEF remained stable. NYHA class improved by ≥ 1 class in 83.3% (60/72) of patients. Subgroup analyses revealed significantly greater LVOTG reductions in patients with classic HCM (vs. apical HCM, p < 0.001) and high baseline resting LVOTG (≥ 50 mmHg vs. < 50 mmHg, p < 0.001/ p = 0.04). NYHA improvement was consistent across subgroups. Twenty‐two patients escalated to 5 mg at Week 12, achieving further significant LVOTG reductions ( p < 0.001), particularly in apical HCM and high‐baseline‐gradient subgroups, with stable LVEF. No safety events occurred (LVEF < 50%, arrhythmias, hospitalization, and death). Four patients reported transient minor adverse events (dizziness, nausea, and fatigue). Conclusion In this first Chinese real‐world study, initiating mavacamten at 2.5 mg significantly improved haemodynamics (LVOTG), biomarkers (NT‐proBNP), and functional status (NYHA) in oHCM patients over 12 weeks with an excellent safety profile. Greater haemodynamic efficacy was observed in classic HCM and high‐baseline‐gradient patients. Escalation to 5 mg provided additional benefit. Mavacamten is an effective and safe therapy for oHCM in this Asian population.