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

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).

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).

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.