Long‐Term Efficacy and Safety of Mavacamten in Chinese Patients With Obstructive Hypertrophic Cardiomyopathy: Week 78 Results From the EXPLORER‐CN Study

Journal of the American Heart Association, Volume 15, Issue 11 , June 2, 2026. BackgroundLong‐term efficacy and safety of mavacamten in Chinese patients with obstructive hypertrophic cardiomyopathy are unknown.MethodsPatients who completed the 30‐week, double‐blind, placebo‐controlled treatment period in EXPLORER‐CN (A Study to Evaluate the Efficacy and Safety of Mavacamten in Chinese Adults With Symptomatic Obstructive HCM), with no active safety concerns, were eligible to enter the long‐term extension period to receive 48‐week mavacamten treatment.

Patients previously on mavacamten continued mavacamten (dose at week 30; mavacamten–mavacamten group); patients previously on placebo received mavacamten (starting dose, 2.5 mg once daily; placebo–mavacamten group). Key efficacy end points included change from baseline in echocardiographic measures, New York Heart Association functional class, 23‐item Kansas City Cardiomyopathy Questionnaire Clinical Summary Score, and cardiac biomarkers through week 78.

Analyses were descriptive; no between‐group hypothesis testing was performed.ResultsSeventy‐nine patients (mean age, 51.6 years; 27.8% women) entered the long‐term extension period (mavacamten–mavacamten, n=54; placebo–mavacamten, n=25).