Efficacy and Safety of an LVEF-Guided Mavacamten Dose Up-Titration Strategy in Chinese Patients With Symptomatic Obstructive Hypertrophic Cardiomyopathy

Efficacy and Safety of a Left Ventricular Ejection Fraction-Guided Mavacamten Dose Up-Titration Strategy in Chinese Patients With Symptomatic Obstructive Hypertrophic Cardiomyopathy: A Prospective, Multicenter, Open-Label Study

This study aims to evaluate whether, under a treatment strategy primarily guided by left ventricular ejection fraction (LVEF), dose up-titration in adult patients with symptomatic obstructive hypertrophic cardiomyopathy who have received Mavacamten treatment for at least 12 weeks with a stable maintenance dose (as baseline) and with LVEF ≥55% can further reduce left ventricular outflow tract (LVOT) gradient after 24 weeks of treatment. It will also assess changes in hemodynamics, clinical symptoms, cardiac structure, and function. Furthermore, the study will conduct stratified analyses based on patients' baseline resting or Valsalva-provoked LVOT gradient levels at enrollment [<30 mmHg vs. ≥30 mmHg] to explore differences in the aforementioned outcome measures among patients with different gradient levels, with the goal of providing evidence for individualized clinical dose adjustment.

Inclusion Criteria:

• 1. Adult patients diagnosed with obstructive hypertrophic cardiomyopathy (HCM) and classified as New York Heart Association (NYHA) functional class II-III. 2. Have received stable Mavacamten treatment for at least 12 weeks with a stable dose. 3. LVEF ≥ 55%.

Exclusion Criteria:

• 1. Hypertrophy caused by other systemic diseases with a clear etiology. 2. Planned use of strong CYP2C19 inhibitors, moderate to strong CYP2C19 inducers, or CYP3A4 inducers during the study. 3. Planned use of disopyramide, ranolazine, verapamil combined with beta-blockers, or diltiazem combined with beta-blockers during the study. 4. Previous intolerance to Mavacamten. 5. Severe hepatic or renal dysfunction. 6. Pregnant or lactating women.