Mavacamten Enables Exercise in Hypertrophic Obstructive Cardiomyopathy

Inclusion Criteria: * Age ≥18 years of age * Diagnosis of hypertrophic obstructive cardiomyopathy * ≥12 weeks of unchanged dosage of mavacamten * Peak left ventricular outflow tract gradient ≤ 50 mmHg at rest and during stress echocardiography * Left ventricular ejection fraction ≥50% at study inclusion * New York Heart Association classes I-II Exclusion Criteria: * Syncope or sustained ventricular tachycardia within 6 months prior to study inclusion * Corrected QT-interval (Fridericia-formula) ≥ 500 ms * Paroxysmal or intermittent atrial fibrillation (AF) on screening electrocardiogram * Persistent or permanent AF without anticoagulation for ≥4 weeks * Previous transcoronary ablation of septal hypertrophy or surgical myectomy * Ventricular tachycardia, significant ST-elevation or depression upon baseline cardiopulmonary exercise testing * ≥ grade II valve insufficiencies or stenoses during resting echocardiography * Prior implantable cardioverter defibrillator-implantation * Sudden Cardiac Death Risk Score ≥4%