A Study of Mavacamten in Adults With Obstructive Hypertrophic Cardiomyopathy in India (ROVER)

Inclusion Criteria * Diagnosed with obstructive hypertrophic cardiomyopathy (HCM) consistent with current American College of Cardiology Foundation/American Heart Association and European Society of Cardiology guidelines. * Has unexplained LV hypertrophy with nondilated ventricular chambers in the absence of other cardiac (ie, hypertension, aortic stenosis) or systemic disease and with maximal LV wall thickness ≥ 15 mm (or ≥ 13 mm with positive family history of hypertrophic cardiomyopathy). * Has LVOT (Valsalva left ventricular outflow tract) peak gradient ≥ 50 mmHg during screening as assessed by TTE at rest or with Valsalva maneuver. * Has LVOT peak gradient with Valsalva maneuver at screening TTE of ≥ 30 mmHg. * Has adequate acoustic windows to enable accurate TTEs. * Has New York Heart Association (NYHA) Class II or III symptoms at screening. * Body weight is greater than 45 kg at screening. * Documentation of LVEF ≥ 55% at rest of screening TTE. Exclusion Criteria * Known infiltrative or storage disorder causing cardiac hypertrophy that mimics obstructive hypertrophic cardiomyopathy, such as Fabry disease, amyloidosis, or Noonan syndrome with LV hypertrophy. * Has paroxysmal atrial fibrillation present per the investigator's evaluation of the participant's ECG at the time of screening. * Has persistent or permanent atrial fibrillation not on anticoagulation for at least 4 weeks prior to screening and/or not adequately rate controlled within 6 months prior to screening. (Note: Participants with persistent or permanent atrial fibrillation who are anticoagulated and adequately rate-controlled are allowed). * Has a history of syncope with exercise within 6 months prior to screening. * History of sustained ventricular tachyarrhythmia (\> 30 seconds) within 6 months prior to screening. * Has documented obstructive coronary artery disease (\> 70% stenosis in one or more epicardial coronary arteries) or history of myocardial infarction. * Other protocol-defined Inclusion/Exclusion criteria apply.