A Study to Evaluate Mavacamten Impact on Myocardial Structure in Participants With Symptomatic Obstructive Hypertrophic Cardiomyopathy

The purpose of this study is to evaluate the mavacamten impact on myocardial structure with cardiac magnetic resonance imaging (CMR) in adult participants with symptomatic obstructive hypertrophic cardiomyopathy (oHCM) \[New York Heart Association (NYHA) Functional Class II or III\].

Inclusion Criteria * Diagnosed with obstructive hypertrophic cardiomyopathy (oHCM), in accordance with current American College of Cardiology Foundation/American Heart Association and European Society of Cardiology guidelines as below:. * Left ventricular outflow tract (LVOT) peak gradient ≥ 30 mmHg and ≥ 50 mmHg after Valsalva or after exercise. * Left ventricular ejection fraction (LVEF) ≥ 55% at rest. * New York Heart Association (NYHA) functional class II or III symptoms. Exclusion Criteria * A known infiltrative or storage disorder causing cardiac hypertrophy that mimics oHCM. * Documented obstructive coronary artery disease or history of myocardial infarction. * A history of resuscitated sudden cardiac arrest or life-threatening ventricular arrhythmia within 6 months prior to screening. * An implantable cardioverter defibrillator (ICD) or pacemaker, or another contraindication for cardiac magnetic resonance imaging (CMR). * Other protocol-defined inclusion/exclusion criteria apply.