A Study to Evaluate Mavacamten in Adults With Symptomatic Obstructive HCM Who Are Eligible for Septal Reduction Therapy

Key Inclusion Criteria: * At least 18 years old at screening and body weight \> 45 kg at screening * Diagnosed with oHCM consistent with current ACCF/AHA 2011 and meet their recommendations for invasive therapies * Referred or under active consideration within the past 12 months for SRT procedure and willing to have SRT procedure * Has documented left ventricular ejection fraction (LVEF) ≥ 60% at Screening * Has documented oxygen saturation at rest ≥ 90% at Screening Key Exclusion Criteria: * Persistent or permanent atrial fibrillation and subject not on anticoagulation for ≥ 4 weeks prior to screening and/or not adequately rate controlled ≤ 6 months prior to screening * Previously treated with invasive septal reduction (surgical myectomy or percutaneous alcohol septal ablation \[ASA\]) * For individuals on beta blockers, calcium channel blockers, or disopyramide, any dose adjustment of these medications \< 14 days prior to screening or an anticipated change in regimen during the first 16 weeks of the study * Any medical condition that precludes upright exercise stress testing * Paroxysmal, intermittent atrial fibrillation with atrial fibrillation present at screening * Prior treatment with cardiotoxic agents, such as doxorubicin or similar * Has a history or evidence of any other clinically significant disorder, condition, or disease that would pose a risk to subject safety or interfere with the study evaluation, procedures, or completion