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