Key Inclusion Criteria:

   - Males and females between 18 and 85 years of age, inclusive, at screening.

   - Body mass index <35 kg/m2.

   - Diagnosed with HCM per the following criteria:

      - Has LV hypertrophy and non-dilated LV chamber in the absence of other cardiac
      disease and

      - Has an end-diastolic LV wall thickness as measured by the echocardiography core
      laboratory of:

         - ≥15 mm in one or more myocardial segments OR

         - ≥13 mm in one or more wall segments and a known-disease-causing gene
         mutation or positive family history of HCM

   - Has resting LVOT-G ≥30 mmHg and post-Valsalva LVOT G ≥50 mmHg during screening as
   determined by the echocardiography core laboratory.

   - LVEF ≥60% at screening as determined by the echocardiography core laboratory.

   - NYHA Functional Class II or III at screening.

   - Hemoglobin ≥10g/dL at screening.

   - Respiratory exchange ratio (RER) ≥1.05 and pVO2 ≤90% predicted on the screening CPET
   per the core laboratory.

   - Patients on beta-blockers, verapamil, diltiazem, or disopyramide should have been on
   stable doses for >6 weeks prior to randomization and anticipate remaining on the same
   medication regimen during the trial. Patients treated with disopyramide must also be
   concomitantly treated with a beta blocker and/or calcium channel blocker.

Key Exclusion Criteria:

   - Known or suspected infiltrative, genetic or storage disorder causing cardiac
   hypertrophy that mimics oHCM (eg, Noonan syndrome, Fabry disease, amyloidosis).

   - Significant valvular heart disease (per investigator judgment).

      - Moderate-severe valvular aortic stenosis.

      - Moderate-severe mitral regurgitation not due to systolic anterior motion of the
      mitral valve.

   - History of LV systolic dysfunction (LVEF <45%) or stress cardiomyopathy at any time
   during their clinical course.

   - Inability to exercise on a treadmill or bicycle (eg, orthopedic limitations).

   - Has been treated with septal reduction therapy (surgical myectomy or percutaneous
   alcohol septal ablation) or has plans for either treatment during the trial period.

   - Documented paroxysmal atrial fibrillation during the screening period.

   - Paroxysmal or permanent atrial fibrillation is only excluded IF:

      - rhythm restoring treatment (eg, direct-current cardioversion, atrial fibrillation
      ablation procedure, or antiarrhythmic therapy) has been required ≤6 months prior
      to screening.

      - rate control and anticoagulation have not been achieved for at least 6 months
      prior to screening.

   - History of syncope or sustained ventricular tachyarrhythmia with exercise within 6
   months prior to screening.

   - Has received prior treatment with CK-3773274 or mavacamten.