A Study of Mavacamten in Non-Obstructive Hypertrophic Cardiomyopathy

Inclusion Criteria

1. Diagnosis of HCM consistent with current American College of Cardiology Foundation/American Heart Association and European Society of Cardiology guidelines: unexplained left-ventricular hypertrophy with non-dilated ventricular chambers in the absence of other cardiac or systemic disease which can produce the required magnitude of hypertrophy of a maximal left ventricular (LV) wall thickness ≥ 15 millimeters (mm) (or ≥ 13 mm with positive family history of hypertrophic cardiomyopathy [HCM]) as determined by core laboratory interpretation.
2. Peak left ventricular outflow tract (LVOT) pressure gradient < 30 millimeters mercury (mm Hg) at rest and < 50 mm Hg with provocation (Valsalva maneuver and stress echocardiography).
3. New York Heart Association (NYHA) Class II or III.

Exclusion Criteria

1. Known infiltrative or storage disorder causing cardiac hypertrophy that mimics non-obstructive hypertrophic cardiomyopathy (nHCM) such as Fabry disease, amyloidosis, or Noonan syndrome with LV hypertrophy.
2. History of unexplained syncope within 6 months prior to screening.
3. History of sustained ventricular tachyarrhythmia (> 30 seconds) within 6 months prior to screening.

* Other protocol-defined Inclusion/Exclusion criteria apply.