A Study of Mavacamten in Non-Obstructive Hypertrophic Cardiomyopathy

Inclusion Criteria

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.
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).
New York Heart Association (NYHA) Class II or III.

Exclusion Criteria

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.
History of unexplained syncope within 6 months prior to screening.
History of sustained ventricular tachyarrhythmia (> 30 seconds) within 6 months prior to screening.
Other protocol-defined Inclusion/Exclusion criteria apply.