This study is for patients with obstructive hypertrophic cardiomyopathy (oHCM). oHCM is a condition where the heart muscle becomes abnormally thickened, which can sometimes block the blood flow out of the heart and results in the heart muscle working harder to pump blood to the body.
The study is done to compare the side effects and effectiveness of an investigational (not yet approved by the Food and Drug Administration (FDA)) medication with the beta-blocker metoprolol succinate in participants with oHCM. The study medication is known as Aficamten and is a tablet taken by mouth. This is a randomized study (participants will be assigned by chance to the study medication Aficamten and placebo or metoprolol succinate and placebo). A placebo looks just like the study medication but has no active ingredient in it. The medications will be administered in the form of a pill. This study will take about 9 months and include about 11 visits to the study site. Study related procedures include blood work, echocardiograms (ultrasound test of the heart), electrocardiogram (recording of heart's electrical activity), exercise testing, physical exams, questionnaires and optional genetic testing. Risks associated with this study include shortness of breath, nausea, diarrhea, headaches and dizziness.