This clinical trial is focused on studying a heart condition called Symptomatic Obstructive Hypertrophic Cardiomyopathy (oHCM). This condition involves the thickening of the heart muscle, which can make it harder for the heart to pump blood. The study will use a treatment called Mavacamten, which is taken as a capsule. Mavacamten is being tested to see if it can help reduce the thickness of the heart wall and the size of the upper heart chamber, known as the atria. The study will use a special imaging technique called Cardiac Magnetic Resonance (CMR) to look at changes in the heart’s structure.

The purpose of this study is to determine if Mavacamten can effectively reduce the thickness of the heart wall and the size of the atria in patients with oHCM. Participants in the study will be randomly assigned to receive either Mavacamten or a placebo, which is a capsule that looks like the medication but does not contain the active ingredient. The study will last for a period of 96 weeks, during which participants will have regular check-ups and imaging tests to monitor their heart condition.

Throughout the study, the impact of Mavacamten on heart function will be assessed, including any improvements in symptoms related to heart failure. The study will also monitor for any other heart-related events to ensure the safety of the treatment. The goal is to see if Mavacamten can provide a beneficial effect on the heart’s structure and function in people with oHCM.