RecruitingDrug trialEffect of Mavacamten Treatment on Coronary Flow Reserve in oHCMThe goal of this observational study is to measure the effect of mavacamten treatment on blood flow in the heart muscle (myocardium) in patients with obstructive hypertrophic cardiomyopathy. The main question it aims to answer is: • Does mavacamten treatment improve blood flow in the heart muscle? Participants will take mavacamten at the direction of their treating physician. Participants will complete 2 myocardial Positron Emission Tomography and Computed Tomography (PET-CT) scans. The first scan will be completed before participants start taking mavacamten. The scan will be repeated after 12 months of mavacamten treatment.