Mavacamten to Aficamten Transition in Patients With Obstructive Hypertrophic Cardiomyopathy

Inclusion Criteria: * Documented history of oHCM with documented resting and/or Valsalva LVOT obstruction ≥ 50 mmHg who are currently receiving mavacamten commercially. * Echo-derived LVEF ≥55% on mavacamten at the time of enrollment. * Patient willing to consent for the study and undergo the study procedures. Exclusion Criteria: * Severe aortic stenosis or sub-aortic obstruction * Known infiltrative or storage disorder causing cardiac hypertrophy that mimics HCM (eg, Noonan syndrome, Fabry disease, amyloidosis). * History of LVEF \<30%. * Paroxysmal atrial fibrillation (AF) with documented episode within 3 months. * Atrial fibrillation (paroxysmal or permanent) not on systemic anticoagulation. * Documented history of current obstructive coronary artery disease (\> 70% stenosis in one or more epicardial coronary arteries) or documented history of myocardial infarction.