Inclusion Criteria: 1. Willing and able to provide written informed consent form (ICF) and any required privacy authorization prior to the initiation of study procedures. i. Diagnosis of obstructive HCM consistent with 2020 American Heart Association/American College of Cardiology (AHA/ACC) guidelines. ii. Obstructive HCM is defined clinically by the presence of increased LV wall thickness ≥ 15 mm (or ≥ 13 mm with positive family history of HCM) in a nondilated ventricular chamber that is not solely explained by abnormal loading conditions (eg, another cardiac or systemic disease) and peak LVOT gradient of ≥ 30 mmHg at rest or with provocation. 2. Has documented LVEF of ≥ 55% recorded by echocardiography within the last 6 months. 3. Symptoms consistent with NYHA functional class II-IV. 4. ≥ 18 years of age at the time of informed consent. 5. Receiving BBs, non-dihydropyridine calcium. channel blockers (non-DHP CCBs), disopyramide, and/or mavacamten (once available) as part of routine clinical care; or currently receiving no treatment due to intolerance or failure of prior treatment (eg, BBs, non-DHP CCBs, or disopyramide) for obstructive HCM. Exclusion Criteria: 1. Known phenocopy disease (eg, Fabry disease, amyloidosis) or LV hypertrophy associated with hypertension. 2. Documentation of any fixed obstruction of the outflow tract such as aortic valve stenosis or replacement. 3. Prior treatment of obstructive HCM with invasive septal reduction (surgical myectomy or percutaneous alcohol septal ablation [ASA]) within 6 months prior to enrollment; participants with an unsuccessful myectomy or percutaneous ASA performed > 6 months prior to enrollment may be enrolled. 4. Naïve to treatment for obstructive HCM (ie, never treated with BBs, non-DHP CCBs, or disopyramide). 5. Receiving an investigational therapeutic agent for obstructive HCM (eg, myosin-inhibitors other than mavacamten) in an interventional clinical trial at participant enrollment. 6. Previously or currently enrolled in a long-term safety extension study of mavacamten (eg, EXPLORER-HCM [ClinicalTrials.gov, NCT03470545], MAVA-LTE [NCT03723655], PIONEER-OLE [NCT03496168], VALORHCM [NCT04349072], or MAVERICK [NCT03442764])