A 35-year-old woman presents with exertional dyspnea and family history of sudden cardiac death. Echo shows asymmetric septal hypertrophy (28 mm), systolic anterior motion (SAM) of the anterior mitral leaflet, LVOT peak gradient 65 mmHg (obstruction), and preserved LVEF. What is the most appropriate first-line pharmacological therapy?
- A Beta-blocker (metoprolol succinate) ✓
- B ACE inhibitor
- C Verapamil
- D Mavacamten (cardiac myosin inhibitor)
Explanation
Obstructive hypertrophic cardiomyopathy (HCM) with LVOT gradient ≥50 mmHg causing symptoms is treated first-line with non-vasodilating beta-blockers (metoprolol or propranolol) — they reduce heart rate, decrease myocardial contractility, and reduce dynamic LVOT obstruction. This reduces symptoms in the majority. Verapamil is an alternative if beta-blockers are not tolerated. Mavacamten (cardiac myosin inhibitor, FDA-approved 2022, EXPLORER-HCM trial) reduces LVOT gradient and symptoms and is indicated for symptomatic obstructive HCM persistent despite beta-blocker — it is now increasingly used earlier in guidelines but beta-blocker remains first-line. Vasodilators including ACE inhibitors are contraindicated.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.