A 35-year-old man is diagnosed with hypertrophic obstructive cardiomyopathy (HOCM). Echocardiogram shows asymmetric septal hypertrophy (septum 23 mm), systolic anterior motion (SAM) of the mitral valve, and LVOT gradient of 65 mmHg at rest. He is symptomatic with exertional dyspnoea. Which is the MOST appropriate pharmacotherapy?

• A Verapamil (non-dihydropyridine CCB) as first-line with careful monitoring
• B Disopyramide alone
• C Dihydropyridine CCB (amlodipine) to reduce afterload and relieve obstruction
• D Beta-blockers (metoprolol or propranolol) as first-line to reduce LVOT gradient ✓

Explanation

AHA/ACC 2020 HCM guidelines recommend beta-blockers as first-line for symptomatic HOCM with LVOT obstruction; they reduce heart rate, prolong diastole, decrease myocardial oxygen demand, and reduce dynamic LVOT obstruction. Verapamil is an alternative if beta-blockers are not tolerated. Disopyramide (negative inotrope) is added to beta-blockers for residual obstruction. Dihydropyridine CCBs (amlodipine, nifedipine) are contraindicated in HOCM as vasodilation can worsen outflow obstruction by reducing preload and afterload.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

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Written and medically reviewed by the StethoPrep medical team.