A 42-year-old man presents with dyspnea and syncope on exertion. Echocardiogram reveals asymmetric septal hypertrophy (IVS 22 mm), systolic anterior motion (SAM) of the mitral valve, and LVOT gradient of 60 mmHg at rest increasing to 110 mmHg on Valsalva. Mitral regurgitation is moderate. The LVEF is 72%. The most appropriate medical management as first-line is:
- A High-dose dihydropyridine calcium channel blocker (amlodipine)
- B Mavacamten (MyoKardia)
- C Septal reduction therapy (myectomy or alcohol ablation) immediately
- D Beta-blocker (metoprolol) or disopyramide as alternative ✓
Explanation
Hypertrophic obstructive cardiomyopathy (HOCM) first-line medical therapy is non-vasodilating beta-blockers (metoprolol, atenolol) which reduce heart rate (improving diastolic filling) and decrease LVOT gradient by reducing contractility and SAM. Verapamil (non-dihydropyridine CCB) is an alternative. Disopyramide (negative inotrope, anti-arrhythmic) is useful adjunctive therapy. Mavacamten (cardiac myosin inhibitor, EXPLORER-HCM trial) is a newer FDA-approved option for symptomatic obstructive HCM when beta-blockers fail, but is second-line. Dihydropyridines (amlodipine) cause vasodilation and are contraindicated. Septal reduction is for drug-refractory HOCM.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.