A 45-year-old man presents with progressive exertional dyspnea and palpitations. Echo shows asymmetric septal hypertrophy (IVS 20 mm, PW 9 mm), LVEF 70%, and dynamic LVOT obstruction with peak gradient 65 mmHg at rest. He is on maximal beta-blocker therapy. What is the next management step?
- A Refer for septal reduction therapy (surgical myectomy or alcohol septal ablation) ✓
- B Start a dihydropyridine calcium channel blocker (amlodipine)
- C Add mavacamten (cardiac myosin inhibitor) to reduce LVOT obstruction
- D Implant an ICD immediately as LVOT gradient >50 mmHg is an ICD indication
Explanation
In obstructive HCM (LVOT gradient ≥50 mmHg at rest or provocation) with severe symptoms (NYHA III-IV) despite maximal medical therapy (beta-blockers, disopyramide, non-dihydropyridine CCBs), septal reduction therapy is indicated. Surgical myectomy (Morrow procedure) is the gold standard for eligible patients. Alcohol septal ablation (ASA) is an alternative for older or high-surgical-risk patients. Mavacamten (EXPLORER-HCM trial, 2020) is a newer cardiac myosin inhibitor approved for symptomatic obstructive HCM in adults and can be tried before septal reduction, but this patient is already on maximal beta-blockade and should be referred for SRT. Amlodipine worsens LVOT obstruction. ICD indications are based on SCD risk score, not LVOT gradient alone.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.