A 58-year-old man suffered an anterior STEMI 10 days ago. Echocardiography shows a left ventricular ejection fraction of 28% despite optimal medical therapy including beta blocker and ACE inhibitor. He is asymptomatic and in sinus rhythm. When should an ICD be implanted for primary prevention of sudden cardiac death in this patient?
- A At 40 days or more after the myocardial infarction ✓
- B Immediately, before hospital discharge
- C Only after documented sustained ventricular tachycardia
- D At 6 months, regardless of repeat ejection fraction
Correct answer: A. At 40 days or more after the myocardial infarction
Explanation
Guidelines require waiting at least 40 days after MI before ICD implantation for primary prevention when EF is 35% or less, because early revascularization recovery often improves ejection fraction substantially and early implantation showed no mortality benefit in the DINAMIT trial. The decision is based on reduced EF alone, not on prior sustained ventricular tachycardia, which would itself indicate a secondary prevention device. If EF recovers above 35% on reassessment, implantation is deferred.
Reference: Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 12th ed.
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Written and medically reviewed by the StethoPrep medical team.