Early ICD implantation limited to patients with inducible ventricular tachycardia enables a low overall mortality in patients with impaired LVEF after primary percutaneous coronary intervention for ST-elevation myocardial infarction.

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I mpaired left ventricular ejection fraction (LVEF) is one of the strongest predictors of death or arrhythmia postmyocardial infarction (MI). Randomized trials have demonstrated that post-MI patients with impaired LVEF derive a mortality benefit with implantation of a prophylactic implantable cardioverter-defibrillator (ICD) for prevention of sudden cardiac death (SCD).1,2 This mortality benefit is seen only in the chronic stage, with no randomized trial yet showing a benefit of early post-MI (within 40 days) ICD implantation.3,4 Current guidelines therefore limit prophylactic ICDs to patients who are >40 days post-MI with either LVEF ≤30% or LVEF ≤35% in the presence of New York Heart Association class II/III heart failure (HF).5 However, this risk-stratification method for prevention of SCD is limited by the poor specificity of impaired LVEF for arrhythmic versus nonarrhythmic cardiac death. 6 In addition, although the rate of SCD has declined in the era of early revascularization for MI, it remains concerningly elevated in the first 40 days.7-9 Inducible ventricular tachycardia (VT) at electrophysiological study (EPS) demonstrates the presence of a substrate for reentrant tachyarrhythmia and consistently predicts arrhythmia in observational and randomized studies. [10][11][12][13][14][15][16] The potential utility of EPS to guide early ICD implantation after MI has been demonstrated. 17,18Background-A negative electrophysiology study (EPS) may delineate a subgroup of patients with severely impaired left ventricular ejection fraction (LVEF) whose care can be safely managed long-term without an implantable cardioverter-defibrillator. Methods and Results-Consecutive patients treated with primary percutaneous coronary intervention for ST-segmentelevation myocardial infarction underwent early (median 4 days) LVEF assessment. Patients with LVEF ≤40% underwent EPS. A prophylactic implantable cardioverter-defibrillator was implanted for a positive (inducible monomorphic ventricular tachycardia) but not a negative (no inducible ventricular tachycardia or inducible ventricular fibrillation/ flutter) EPS result. Patients who would have become eligible for a late primary prevention implantable cardioverterdefibrillator with LVEF ≤30% or ≤35% with New York Heart Association class II/III heart failure were included and analyzed according to EPS result. Patients with LVEF >40%, ineligible for EPS, were followed up as control subjects (n=1286). The primary end point was survival free of death or arrhythmia (resuscitated cardiac arrest or sustained ventricular tachycardia/ventricular fibrillation). EPS performed in 128 patients with LVEF ≤30% or with LVEF ≤35% and heart failure was negative in 63% (n=80) and positive in 37% (n=48). Implantable-cardioverter defibrillators were implanted in <0.1%, 4%, and 90% of control, EPS-negative, and EPS-positive patients, respectively. The distribution of time to death or arrhythmia was comparable in control patients and EPS-negative patients with LVEF ≤30% or with LVEF ≤35% and heart fai...

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