Abstract
BACKGROUND: The implantable cardioverter-defibrillator (ICD) is an effective therapy for preventing sudden cardiac death (SCD) in patients with prior myocardial infarction (MI) and reduced left ventricular function; however, the optimal timing of ICD implantation after MI remains unknown. OBJECTIVE: The purpose of this study was to determine whether the benefit of single-lead conservatively programmed ICD therapy varies as a function of time from MI to ICD implantation. METHODS: We compared time to all-cause death and SCD between the ICD and placebo arms in the Sudden Cardiac Death in Heart Failure Trial. Rates of appropriate shocks in the ICD arm were also assessed as a function of time after MI. RESULTS: Among the 712 patients with a history of MI, 274 died (38.5%), and 68 of these deaths were SCD (24.8%). Appropriate shocks were more common with increasing time after MI (adjusted hazard ratio [HR] per year after MI 1.04 [1.00-1.08]). Despite these differences, there was no evidence of differential mortality benefit with ICD implantation as a function of time after MI: continuous variable adjusted HR 1.00 [0.98,1.03] and shortest versus longest tertile adjusted HR 0.95 [0.66-1.34]. Sensitivity analyses also failed to show differential mortality benefit by quartile or with the use of an 18-month cutoff: <18 versus ≥ 18 months adjusted HR 1.08 [0.77, 1.51]. CONCLUSION: There is no evidence that ICD benefit varied with time from MI to implantation/randomization in this primary prevention population. Single-lead ICD benefit is not restricted to patients with a remote MI (>18 months).