Improved survival associated with prophylactic implantable defibrillators in elderly patients with prior myocardial infarction and depressed ventricular function: A MADIT-II substudy

Introduction: We aim to evaluate the mortality benefit from defibrillator therapy in eligible elderly patients. Effective primary prevention of sudden cardiac death with implantable cardioverter defibrillators is well demonstrated in patients with coronary disease and depressed ventricular function. Methods and Results: Among 1,232 patients enrolled with prior infarct and left ventricular ejection fraction ≤0.30, 204 were ≥75 years old. Of these 204 patients, 121 underwent defibrillator implant. Relative to the younger patients, those ≥75 years had a higher incidence of atrial fibrillation, elevated blood urea nitrogen (BUN), widened QRS, and lower use of beta-blockers and HMG-CoA reductase inhibitors. Relevant clinical covariates were similar in elderly patients randomized to conventional and defibrillator therapy. The hazard ratio for the mortality risk in patients ≥75 years assigned to defibrillator implant compared with those in conventional therapy was 0.56 (95 confidence interval 0.29-1.08; P = 0.08) after a mean follow-up of 17.2 months. Comparatively, the hazard ratio in patients <75 years assigned to defibrillator implant was 0.63 (0.45-0.88; P = 0.01) after 20.8 months. Elderly patients had similar reductions in quality of life (QoL) regardless of treatment randomization. Scores through Health Utilities Index Mark III (HUI) Questionnaire changes from baseline to 1 year were -0.22 for patients with conventional therapy versus -0.20 for patients with ICD, and -0.36 versus -0.27 at 2 years, respectively (P = NS). Conclusion: The implantable defibrillator is associated with an equivalent reduction of mortality in elderly and younger patients, with no compromise in the QoL in the older age subjects.