Effectiveness of Implantable Defibrillators in Octogenarians and Nonagenarians for Primary Prevention of Sudden Cardiac Death

Abstract

Given their advanced age and frequent co-morbidities, it is unclear whether octogenarians and nonagenarians with decreased left ventricular ejection fraction (LVEF) derive a survival benefit from implantable cardioverter-defibrillators (ICDs) in the primary prevention setting. The purpose of this study was to examine the effect of ICDs, age, and multiple co-morbidities on survival in elderly patients who otherwise meet implantation criteria for primary prevention of sudden cardiac death. Patients ≥80 years of age who received an ICD for LVEF ≤35% at our institution from 2001 through 2008 (n = 99) were compared to a cohort of patients ≥80 years of age with similarly low LVEF who did not receive an ICD (n = 53). Co-morbid conditions were assessed using the Charlson co-morbidity index (CCI). The overall cohort (n = 152, 84 ± 4 years old, 72% men, 87% with ischemic cardiomyopathy, LVEF 25 ± 7%, CCI 5.9 ± 3.2) was followed for 2.3 ± 2.0 years. Patients with ICDs were younger (82 ± 3 vs 86 ± 4 years, p <0.001) and had fewer co-morbidities reflected in a lower CCI (5.3 ± 3.1 vs 6.7 ± 3.1, p = 0.021). Patients with ICDs also had a trend toward lower LVEF (24 ± 6% vs 27 ± 7%, p = 0.06). During follow-up 93 (61%) patients died, 58 (59%) in the ICD group and 35 (66%) in the no-ICD group. ICD recipients had better 1-year survival compared to patients with no ICD (72% vs 52%, p = 0.014). However, after adjusting for age, LVEF, glomerular filtration rate (GFR), and CCI using multivariate Cox models, an ICD did not confer any survival benefit (hazard ratio 0.71, 95% confidence interval 0.42 to 1.20, p = 0.20), whereas age (p = 0.043) and GFR (p = 0.006) were the only independent predictors of survival. In conclusion, age and GFR are the main determinant of survival in octogenarians and nonagenarians with LV dysfunction. After correcting for these parameters, an ICD does not appear to confer a survival benefit.