Efficacy and Safety of Implantable Cardioverter Defibrillator (ICD) Implantation in the Elderly (The I-70 Study)

Background There is conflicting evidence on the efficacy of primary prevention ICD implant in the elderly. Objective To determine the efficacy and safety of ICD implantation in patients 70 years and older. Methods Patients (n=167) age 70 years or older, and eligible for ICD implantation were randomly assigned (1:1) to receive either optimal medical therapy (OMT, n=85) or OMT plus ICD (n=82). Results Of the 167 participants (mean age: 76.4 years; 165 men), 144 completed the study protocol according to their assigned treatment. Average participant follow-up was 31.5 months. Mortality was similar between the two groups: (27 deaths in OMT versus 26 in ICD) unadjusted HR = 0.92, 95% confidence interval: 0.53 – 1.57 but there was a trend favoring the ICD over the first 36 months of follow-up. Rates of sudden death (7 versus 5, P=0.81) and all-cause hospitalization (2.65 events per participant in OMT versus 3.09 in ICD, P=0.31) were not statistically significantly different. Eleven participants randomized to ICD receiving appropriate therapy; five participants received an inappropriate therapy that included at least one ICD shock. Conclusion The study did not recruit to target sample size and accumulated data did not show benefit to ICD therapy in patients 70 years or older. Future similar in design studies might be feasible but will have to contend with patient treatment preference given the large number of patients who do not want an ICD implanted. Further research is needed to determine whether the ICD is effective in prolonging life among elderly device candidates.