Primary vs Secondary Prevention Defibrillator Therapy in Octogenarians: A Clinical Equipoise of Survival, Cost and Complications

Background : In the multiple trials that established the efficacy of implantable cardiac defibrillator (ICD) in preventing sudden cardiac death, patients aged ≥ 80 years were poorly represented. One aspect of the paucity of data on outcomes in this subgroup pertains to any difference in survival based on the indication for the device, i.e. primary vs secondary prevention of ventricular arrhythmias. Methods : We performed a monocentric retrospective observational study of octogenarians receiving ICD therapy over a twelve-year period (n=95). Fisher exact and Chi-squared tests were used for categorical variables and student t-test and Wilcoxon rank-sum for continuous variables. A Kaplan-Meier survival analysis using logrank test and an adjusted Cox regression Hazard Ratio model was performed to compare survival between primary and secondary prevention groups. Results : Mean age of the cohort was 83.1 ± 3 years, with 85% (n=81) being male. 73% (n=69) of the participants had ischaemic cardiomyopathy and 43% (n=41) met the primary prevention indications. Overall survival at 5 years was 80% with a median survival time post device implantation at 27 months (IQR 12 – 55). The difference in survival rates between primary and secondary prevention was not statistically significant (p=0.63). Inappropriate shocks were delivered in 2 patients while 14 patients were successfully treated with appropriate therapy. Complications were encountered in 9.5% (n=9) of cases. Conclusion : In carefully selected octogenarians, there is no significant difference in the survival benefit conferred by ICD therapy based on the indication for the device. Advanced chronological age alone should not unduly influence the decision for ICD selection. There is an imperative for a greater representation of this cohort in future trials