Background: Randomized clinical trials (RCTs) have
demonstrated the efficacy of implan-table cardioverter-
defibrillators (ICDs) in reducing sudden cardiac
death (SCD) in specific patient populations. However,
patients ≥ 65 years were under-represented in
these trials and the overall benefit of ICDs may be
diminished in older patients due to competing risks
for death. We evaluate the published data on ICD
efficacy at reducing all-cause mortality in patients
≥ 65 years and in patients ≥ 75 years.

Methods: We searched MEDLINE to identify RCTs
and observational studies of ICDs that provided agebased
outcome data for primary prevention of SCD.
The primary endpoint was mortality evaluated by
a meta-analysis of the RCTs using a random-effects
model. Secondary endpoints included operative
mortality, long-term complications and quality of life.

Results: The enrollment of patients ≥ 65 years in
RCTs was limited (range: 33% in DEFINITE to 56% in
MUSTT). Combining data from four RCTs (n = 3,562)
revealed that primary prevention ICD therapy is efficacious
in reducing all-cause mortality in patients
≥ 65 ye-ars (HR 0.66; 95% CI 0.50–0.87; test of heterogeneity:
X2 = 5.26; p = 0.15). For patients ≥ 75
years, combining data from four RCTs (n = 579) revealed

that primary prevention ICD therapy remains efficacious in reducing all-cause mortality (HR 0.73; 95% CI 0.51–0.974; p = 0.03). There appears to be no difference in ICD-related, operative, in-hospital, or
long-term complications among older patients compared
to younger patients, although it remains unclear
if older patients have a better quality of life with
an ICD than younger patients.

Conclusions: Although the overall evidence regarding
ICD efficacy in patients ≥ 65 years is limited and
divergent, and the evidence available for patients
≥ 75 years is even more sparse, our meta-analysis
suggests that primary prevention ICDs may be beneficial
in older patients. Our findings need to be
validated by future studies, particularly ones examining
ICD complications and quality of life.