Influence of patients' age at implantation on mortality and defibrillator shocks

Patients have increasing comorbidities and competing causes of death with advancing age, raising questions about the effectiveness of the implantable cardioverter defibrillators (ICD) in older age. We therefore investigated the effect of patients' age at initial device implantation on all-cause mortality and on the risk of ICD shocks in single-chamber (V-ICD), dual-chamber (D-ICD), and cardiac resynchronization therapy defibrillator (CRT-D) recipients.

We reviewed de-identified records of 67 128 ICD recipients enrolled in the Boston Scientific ALTITUDE database of remote monitored patients [V-ICD (n = 11 422), D-ICD (n = 23 974), and CRT-D (n = 31 732)]. Over a mean follow-up of 2.3 ± 1.4 years, patients in all ICD groups had increased all-cause mortality but decreased risk of defibrillator shocks and/or anti-tachycardia pacing per 10 year increase in age. Compared with the youngest age group (<50 years), patients in the oldest age group (≥80 years) had a 6.8-fold, 5.9-fold, and 3.4-fold increase in all-cause mortality (P < 0.001 for all comparisons) and a 31, 45, and 53% decrease in the risk of ICD shock (P ≤ 0.002 for all comparisons) for the V-ICD, D-ICD, and CRT-D groups, respectively.

Older recipients of standard and CRT defibrillators have higher mortality but fewer ICD shocks and/or therapies compared with younger patients. These data highly suggest less benefit of ICD therapy with increasing age, presumably because of competing risks of non-arrhythmic mortality. The role of defibrillator therapy in older patients may need to be evaluated with randomized controlled trials.