In Reply We appreciate Rathod and colleagues’ comments regarding the health outcomes after implantable cardioverter-defibrillator (ICD) shocks among patients receiving an ICD for secondary prevention of sudden death. They emphasize important differences in health outcomes among primary prevention and secondary prevention patients.
While patients receiving primary prevention ICDs represent the majority of records in the National Cardiovascular Data Registry (NCDR) for ICDs (80%),1 substantial numbers of patients receive an ICD because they have survived sudden cardiac death or other life-threatening ventricular tachyarrhythmias. In addition, as Rathod and colleagues describe, the patient population undergoing primary prevention ICD implantation in the randomized clinical trials had lower ejection fractions and were on average older compared with those undergoing secondary prevention implantation in the Antiarrhythmics vs Implantable Defibrillators (AVID) trial.2- 4 Patients receiving an ICD for secondary prevention are much more likely to receive ICD therapies, including high-energy shocks and/or antitachycardia pacing in the context of the randomized clinical trial. The cumulative percentage of patients in AVID with either antitachycardia pacing or shock was 85% at 3 years, much higher than the 31% rate of ICD shocks at the mean follow-up of nearly 3.5 years among the primary prevention patients in the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT).2,3 Rates of device therapies in contemporary populations of patients receiving secondary prevention ICDs is not well described.
Borne RT, Varosy PD, Masoudi FA. Impact of Implantable Cardioverter-Defibrillator Therapy on a Secondary Prevention Population—Reply. JAMA Intern Med. 2013;173(22):2094. doi:10.1001/jamainternmed.2013.10385