Survival After Secondary Prevention ICD Placement
What are the characteristics and risks of death of patients receiving a physician-designated secondary prevention implantable cardioverter-defibrillator (ICD) in contemporary clinical practice?
The study included patients enrolled in the National Cardiovascular Data Registry’s (NCDR) ICD Registry from 2006 to 2009 with a physician-designated secondary prevention indication for ICD implantation and linked to the Social Security Death Master File. Those patients with a history either of tachycardic arrest or sustained ventricular tachycardia (SCD/VT) or of syncope without SCD/VT were included. Kaplan-Meier survival analysis was used to assess mortality. Cox proportional hazards survival modeling was used to assess the risk of death in these groups, adjusting for patient characteristics.
The study cohort consisted of 46,685 patients (mean age 66 ± 14 years, 73.5% male, 85% white); 78% had SCD/VT and 22% had syncope. Overall mortality was 10.4% at 1 year and 16.4% at 2 years. Compared with patients having SCD/VT, the adjusted hazard of death at 1 year was lower in the patients having syncope (hazard ratio, 0.89; 95% confidence interval, 0.83-0.96), but was not significantly different by 2 years (hazard ratio, 0.96; 95% confidence interval, 0.90-1.01).
The authors concluded that nearly 9 of 10 patients receiving a secondary prevention ICD in clinical practice are alive 1 year after implantation.
This study reports that among patients enrolled in the NCDR ICD Registry who received an ICD for a secondary prevention indication, a substantial majority of patients had a documented secondary prevention indication, and most of those patients had documented SCD or sustained VT. Mortality approached 10% at 1 year, which is similar to mortality rates described in the secondary prevention randomized controlled trials. A limitation of this analysis is that it did not include a comparison cohort of patients not receiving an ICD to compare outcomes. Additional studies are needed to assess which populations receive the greatest benefit from secondary prevention ICD implantation. For now, current guidelines provide an important framework for decision making for clinicians.
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