Abstract 16870: The Prognostic Impact of Appropriate Implantable Cardioverter Defibrillator Shock Based on Implant Indication: Insights From a Prospective, Population-based Registry in Ontario, Canada
Introduction: There are compelling data on the negative impact of appropriate implantable cardioverter defibrillator (ICD) shock on survival based on trials data. It is not known if this increased risk of death is seen in larger population-based studies and is applicable to various patient subsets. We examined the impact of appropriate ICD shock on survival between primary (1°) and secondary (2°) prevention recipients, in a large population registry.
Methods: We studied a prospective, multicenter, population-based registry from Ontario, Canada which included all patients who underwent de novo ICD implant between February 2007 and May 2012. The risk of death was compared between patients who received an appropriate ICD shock vs. those who did not. Adjustment of baseline characteristics was performed with multivariable Cox proportional hazard modelling and occurrence of an appropriate ICD shock was analyzed as a time-varying covariate. This analysis was performed in the 1° and 2° prevention ICD cohorts. In the pooled cohort, we performed a Cox model incorporating an interaction term of shock and implant indication to examine if the risk of death differed between 1° and 2° prevention patients after appropriate ICD shock.
Results: There were 5092 (70.3%) and 2152 (29.7%) patients with 1° and 2° prevention ICD. Compared to the 2° prevention group, patients in the 1° prevention group were older, had more medical comorbidities, and had lower left ventricular ejection fraction. In the 1° prevention group, the adjusted hazard ratio (HR) of death between those who had an appropriate ICD shock vs. those who did not was 1.92 (95% CI: 1.65-2.23, p<0.001). In the 2° prevention group, the adjusted HR of death between those with an appropriate ICD shock vs. those who did not was 1.54 (95% CI: 1.27-1.87, p<0.001). Amongst patients who experienced an appropriate ICD shock, there was no difference in mortality between the 1° and 2° prevention groups (HR, 1.26, 95% CI: 0.96-1.65, p= 0.093).
Conclusion: The greater risk of death amongst ICD recipients, after an appropriate shock, is demonstrable in a prospective population based registry, regardless of implant indication. After an appropriate shock, the risk of death was similar between patients with primary or secondary prevention ICD.
Author Disclosures: F. Almehmadi: None. A. Porta-Sanchez: Other; Modest; Fellowship support from ’la Caixa’ Foundation, Barcelona. Spain. H. Fisher: None. X. Wang: None. A. Ha: None. P.C. Austin: None. D.S. Lee: None. K. Nanthakumar: None.
- © 2016 by American Heart Association, Inc.