Abstract 14880: Mortality, Appropriate and Inappropriate Shock in Patients with Ischemic Heart Disease and Implantable Cardioverter-Defibrillators for Primary Prevention: A Nationwide Cohort Study
Objective: To evaluate mortality and the incidence of appropriate- and inappropriate implantable cardioverter defibrillator (ICD) shocks as well as the associated risk factors in ICD patients with ischemic heart failure patients for primary prevention in a nationwide cohort.
Methods We identified 1731 patients who received their first ICD for primary prevention from January 1, 2007 - November 30, 2011 from the Danish ICD Register. Of these, 1609 (93%) had at least one follow-up visit. Time dependent multivariable Cox regression analyses were used to identify risk factors of inappropriate shock, appropriate shock and all-cause mortality.
Results: Average age at ICD implantation was 66±10 years and 84% (n=1349) were men. Mortality was 2.1% (n=194) during a mean follow-up of 1.9±1.3 years. Appropriate shocks occurred in 7.8% (n=126, mean follow-up 1.4 ±1.2 years). Of these, 56% (n=70) received >1 appropriate shock. Inappropriate shocks were identified in 2.6% (n=41, mean follow-up 1.3 ± 1.2 years) and 46% (n=19) received >1 inappropriate shock. Male gender was associated with risk of appropriate shocks (HR=4.0, CI:1.8-9.1). Dual-chamber ICD was associated with increased risk of inappropriate shocks compared to single-chamber ICD (HR=2.5; CI:1.2-5.1) (Figure). No similar risk was found for CRT-D (HR=0.84, CI:0.33-2.11) (Figure). Reduced left ventricular ejection fraction (<25%) was associated with increased of both inappropriate shocks and mortality (HR=2.7, CI:1.4-5.1 and HR=1.3, CI: 1.2-2.1, respectively). Appropriate- or inappropriate shocks were not associated with increased mortality.
Conclusion: In this nationwide cohort study of patients with a primary prevention ICD the incidence of appropriate as well as inappropriate shocks were lower than reported from randomized trials. Dual-chamber ICD was associated more inappropriate shocks and therapy compared to single chamber devices.
- © 2012 by American Heart Association, Inc.