Abstract 16912: The Incidence of the First Appropriate ICD Shock Remains Stable in Heart Failure Patients Over 6 Years
Introduction: Implantable cardioverter defibrillators (ICDs) are indicated for primary and secondary sudden cardiac death (SCD) prevention in patients with systolic heart failure (HF). Most ICDs are never used; it is not known whether subjects who have never had an appropriate ICD shock after several years are at decreased SCD risk.
Method: Data was collected on 384 subjects enrolled between March 2002 and November 2004 from one site of the Genetic Risk Assessment of Defibrillator Events (GRADE) study, a prospective observational study of subjects with severe systolic dysfunction (EF < 30%) and ICDs. The incidence of the first appropriate ICD shock for VT or VF and of death/transplant/VAD (DTV) was calculated for years 1 to 6.
Results: The cohort was 62±12 yrs old, 78% male, 95% white, 76% ischemic, EF 20±6 %, NYHA class 2.3±0.6, median f/u 43 months. 110 (29%) subjects reached the primary endpoint of appropriate ICD shock, and 186 (48%) reached the combined endpoint of DTV. The incidence of the first appropriate ICD shock was highest in year 1 (12.8%) but remained high through year 6 (6.8%; Figure). Similarly, the rate of DTV remained ~10% per year. Of note, 50% of subjects reached the combined endpoint of DTV within 1 year after their first appropriate shock.
Conclusion: The absence of an early appropriate ICD shock does not predict the absence of future shocks in HF patients. This likely reflects the progressive nature of HF in this cohort. Thus, ongoing generator changes should be recommended for subjects with low EFs, even in the absence of early appropriate shocks, as these patients remain at a substantial risk for SCD.
- Sudden cardiac death
- Implantable cardioconvert defibrillator
- Ventricular arrhythmia
- Heart failure
- Ejection fraction
- © 2011 by American Heart Association, Inc.