Abstract 2139: Does Statin Use Predict Appropriate Implantable Cardioverter Defibrillator Therapy?
Although implantable cardioverter defibrillator (ICD) placement has been established as the most effective primary or secondary therapy to reduce mortality from sudden cardiac death, most patients with an ICD do not receive therapy (antitachycardia pacing [ATP] or shock). The goals of this study were to determine the ICD event rate at our institution and to identify clinical predictors of appropriate and inappropriate ICD therapy. Medical and device interrogations records were reviewed retrospectively for 238 consecutive patients who underwent first-time ICD placement from August 2004 to December 2006 at Scripps Clinic. Outcome variables were time from implant to first appropriate and time from implant to first inappropriate ICD therapy. Cox regression analysis was used to identify predictors of appropriate and inappropriate therapy. The mean age at implant of 238 patients studied was 71±12 years and the mean follow-up was 1.5±0.9 years. Appropriate ICD therapy occurred in 17% of patients at 1 year and 29% at 2 years. The only predictor of an appropriate ATP or shock was statin use at the time of implant, with a relative risk (RR) of 2.7 (95% CI: 1.1– 6.3). Patients who had an implant for primary prevention and were not on a statin at the time of implant were significantly less likely to have an appropriate ICD event. Appropriate therapy was found to be independent of etiology of cardiomyopathy (RR 0.8; 95% CI 0.4 –1.6). In addition, there was no interaction between statin use and ischemic or non-ischemic etiology of cardiomyopathy. Ejection fraction was not a predictor of ICD events. The rates of an inappropriate ICD event were 9% and 15% at 1 and 2 years, respectively. There were no statistically significant predictors of inappropriate therapy. In this study, statin use at implant, and not ejection fraction, was the only predictor of subsequent appropriate ICD therapy, and was independent of the etiology of cardiomyopathy.
This finding is contrary to previously published reports although the 1-year appropriate ICD event rate was similar to prior studies. There were no significant predictors of inappropriate ICD therapy.