Abstract 2037: Renal Dysfunction and Appropriate Shock Therapy in Implantable Cardioverter Defibrillator Patients with Nonischemic Heart Failure
Background: Implantable Cardioverter Defibrillator (ICD) prevent sudden cardiac death in high risk patients with heart failure. The presence of coexisting conditions has a substantial effect on the rate of arrhythmic events in heart failure patients. Renal dysfunction is associated with mortality in patients with myocardial infarction or heart failure, but the influence of degrees of renal impairment is less well defined.
Methods: A total of 221 patients who underwent ICD implantation were included between 1990 and 2006. Gromerular Filteration Rate (GFR) was estimated using the Modification of Diet in Renal Disease (MDRD) and renal insufficiency was defined as MDRD GFR<60mL/min/1.73m2. Differences in arrhythmia recurrences according to the MDRD GFR were compared by Kaplan-Meier survival curves.
Results: During a mean follow-up time of 3.7±2.8 years, 82 (37%) of 221 patients (mean age; 4.7±1.3 years, 71% male) experienced appropriate ICD shock therapy. There was a trend of higher cumulative rate of appropriate ICD shock therapies in patients with renal insufficiency than other patients (p<0.10). The result of subgroup analysis of 94 patients with low LVEF (LVEF<35%) indicated that the patients with renal insufficiency experienced electrical storms more frequently (p<0.05). After correcting for age, sex, left ventricular ejection fraction (LVEF), indication for ICD implantation, and use of beta-blockers in a Cox regression model, low MDRD GFR was still an independent predictor of the time to first appropriate ICD shock (hazard ratio [HR] 2.30, 95% confidence interval [CI] 1.13–4.69, p<0.05). Below 60mL/min/1.73m2, each reduction of the MDRD GFR by 10 units was associated with a HR for appropriate shock of 1.40 (95% CI, 1.00 to 1.95).
Conclusion: Renal insufficiency is associated with increased rate of arrhythmic event in nonischemic HF patients. Especially, those patients with low LVEF and renal dysfunction experience more frequent ICD shocks.