Long-term follow-up of Chagas heart disease patients receiving an implantable cardioverter-defibrillator for secondary prevention.

BACKGROUND: Chagas heart disease (CHD) is a dilated cardiomyopathy characterized by malignant ventricular arrhythmias and increased risk of sudden cardiac death (SCD). Much controversy exists concerning the efficacy of implantable cardioverter-defibrillator (ICDs) in CHD because of mixed results observed. We report our long-term experience with ICDs for secondary prevention in CHD, with the specific aim of assessing the results in groups with preserved or depressed global left ventricular function.

METHODS: 111 patients (75 males; 60 ± 12 years) were followed for 1,948 ± 1,275 days after ICD. Time to death was the primary outcome; LVEF ≤ 45% the exposure; and age, gender, and ICD therapy delivery the potential confounders. We used time-to-event methods and Cox proportional models for analysis, censoring observations at time of death or at 5-year follow-up in survivors.

RESULTS: Seventy-two percent of the patients presented at least one sustained ventricular arrhythmia requiring appropriate therapy, and only three patients received inappropriate therapy. Death occurred in 50 (45%) patients, with an annual mortality rate of 8.4%, mostly due to refractory heart failure or noncardiac causes. Unadjusted survival rates were significantly distinct between patients with left ventricular ejection fraction (LVEF) ≤ 45% (26 deaths), 50.5% (95% confidence interval [CI]: 36.2%-63.2%) when compared to patients with LVEF > 45% (10 deaths), 77.6% (95% CI: 62.3%-87.3%, P < 0.01). After adjusting for confounders, low LVEF (hazard ratio [HR]: 5.2, 95% CI: 2.3-11.6), age (HR: 1.04, 95% CI: 1.01-1.07), and female gender (HR: 3.97, 95% CI: 1.85-8.54) were independently associated with the outcome.

CONCLUSIONS: ICDs successfully aborted life-threatening arrhythmias in CHD patients. Impaired left ventricular function predicted higher mortality in CHD patients with an ICD for secondary prevention of SCD.