Mortality risk score for patients with Chagas cardiomyopathy and pacemaker

Abstract

Background Prognosis of Chronic Chagasic Cardiomyopathy (CCC) patients depends on functional and clinical factors. Bradyarrhythmia requiring pacemaker is a common complication. Prognosis of these patients is poorly studied, and mortality risk factors are unknown. We aimed to identify predictors of death and to define a risk score for mortality in a large cohort of CCC patients with pacemaker. Methods It was an observational, unicentric and prospective study. The endpoint was all-cause mortality. Cox regression was used to identify predictors of death and to define a risk score. Bootstrapping method was used to internal score validation. Results We included 555 patients and after a mean follow-up of 3.7±1.5 years, 100 (18%) deaths occurred. Predictors of death were: Right ventricular dysfunction (HR [hazard ratio] 2.24; 95%CI 1.41–3.53; P = 0.001); heart failure class III or IV (HR 2.16; 95% confidence interval [95%CI] 1.16–4.00; P = 0.014); renal disease (HR 2.14; 95%CI 1.24–3.68; P = 0.006); left ventricular end-systolic diameter > 44mm (HR 1.97; 95%CI 1.26–3.05; P = 0.003); atrial fibrillation (HR 1.94; 95%CI 1.25–2.99; P = 0.003) and cardiomegaly on X-ray (HR 1.87; 95%CI 1.10–3.17; P = 0.020). The score identified patients with: Low (0–20 points), intermediate (21–30 points) and high risk (>31points). The optimism-corrected C-statistic of the predictive model was 0.751 (95% CI 0.696– 0.806). Internal validation with bootstrapping revealed a calibration slope of 0.946 (95% CI 0.920–0.961), reflecting a small degree of over-optimism and C-statistic of 0.746 (95% CI 0.692–0.785).