Noninvasive prognostic markers for cardiac death and ventricular arrhythmia in long-term follow-up of subjects with chronic Chagas' disease

The objective of the present study was to investigate clinical, echocardiographic and electrocardiographic ( 12- lead resting ECG, 24-h ambulatory ECG monitoring and signal- averaged ECG ( SAECG)) parameters in subjects with chronic Chagas' disease in a long-term follow- up as prognostic markers for adverse outcomes. Fifty adult outpatients ( 34 to 74 years old, 31 females) staged according to Los Andes class I, II or III and complaining of palpitation were enrolled in a longitudinal study. SAECG was analyzed in time and frequency domains and the endpoint was a composite of cardiac death and ventricular tachycardia. During a follow- up of 84.2 +/- 39.0 months, 34.0% of the patients developed adverse outcomes ( 9 cardiac deaths and 11 episodes of ventricular tachycardia). After optimal dichotomization, in a stepwise multivariate Cox- hazard regression model, apical aneurysm ( HR = 3.7; 95% CI = 1.2- 1.3; P = 0.02), left ventricular ejection fraction < 62% ( HR = 4.60; 95% CI = 1.39- 15.24; P = 0.01) and incidence of ventricular premature contractions > 614 per 24 h ( hazard ratio = 6.1; 95% CI = 1.7- 22.6; P = 0.006) were independent predictors of the composite endpoint. Although a high frequency content in SAECG demonstrated association with the presence of left ventricular dysfunction and myocardial fibrosis, its predictive value for the composite endpoint was not significant. Apical aneurysms, reduced left ventricular function and a high incidence of ventricular ectopic beats over a 24- h period have a strong predictive value for a composite endpoint of cardiac death and ventricular tachycardia in subjects with chronic Chagas' disease.