Averaged-signal electrocardiography in Chagas disease

pp 93-102

Abstract

Chagas disease is associated with a high incidence of arrhythmias. We studied the presence of ventricular late potentiales (LP), 8 well known predictor of malignant ventricular arrhythmias and sudden death, in patients with Chagas' disease. We prospectively evaluat-ed 84 patients (59 women, 25 men; 48 ± 16 years) with positive serology for Chagas disease. Signal-averaged ECG were analyzed with time domain in patients without bundle branch block (n = 61), and frequency domain (FFT) in all patients. According to cardiac involvement patients were classified into four groups: A, B, C and D, and the results obtained were compared with a control group of 40 normal volunteers. The incidence of LP in patients with Chagas disease varied according to the method used. When the classic system was used (time domain in patients without bundle branch block and FFT in patients with it) LP were present in 27 patients (32.1 %). When all patients were studied with FFT high frequency components were found in 34 (40.4 %). When comparing this results with those of the healthy volunteers we observed a significant difference. There were no statistically significant difference between groups with overt heart disease (groups B, C and D), but the presence of LP were more frequent in those presenting ECG and/or Holter abnormalities, comparing with those without heart disease or ventricular dysfunction (p < 0.05). We also found differences when comparing the group of healthy volunteers with the group A using FPT (p < 0.05). We conclude that: a) LP are frequently found in patients with Chagas' disease and in an important number of completely asymptomatic patients and b) in patients with chagasic heart disease there is a direct relationship between the presence of LP and ECG changes and ventricular arrhythmias present at Holter monitoring, but there is no such relationship with the presence of ventricular dysfunction.