OBJECTIVES

To study the evolution of lesions in conduction system using invasive electrophysiological studies (EPS), the impact of these alterations on cardiovascular events (CVE), and the frequency of these events in chronic chagasic patients. METHODS Prospective study, initiated in 1979 with clinical follow-up until 2000, with the participation of 28 chronic chagasic patients that were 18 to 65 years old, with bundle branch and/or atrioventricular blocks. The patients were submitted to two EPS with a minimum interval of four years between the studies in order to assess fi ve electrophysiologis parameters that were correlated with CVE. A 24-hour Holter and echocardiogram were performed. RESULTS The average follow-up time after the fi rst EPS was 154.5 months while the interval between EPS was 107.5 months. Ages ranged from 25 to 65 years. Twenty seven patients presented complete right bundle branch block associated with a left anterior hemiblock. The echocardiogram showed alteration in twelve patients. During the 24-hour Holter and ventricular stimulation, only one patient presented sustained ventricular tachycardia (SVT). Nine presented CVE during the study and only the HV interval ≥ 70ms presented a signifi cant statistical relationship with CVE. CONCLUSIONS a) The chronic form of Chagas disease presents different progressive abnormality percentages for the electrophysiological variables and WP alterations are the most common. b) Among the electrophysiological fi ndings, only the HV interval ≥ 70ms was associated with CVE. c) The incidence of CVE was 31.1 % during the average follow-up period of 154.5 months