[The electrocardiographic survey].
In order to investigate the prevalence of chagasic heart disease in Brazil, a national electrocardiographic survey was carried out from 1977 to 1981. A total of 5,347 electrocardiograms (ECG) were performed and paired by age and gender. The results obtained in relation with the autochthonous cases, were distributed by Brazilian states, as follows: Rio Grande do Sul (1,078), Minas Gerais (760), Bahia (612), Paraná (400), Paraiba (340), Piauí (218), Sergipe (216), Goiás (176), Pernambuco (170), Ceará (136) and Alagoas 134. The higher proportions of altered ECGs among seropositive individuals were found in the States of Goiás (63.6%), Minas Gerais (57.6%), Ceará (57.3%), Paraná (54.5%), Piauí (53.2%) and Paraiba (52.3%). Among the control individuals, these proportions were respectively 25%, 25.7%, 25%, 12.5%, 22.9% and 26.5%. A significant statistical difference of altered ECGs between positive and negative individuals was verified in all the States, with a single exception (Alagoas). The estimation of the gradient showed to be higher in Paraná State (42%), followed by Goiás (38.6%), Ceará (32.3%), Minas Gerais (31.9%), Piauí (30.3%), Paraíba (25.8%), Pernambuco (22.3%), Bahia (18.9%), Sergipe (16.7%), Rio Grande do Sul (9.9%) and Alagoas (7.5%). Concerning the distribution of the electrocardiographical alterations found in the eleven states, the main alterations find among the seropositive group were: ventricular extrasystoles, complete right bundle branch block, left anterior fascicular block, the association of complete right bundle branch block with left anterior fascicular block and primary alterations of the ST segment and of the T wave. Furthermore, these ECG alterations were more prevalent in the group of infected individuals.