Natural history of chagasic cardiopathy in Chile. Follow-up of 71 cases after 4 years.

As part of study of Chagasic cardiopathy in Chile we report a follow-up study of 100 cardiopathic patients from two endemic areas who had been diagnosed 4 years earlier during an epidemiological and clinical survey. The follow-up consisted of a clinical, serological and electrocardiographic examination, and a continuous ECG recording for 60 min to detect possible arrhythmias. From the original 100 cases, three had died: one of a gastric cancer and the other two due to probable chagasic cardiopathy. Twenty-six had migrated to other areas and were lost to our study. From the remaining 71 patients, 48 were asymptomatic and 23 had complaints including palpitations, dyspnoea and Stokes-Adams crisis. In most cases, seropositivity by indirect haemagglutination did not change, but in six cases the titres decreased, becoming negative in three of them. Xeno-diagnosis was positive in 19.3% of seropositive patients. The ECG had returned to normal in 18 cases (17%) but showed a higher degree of blockades in others, three of which reached complete A-V block. The 60 min ECG was very important as it showed alterations in 93% of the cases, revealing arrhythmias that the ECG alone did not show. This work demonstrates that chagasic cardiopathy in Chile is a slow, progressive disease, that attacks the heart as a whole, but with special damage to the conducting tissues.