Association of electrocardiographic abnormalities with seropositivity to Trypanosoma cruzi in Ecuador

Abstract
In highland Ecuador (province of El Oro), electrocardiograms (ECGs) were taken and analysed from 340 subjects, of whom 154 were seropositive to Trypanosoma cruzi by indirect haemagglutination test. Abnormal ECGs were present in 40.3% of seropositive individuals and 8.1% of seronegatives, and were slightly more common in seropositive males than in seropositive females. In seropositive individuals, the prevalence of abnormal ECG progressively increased with age and reached its peak level of 64.0% in the age group over 60 years, implying that Chagas disease in Ecuador produces little mortality among seropositive individuals. The most common ECG alterations were ventricular conduction defects: 26 of 117 seropositive individuals in the age group over 40 years had complete right bundle branch block. The frequency of atrioventricular block and arrhythmias was also associated with seropositivity to T. cruzi. A further ECG examination in lowland (province of Guayas) showed that the prevalence of abnormal ECGs there was significantly lower than that in highlands. These results suggest possible differences between T. cruzi strains in the two geographical areas of Ecuador.