Non-Invasive Detection of Subclinical Myocardial Involvement in Patients with Chronic Chagas' Infection

pp 311-320

Abstract

The chronic chagasic infection without overt clinical manifestations of myocardial damage is the least known but not less important period of the disease in terms of diagnosis and prognosis. Ten to 30% of the infected individuals develop a dilated myocardiopathy. Sudden death occurs not only in those with impaired myocardial function but also in totally asymptomatic patients. The early detection of patients prone to evolve into the most advanced forms of this cardiomyopathy is highly relevant in terms of developing new strategies for treatment and/or prevention of the chagasic myocardial aggression. Various non-invasive diagnostic techniques have been used to detect an early myocardial involvement not being displayed in the electrocardiogram. However, it is still unknown which of these techniques has greater sensitivity or specificity. Aiming to assess comparatively the ability of different non invasive techniques for the detection of early myocardial alterations in chronic Chagas' disease, 140 patients (78 male and 62 female) with positive serology for Chagas' disease were studied by means of lab analysis, resting electrocardiogram, chest X-ray, bidimensional echocardiography, stress testing, ajmaline test and 24-hour electrocardiogram Holter recording. The electrocardiogram was totally normal in 115 patients (82.1%)while some inespecific abnormalities were depicted in 25 (17.9%). The cardiothoracic ratio was normal in all patients. Forty five patients (32.1%) had ab-normalities in at least one of the non invasive studies. Twenty five patients developed abnormal electrocardiographic changes during the ajmaline test (17.8%; p < 0.001) and 16 patients (11.4%) had one or more abnormal findings in the 24-hour electrocardiogram Holter monitoring. One or more echocardiographic alterations were detected in 11patients (7.8%). The stress testing proved to be positive in only 2 patients(1.4%). Thirty one (26.9%) out of the 115 patients with undoubtedly normal resting electrocardiogram, showed abnormalities inat least one of the non invasive studies. The presence of non specific electrocardiographic alterations was closely related to the echocardiographic ones (p < 0.01). However, no correlation could be demonstrated among abnormal echocardiogram, positive ajmaline test, abnormal 24-hour Holter record-ing and abnormal stress testing. Abnormal electrocardiographic alterations prevailed in 30 year old-patients or older. The ajmaline test was more sensitive than the echocardiogram and the 24-hour electrocardiogram Holter recording to detect alterations in younger patients. Combined alterations in at least 2 out of the 4 non-invasive tests were observed in 10.5% of the 30-year or older patients and 1.5%in the younger ones. The results of this study indicate that the a positive ajmaline test is a more sensitive marker of myocardial damage than the B mode echocardiogram, the excercise stress testing and the 24 hour electrocardiogram ambulatory monitoring and allows detection of the chagasic myocardial involvement in the earlier stages. On the other hand, our findings suggest that the non-specific electrocardiographic alterations in patients suffering from Chagas' disease infection may indicate the presence of mild myocardial involvement.