Clinical Characteristics

Some cardiac involvement probably occurs in virtually all patients with acute Chagas' disease, but is usually unrecognized. The clinical manifestations resemble myocarditis from other causes. Most patients have transient cardiac insufficiency with slight to moderate reversible cardiac enlargement. More severe right and left-sided failure may occur with pulmonary and systemic congestion, tachycardia, gallop rhythm, Stokes-Adams syndrome, premature ventricular contractions, hypophonetic heart sounds, and a systolic murmur in the mitral area. The systolic blood pressure and pulse pressure are decreased.

Echocardiography, serial chest radiographs, and electrocardiograms provide the most accurate methods of detecting acute myocarditis and of assessing the degree of involvement. ECG abnormalities were noted in 78 of 180 patients with acute Chagas' disease studied by Laranja; 21 of these patients died. The most common findings include a prolongation of the P-R interval, primary T wave changes, low voltage QRS, prolonged Q-T interval, and associated ST-T changes.

These changes are usually reversible and, in most patients, symptoms disappear within 2-3 months, although some patients (probably 15%) continue to have residual ECG abnormalities. The fever usually subsides within 4 to 5 weeks; the parasites disappear from the peripheral blood and Romaña's sign and the chagoma disappear within 1 month, but hepatosplenomegaly may persist for 1-5 months after onset of the disease. Serology is not useful in this early stage.