IJCS | Volume 31, Nº2, March / April 2018

176 Low-grade chronic T. cruzi infection Continuous antigen presentation Cross-reactive humoral and cellular immune response Autoimmune aggression Platelet agrregation, Thrombosis, endothelial dysfunction Nervous Tissue damage Autonomic denervation Impaired hemeometric regulation Hemodynamic overload LV dilation and remodeling Myocardial ischemia Microvascular Derangement Damaged cardiac fibers Cardiac dilation and failure Figure 2 – Scheme showing the relationship between etiopathogenic mechanisms in chronic chagasic myocarditis. A) main mechanisms B) auxiliary and amplifying mechanisms of the myocardial injury. Adapted from Marin-Neto et alii. Circulation. 2007;115(9):1109-23. xenodiagnosis, or the presence of parasite nests in amastigote form revealed by biopsy with histopathology of affected organs, or of cutaneous “chagomas”. Endomyocardial biopsy is rarely used for the diagnosis, but may be necessary, especially in cases of suspected reactivation of Chagas disease after heart transplantation, inwhich a clear distinction from implant rejection is critical in patient management. 14 Clinical Course The clinical course of the acutephase inChagas disease is often benign and the signs and symptoms typically resolve spontaneously over 1 to 3 months. It is estimated that fatal evolutionoccurs in<5%of patients in the acutephase,when contaminated through classic vectorial transmission (via the bite of a triatomine bug), predominantly in patients with refractory heart failure. However, in acute cases resulting from contamination by the oral route (for example after ingestion of T cruzi contaminated sugar cane juice or açai), the acute disease is usually more severe and the rates of mortality are higher. This is probably due to inoculation of high parasite load and ease of penetration through the gastrointestinal mucosa, which is highly permeable to the parasite, in these cases. Treatment The treatment of clinical manifestations of myocarditis and heart failure is similar to the one recommended for cases ofmyocarditis of other etiologies, including intensive measures of circulatory support in more severe cases. However, more specifically, although there is no conclusive evidence concerning possible clinically relevant benefits that could be achieved, antiparasitic treatment with benznidazole or nifurtimox is indicated for all cases of acute Chagas disease, independently of the infection route or the reactivation mechanism, since it may decrease the severity of the symptoms, reduce disease time and the duration of detectable parasitemia. The occurrence of parasitological cure, besides clinical cure, is estimated in 60 to 85% of cases. 15,16 Simões et. al. Chagas Disease Cardiomyopathy Int J Cardiovasc Sci. 2018;31(2)173-189 Review Article