IJCS | Volume 31, Nº2, March / April 2018

175 Chart 1 – Clinical classification of left ventricular dysfunction in Chagas’ heart disease (apud Andrade J et alii) Acute phase Chronic phase Indeterminate form Cardiac formwith no ventricular dysfunction Cardiac form with ventricular dysfunction A B1 B2 C D Patients with findings compatible with acute Chagas disease Patients at risk for developing CHF. They have positeve serology, neither structural cardiopathy nor CHF symptoms. No digestive changes Patients with structural cardiopathy, evidenced by electrocardiographic or echocardiographic changes, but with normal global ventricular function and neither current nor previous signs and symptoms of CHF Patients with structural cardiopathy characterized by global ventricular dysfunction, and neither current nor previous signs and symptoms of CHF Patients with ventricular dysfunction and current or previous symptoms of CHF (NYHA FC I, II, III or IV) Patients with refractory symptoms of CHF at rest, despite optimized clinical treatment, requiring specialized interventions With remission of the parasitemia and systemic inflammatory reactions, the patient enters the chronic phase of the disease, inwhich it is believed that, a process of low-intensity, but incessant, focal myocarditis occurs since the indeterminate form, which causes progressive destruction of fibers and restorative myocardial fibrosis. This causes cumulative myocardial damage, and results in a picture of late dilated cardiomyopathy, usually accompanied by severe arrhythmias, thromboembolic complications and sudden death in a high proportion of cases. It is believed that chronic myocarditis in Chagas' disease is due to two main pathogenetic processes: myocardial damage associated directly with inflammation caused by parasitized cardiac fibers, with multiple but low-intensity outbreaks; and myocardial aggression caused by adverse immune reaction directed, and continuously fed, by the reiterated presentation of antigens linked to persistent cardiac parasitism. In addition, there is evidence to support the idea that there are still two auxiliary and amplifyingmechanisms of themyocardial injury: myocardial perfusiondisorders due to thepresenceof abnormalities incoronarymicrocirculation and autonomic cardiac innervation (Figure 2). 11 Acute phase Signs and Symptoms The acutephasebegins after an incubationperiodusually of 1-4 week after exposure to T. cruzi . The lesions known as “chagomas”, including the typical, but non-specific, Romaña’s sign, are a result of mucosal or cutaneous edema at the site of inoculation. Most patients present asymptomatic or showsystemic infection symptoms (fever, hepatosplenomegaly, diaphoresis, m yalgia), accompanied by equally non-specific laboratory alterations, especially leukocytosis, with absolute lymphocytosis. A minority of patients present a clinical picture of myocarditis, with signs and symptoms similar tomyocarditis of other causes: dyspnea, fatigue and other commemorative symptoms of heart failure. In these cases, the ECG may show sinus tachycardia, ventricular ectopic beats, low voltage of the QRS complexes, branch block, diffuse disturbances of ventricular repolarization, first-degree or more advanced AV block. Chest x-ray may show increased cardiothoracic ratio in more severe cases, which may be associated with increased heart chambers and/or pericardial effusion. The echocardiogram often shows pericardial effusion, segmental changes in parietal mobility and insufficiency of mitral and tricuspid valves and, less frequently, cavitary dilation and decreased global systolic performance. These abnormalities usually resolve in the majority of patients over the first year of follow-up. 12,13 Diagnosis Serological tests are usually negative in the first weeks of infection. The diagnosis is made by detection of circulating parasites or their genetic material (PCR) through a variety of methods, such as blood culture, direct visualization of the parasite in peripheral blood, Simões et. al. Chagas Disease Cardiomyopathy Int J Cardiovasc Sci. 2018;31(2)173-189 Review Article