IJCS | Volume 31, Nº2, March / April 2018

177 Chronic phase Indeterminate form The indeterminate form of the disease is classically defined as the clinical situation of an individual with parasitological and/or serological evidence of chronic T. cruzi infection, but without symptoms or physical signs of the disease, with normal ECG and chest X-ray and without digestive tract (esophagus and colon) impairment seen in radiological exams. However, more accurate complementary exams (i.e. echocardiography, nuclear angiocardiography, hemodynamic study and autonomic cardiac assessment) may demonstrate - usually subtle and of no prognostic relevance - cardiac alterations in this group of patients classifiedas indeterminate by classical criteria. 17-19 In spite of these minor abnormalities verified in many patients, those classified as indeterminate by the classical criteria, while maintaining their normal ECG status, present excellent prognosis and mortality rates comparable to those of the control group of the same age without T. cruzi . 4,20,21 Guidelines for monitoring chagasic patients in the indeterminate form There are no formal guidelines in relation to the conduction of exams for early detection of left ventricular dysfunction in patients with the indeterminate form of Chagas disease. On the other hand, there are no identifiable factors in this phase that can distinguish the individuals who will develop the clinical cardiopathy from those who will remain asymptomatic during their whole lives, just keeping the serological positivity. It is suggested that the ECG be repeated every 1 or 2 years and a simple chest X-ray every 3 or 5 years. Though it is more controversial, one may also suggest that the transthoracic echocardiography can be performed initially, and later on at regular intervals as well, every 3 to 5 years. 8,17,22,23 Cardiac Chronic Form Asymptomatic condition in Chronic Chagas' disease cardiomyopathy The absence of symptoms ismostmarked in individuals who are in incipient stages of the chronic disease, when (discrete) myocardial injury can be detected only due to alterations in complementary exams, such as ECG conduction disturbance, changes in LV segmental parietal mobility on ECG or Holter arrhythmias. In these individuals, however, sudden death may occur due to arrhythmic events, as evidenced by studies demonstrating a worsen prognosis in individuals with alterations in the ECG, evenwhen asymptomatic. 24 In a 10-year cohort study of 885 seropositive individuals, it was shown that T. cruzi infected individuals with normal ECG had a survival of 97.4%, comparable to the survival of seronegative individuals. On the other hand, survival of those with abnormal ECG was 61.3%, with a nine-fold increased risk in this group. 25 It is estimated that 2 to 5% of patients without any apparent cardiopathywill develop newECG alterations and evidence of cardiopathy each year. 19,26,27 Clinical manifestations The symptoms and physical signs present in the chronic phase of the Chagas disease cardiomyopathy are a result of four essential syndromes that can often coexist in the same patient: heart failure, arrhythmias, thromboembolism and anginal manifestations. Heart Failure Syndrome The clinical pictureofCCCwithventriculardysfunction is described in a quite uniformmanner in several literature reports, following the pioneering remarks of Chagas and Villela. 28 In the early stages of manifestation, the most frequent symptoms are fatigue and dyspnea on exertion, but the registry of more intense symptoms of pulmonary congestion, such as paroxysmal nocturnal dyspnea and decubitus with orthopnea, are uncommon. In the disease evolution, there occur the symptoms of systemic venous congestion (jugular swelling, hepatomegaly, lower limb edema and ascites) and the evolution can still progress to anasarca, adynamia, or cardiac cachexia, similar to what happens in other cardiopathies with advanced ventricular dysfunction. At clinical examination, there are also signs of cardiomegaly resulting from deviation of the ictus cordis , there may be a muffled S1 heart sound in the mitral area, fixed doubling of second heart sound due to RBBB, third heart sound and atrioventricular valve regurgitation murmur, which may occur secondarily to the dilation of ventricular chambers. Signs of low systemic output may occur in advanced cases, such as filiform pulse, slow and oliguria peripheral perfusion. These signs are common to other clinical syndromes of heart failure. In contrast to these similarities, in heart failure of Chagasic etiology, pulmonary congestion is Simões et. al. Chagas Disease Cardiomyopathy Int J Cardiovasc Sci. 2018;31(2)173-189 Review Article