IJCS | Volume 31, Nº2, March / April 2018

179 indicated for patients with 4-5 points (in this subgroup, there is incidence of 4.4% of stroke versus 2.0% of major bleeding per year). In the 3 point score group, stroke and major bleeding rates with OAC are equivalent, and acetylsalicylic acid (ASA) or warfarin can be indicated. 32 In 2 point patients with low incidence of stroke (1.2% per year), ASA was recommended, or no prophylaxis. Patients with 0-1 point, with incidence close to zero, would not require prophylaxis. 33 Arrhythmic manifestations CCC i s e s s e n t i a l l y a n a r r h y t hmo g e n i c cardiomyopathy, with pathophysiological peculiarities in this context, which makes it uniquely distinct from other cardiopathies. Virtually, all types of atrial and ventricular arrhythmia may occur, including sinus node dysfunction, intermittent or complete AV block and complex ventricular arrhythmias. The arrhythmias may course asymptomatic or present with non-specific malaise or sudden, fleeting and spontaneously resolved onset palpitation, at rest or by exertion. Symptoms of low cardiac output due to Stokes-Adams syndrome are less common, but more ominous, including presyncope, lipotimia, or even syncope, which can occasionally be preceded by palpitations. These episodes can either correspond to (sustained or nonsustained) ventricular tachycardia, with or without hemodynamic instability, or to bradyarrhythmias due to atrioventricular block. 34 In some cases, the standard 12-lead ECG with rhythm strip shows premature and ectopic ventricular depolarization, and even ventricular tachycardia outbreaks, in addition to atrial fibrillation or complete atrioventricularblock (AVB). Tachycardic ventricular arrhythmias and AV conduction disorders leading to periods of bradycardia can often alternate, frequently coexisting during the same Holter recording. At clinical examination, it is possible to detect fixed doubling of the second heart sound (at a pulmonary focus), irregular heart rhythm, or even bradycardia, often associated with typical signs of a-waves, periodically incremented in the jugular venous pulse and reinforcement of the first heart sound, in cannon waves, when there is a temporal correlation between atrial and ventricular systoles, which is suggestive of complete atrioventricular block. The presence and density of arrhythmia correlate with the degree of ventricular dysfunction in many cases, but can also occur in patients with preserved global left ventricular function, constituting the "isolated arrhythmogenic form” of the disease. This characteristic, which distinguishes CCC from coronary artery disease in patients with ventricular dysfunction, as well as from other cardiomyopathies, and makes T. cruzi infected patients especially susceptible to early sudden death, derives from its pathophysiological peculiarities and peculiar pathogenesis. In fact, themechanismof severe ventricular arrhythmia in CCC is mainly associatedwith the presence of regional fibrosis (especially in the posterolateral regions of the LV) and macroreentry circuits formation. 35 Recent studies using cardiac magnetic ressonance have reinforced the idea that the presence of regional fibrosis is a major factor for the arrhythmic mechanism in this disease. 36-38 Another relevant pathophysiological factor that potentially triggers severe ventricular arrhythmia and sudden death in CCC patients is regional myocardial extensive and early sympathetic denervation. In a study with patients with CCC and normal or slightly reduced LV function, the presence of sustained ventricular tachycardia has been associated with more extensive areas of viable denervated myocardium, detected through I-MIBG myocardial scintigraphy 123 . 39 Sudden Death It is estimated that sudden death is the leading cause of mortality throughout the various phases of CCC, corresponding to 55 - 65% of deaths. 22 Sudden death is often triggered by physical effort and may be caused both by severe tachyarrhythmias, such as ventricular tachycardia and fibrillation (probably in 80-90%of cases), and (less frequently) by asystole or complete AV block. 40 The detection of nonsustained and especially of sustained ventricular tachycardias increases the chance of sudden death, but it occurs mainly in patients with advanced ventricular dysfunction. Anginal manifestations Complaints of precordialgia in patients with CCC are quite common. This pain has characteristics that are often atypical for myocardial ischemia, described as stabbing, fleeting, or, conversely, long lasting (hours or even days), poorly located, usually not related to efforts, sometimes caused by emotional stress andwith recurrent patterns throughout the day. However, sometimes, the episodes may be more acute, with typically ischemic characteristics, making the diagnosis even more Simões et. al. Chagas Disease Cardiomyopathy Int J Cardiovasc Sci. 2018;31(2)173-189 Review Article