ABC | Volume 110, Nº5, May 2018

Original Article Association between Microvolt T-Wave Alternans and Malignant Ventricular Arrhythmias in Chagas Disease Bárbara Carolina Silva Almeida, 1 André Assis Lopes do Carmo, 1 Marco Paulo Tomaz Barbosa, 1 José Luiz Padilha da Silva, 2 Antonio Luiz Pinho Ribeiro 1 Hospital das Clínicas e Faculdade de Medicina da Universidade Federal de Minas Gerais, 1 Belo Horizonte, MG - Brazil Departamento de Estatística, Universidade Federal do Paraná, 2 Curitiba, PR - Brazil Mailing Address: Bárbara Carolina Silva Almeida • Rua Ceará, 1620. Apto 1001. Postal Code 30150-311, Funcionários, Belo Horizonte, MG – Brazil E-mail: barbaracsalmeida@gmail.com Manuscript received July 27, 2017, revised manuscript October 10, 2017, accepted October 18, 2017 DOI: 10.5935/abc.20180056 Abstract Background: Sudden cardiac death is the most frequent death mechanism in Chagas disease, responsible for 55% to 65% of the deaths of patients with chronic Chagas cardiomyopathy (CCC). The most often involved electrophysiological mechanisms are ventricular tachycardia and ventricular fibrillation. The implantable cardioverter defibrillator (ICD) has a beneficial role in preventing sudden death due to malignant ventricular arrhythmias, and, thus the correct identification of patients at risk is required. The association of microvolt T-wave alternans (MTWA) with the appearance of ventricular arrhythmias has been assessed in different heart diseases. The role of MTWA is mostly unknown in patients with CCC. Objectives: To evaluate the association between MTWA and the occurrence of malignant ventricular arrhythmias in patients with CCC. Method: This is a case-control study including patients with CCC and ICD, with history of malignant ventricular arrhythmias (case group), and patients with CCC and no history of those arrhythmias (control group). The MTWA test results were classified as negative and non-negative (positive and indeterminate). The significance level adopted was α = 0.05. Results: We recruited 96 patients, 45 cases (46.8%) and 51 controls (53.1%). The MTWA test was non-negative in 36/45 cases (80%) and 15/51 controls (29.4%) [OR = 9.60 (95%CI: 3.41 – 27.93)]. After adjustment for known confounding factors in a logistic regression model, the non‑negative result continued to be associated with malignant ventricular arrhythmias [OR = 5.17 (95%CI: 1.05 – 25.51)]. Conclusion: Patients with CCC and history of malignant ventricular arrhythmias more often have a non–negative MTWA test as compared to patients with no history of arrhythmia. (Arq Bras Cardiol. 2018; 110(5):412-417) Keywords: Chagas Disease; Chagas Cardiomyopathy; Arrhythmias, Cardiac/complications; Defibrillators,Implantable; Death, Sudden, Cardiac. Introduction Chagas disease remains a challenge of great importance in Brazil and Latin America, and is an emerging concern in North America and European countries. 1 It is considered to be endemic in 21 countries, infects 6 to 7 million people worldwide,² accounting for the death of around 12,000 patients per year.³ Chronic Chagas cardiomyopathy (CCC) is the most important presentation of Chagas disease, because of its high frequency, severity and great impact on morbidity and mortality. Chronic Chagas cardiomyopathy has a wide range of manifestations, such as heart failure, conduction blocks, thromboembolic events and sudden death. 4,5 Sudden death is the most common mechanism of death of those patients, occurs in the presence or absence of advanced heart disease, and can be the first manifestation of the disease. The electrophysiological mechanisms most frequently involved are the ventricular arrhythmias: sustained ventricular tachycardia and ventricular fibrillation. 4,6 Implantable cardioverter-defibrillator (ICD) has a great impact on the prevention of sudden death due to malignant ventricular arrhythmias. 7,8 The use of the ICD in secondary prevention is well accepted in CCC, despite the lack of large studies, based on the results obtained from other populations. 7,9 However, its use in primary prevention is still controversial because of the high cost, intrinsic risks in implantation, and adverse effects. 10,11 Therefore, identifying patients with CCC at risk for sudden death due to malignant ventricular arrhythmias is necessary. The microvolt T-wave alternans (MTWA) test is a non‑invasive test associated with the appearance of ventricular tachyarrhythmias assessed in different clinical conditions with a high negative predictive value to identify patients at risk. 12-17 That test recognizes fluctuations of the T-wave morphology and amplitude beat to beat, measured in microvolts. Those fluctuations reflect space-temporal 412