title: Usefulness of microvolt T-wave alternans for predicting outcome in patients with Chagas disease with implantable cardioverter defibrillators.
abstract: BACKGROUND
  Chagas disease (ChD) may lead to life-threatening heart disease, including malignant ventricular arrhythmias. The use of implantable cardioverter defibrillators (ICDs) has become the main therapeutic strategy for secondary prevention of SCD in Chagas disease (ChD). Microvolt T-wave alternans (MTWA) is a direct measure of ventricular repolarization instability and has emerged as a potentially useful way of determining arrhythmia vulnerability. However, this methodology has not been evaluated in patients with ChD.
  
  
  OBJECTIVE
  To evaluate the predictive value of MTWA testing for appropriate therapy or death in ChD patients with ICDs.
  
  
  METHODS
  This prospective study included consecutive patients who received ICD implantations in a Brazilian tertiary referral center.
  
  
  RESULTS
  Seventy-two patients were followed for a median time of 422 (range 294-642) days. Thirty-three patients had ChD. The MTWA was non-negative (positive or indeterminate) in 27 (81.8%) of ChD patients. The combined primary outcome (appropriate ICD therapy or death) occurred in 29 patients (40.3%); 17 out 33 ChD patients presented the primary outcome. There was a statistically significant difference in event-free survival between ChD patients with negative and non-negative MTWA results (p=0.02). Non-negative MTWA tests nearly triple the risk of appropriate ICD therapy or death (HR=2.7, 95% CI: 1.7-4.4, p=0.01) in patients with ChD and was the only variable associated with outcomes. The sensitivity and the negative predictive value was 100% in ChD patients.
  
  
  CONCLUSIONS
  MTWA may be useful in recognizing high-risk ICD patients who may require adjunctive therapies with antiarrhythmic drugs or catheter ablation.
authors.affiliation: Departamento de Clínica Médica, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil; Serviço de Cardiologia Cirurgia Cardiovascular, Hospital das Clínicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil. Electronic address: marcopmed@yahoo.com.
authors.forename: Marco Paulo Tomaz
authors.initials: MPT
authors.lastname: Barbosa
authors.affiliation: Departamento de Clínica Médica, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
authors.forename: Manoel Otávio
authors.initials: MO
authors.lastname: da Costa Rocha
authors.affiliation: Departamento de Clínica Médica, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
authors.forename: Elson Santos
authors.initials: ES
authors.lastname: Neto
authors.affiliation: Departamento de Clínica Médica, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
authors.forename: Fernando Vieira
authors.initials: FV
authors.lastname: Brandão
authors.affiliation: UOC Malattie Cardiovascolari, Fondazione IRCSS Ca' Granda Ospedale Maggiore Policlinico, Dipartimento di Scienze Cliniche e di Comunità, University of Milan, Italy.
authors.forename: Federico
authors.initials: F
authors.lastname: Lombardi
authors.affiliation: Departamento de Clínica Médica, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil; Serviço de Cardiologia Cirurgia Cardiovascular, Hospital das Clínicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
authors.forename: Antonio Luiz Pinho
authors.initials: ALP
authors.lastname: Ribeiro
mesh_terms: D000368:Aged; D001145:Arrhythmias, Cardiac / Q000175:diagnosis / Q000209:etiology / Q000517:prevention & control; D001938:Brazil / Q000453:epidemiology; D014355:Chagas Disease / Q000150:complications / Q000175:diagnosis / Q000401:mortality / Q000628:therapy; D016757:Death, Sudden, Cardiac / Q000517:prevention & control*; D017147:Defibrillators, Implantable; D018572:Disease-Free Survival; D004554:Electric Countershock / Q000295:instrumentation / Q000379:methods; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D018570:Risk Assessment / Q000379:methods
keywords: Chagas disease; Implantable cardioverter defibrillator; Microvolt T-wave alternans; Risk stratification; Ventricular arrhythmia