title: Prognostic value of signal-averaged electrocardiogram in Chagas disease.
abstract: BACKGROUND
  The value of signal-averaged ECG (SAECG) in the risk stratification of Chagas disease (ChD), a potentially lethal illness prevalent in Latin America, remains controversial. The aim of this prospective longitudinal study was to determine the prognostic value of SAECG in ChD, using multivariate models with other established prognostic predictors, and to develop a simple prediction risk score.
  
  
  METHODS
  The study enrolled 184 ambulatory ChD patients (107 men; age: 48 +/- 12 years) in sinus rhythm and without other systemic diseases. All patients underwent comprehensive evaluation that included clinical examination, ECG, chest X-ray, 24-hour Holter monitoring, echocardiogram, stress testing, and time domain SAECG. Individual medical therapy was adjusted according to a standardized treatment regimen. The association of potential risk factors obtained by noninvasive evaluation and death was tested by Cox proportional-hazards analysis.
  
  
  RESULTS
  During mean follow-up time of 74 +/- 17 months, 13 patients died. Three independent prognostic factors were identified: left ventricular ejection fraction <50% (HR = 5.2, P = 0.048), ventricular tachycardia at either Holter monitoring or stress testing (HR = 9.9, P = 0.036), and prolonged (>150 ms) filtered QRS complex (HR = 4.3, P = 0.035). A prognostic score developed considering the number of risk factors of each patient had an excellent performance in predicting death (c statistic: 0.92).
  
  
  CONCLUSIONS
  Prolonged filtered QRS duration obtained by SAECG is an independent predictor of death in ChD. A prediction score including three risk factors, depressed left ventricular ejection fraction, ventricular tachycardia and prolonged filtered QRS complex, has shown to be useful for stratifying risk categories in ChD.
authors.affiliation: Post-graduate Course of Tropical Medicine, School of Medicine, Hospital das Clínicas, Federal University of Minas Gerais, Belo Horizonte, Brazil. tom@hc.ufmg.br
authors.forename: Antonio Luiz Pinho
authors.initials: AL
authors.lastname: Ribeiro
authors.forename: Paulo Sérgio
authors.initials: PS
authors.lastname: Cavalvanti
authors.forename: Federico
authors.initials: F
authors.lastname: Lombardi
authors.forename: Maria do Carmo Pereira
authors.initials: Mdo C
authors.lastname: Nunes
authors.forename: Márcio Vinícius Lins
authors.initials: MV
authors.lastname: Barros
authors.forename: Manoel Otávio da Costa
authors.initials: MO
authors.lastname: Rocha
mesh_terms: D000328:Adult; D000368:Aged; D002598:Chagas Cardiomyopathy / Q000175:diagnosis* / Q000401:mortality*; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D004562:Electrocardiography / Q000379:methods* / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D015994:Incidence; D007558:Italy / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care / Q000379:methods* / Q000706:statistics & numerical data; D011379:Prognosis; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D012680:Sensitivity and Specificity; D016019:Survival Analysis; D015996:Survival Rate