title: Microvolt T-wave alternans for the risk stratification of dangerous ventricular arrhythmias in patients with previously implanted automatic cardioverter-defibrillator.
abstract: BACKGROUND
  Sudden cardiac death (SCD) is the main cause of death in patients with reduced left ventricular ejection fraction (LVEF). Implantation of an automatic cardioverter-defibrillator (ICD) significantly reduces mortality of these patients. T-wave alternans (TWA) analysis is a relatively new method of SCD risk stratification. However, it's prognostic role in patients with ICD has not yet been fully established.
  
  
  OBJECTIVE
  To assess the predictive value of TWA in patients with previously implanted ICD.
  
  
  METHODS
  The study included 67 patients with properly functioning ICD (54 men and 13 women, aged 62.2 ± 8.4 years). All patients underwent TWA analysis on the treadmill using the Cambridge Heart 2000 system. Results were considered as positive, negative or indeterminate. Each patient had at least 1 clinical control visit with ICD interrogation during the 12 ± ± 6 months of follow-up. The recurrence of sustained ventricular arrhythmias: ventricular tachycardia (VT) or ventricular fibrillation (VF) was analysed.
  
  
  RESULTS
  No significant relationship was found between previous infarction (p = 0.810), aetiology (p = 0.768), LVEF (p = 0.413) or age (p = 0.562) and the incidence of arrhythmia during follow-up. The results of TWA were not significantly different between patients with or without VT or VF. The TWA analysis identified patients with arrhythmia recurrences with a sensitivity of 62%, specificity of 49%, negative predictive value of 81%, and positive predictive value of 28%. The TWA performance was better in patients with non-ischaemic than ischaemic cardiomyopathy (negative predictive value: 100%, positive predictive value: 75%).
  
  
  CONCLUSIONS
  The TWA alternans was moderately effective for identification of patients with ICD and ventricular arrhythmia recurrences. The test was most useful for identification of patients with non-ischaemic cardiomyopathy who are of low arrhythmic risk.
authors.affiliation: Department of Cardiology, Pomeranian Medical University, Szczecin, Poland.
authors.forename: Maciej
authors.initials: M
authors.lastname: Lewandowski
authors.forename: Irmina
authors.initials: I
authors.lastname: Kossuth
authors.forename: Joanna
authors.initials: J
authors.lastname: Zielonka
authors.forename: Maciej
authors.initials: M
authors.lastname: Wielusiński
authors.forename: Arkadiusz
authors.initials: A
authors.lastname: Kazimierczak
authors.forename: Zdzisława
authors.initials: Z
authors.lastname: Kornacewicz Jach
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Przybycień
authors.forename: Robert
authors.initials: R
authors.lastname: Kaliszczak
mesh_terms: D000368:Aged; D001145:Arrhythmias, Cardiac / Q000517:prevention & control*; D016757:Death, Sudden, Cardiac / Q000517:prevention & control*; D017147:Defibrillators, Implantable; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012008:Recurrence; D018570:Risk Assessment; D012680:Sensitivity and Specificity