title: Ability of microvolt T-wave alternans to modify risk assessment of ventricular tachyarrhythmic events: a meta-analysis.
abstract: BACKGROUND
  Prior studies have indicated that the magnitude of risk association of microvolt T-wave alternans (MTWA) testing appears to vary with the population studied. We performed a meta-analysis to determine the ability of MTWA to modify risk assessment of ventricular tachyarrhythmic events (VTEs) and sudden cardiac death (SCD) across a series of patient risk profiles using likelihood ratio (LR) testing, a measure of test performance independent of disease prevalence.
  
  
  METHODS
  We identified original research articles published from January 1990 to January 2011 that investigate spectrally derived MTWA. Ventricular tachyarrhythmic event was defined as the total and arrhythmic mortality and nonfatal sustained or implantable cardioverter-defibrillator-treated ventricular tachyarrhythmias. Summary estimates were created for positive and nonnegative MTWA results using a random-effects model and were expressed as positive (LR+) and negative (LR-) LRs.
  
  
  RESULTS
  Of 1,534 articles, 20 prospective cohort studies met our inclusion criteria, consisting of 5,945 subjects predominantly with prior myocardial infarction or left ventricular dysfunction. Although there was a modest association between positive MTWA and VTE (relative risk 2.45, 1.58-3.79) and nonnegative MTWA and VTE (3.68, 2.23-6.07), test performance was poor (positive MTWA: LR+ 1.78, LR- 0.43; nonnegative MTWA: LR+ 1.38, LR- 0.56). Subgroup analyses of subjects classified as prior VTE, post-myocardial infarction, SCD-HeFT type, and MADIT-II type had a similar poor test performance. A negative MTWA result would decrease the annualized risk of VTE from 8.85% to 6.37% in MADIT-II-type patients and from 5.91% to 2.60% in SCD-HeFT-type patients.
  
  
  CONCLUSIONS
  Despite a modest association, results of spectrally derived MTWA testing do not sufficiently modify the risk of VTE to change clinical decisions.
authors.affiliation: Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: Anurag
authors.initials: A
authors.lastname: Gupta
authors.forename: Donald D
authors.initials: DD
authors.lastname: Hoang
authors.forename: Leah
authors.initials: L
authors.lastname: Karliner
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Tice
authors.forename: Paul
authors.initials: P
authors.lastname: Heidenreich
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Wang
authors.forename: Mintu P
authors.initials: MP
authors.lastname: Turakhia
mesh_terms: D016757:Death, Sudden, Cardiac / Q000453:epidemiology*; D004562:Electrocardiography; D006352:Heart Ventricles / Q000503:physiopathology*; D006801:Humans; D015994:Incidence; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology; D014481:United States / Q000453:epidemiology