title: Enhanced detection of arrhythmia vulnerability using T wave alternans, left ventricular ejection fraction, and programmed ventricular stimulation: a prospective study in subjects with chronic ischemic heart disease.
abstract: BACKGROUND
  In previous studies, the prognostic value of T wave alternans (TWA) was similar to that of programmed ventricular stimulation (PVS). However, presently it is unclear if TWA and PVS identify the same patients or provide complementary risk stratification information. In addition, the effects of left ventricular ejection fraction (LVEF) on the prognostic value of TWA are unknown. The aim of this study was to determine if combined assessment of TWA, LVEF, and PVS improves arrhythmia risk stratification.
  
  
  RESULTS
  This was a prospective study of 144 patients with coronary artery disease and LVEF < or =40% who were referred for PVS for standard clinical indications. The endpoint was the combined incidence of death, sustained ventricular arrhythmias, and appropriate implantable cardioverter defibrillator (ICD) therapy. TWA (hazard ratio 2.2, P = 0.03) and PVS (hazard ratio 1.9, P = 0.05) both were significant predictors of endpoint events, and TWA was the only independent predictor. LVEF markedly influenced the prognostic value of TWA, which was a potent predictor of events in subjects with LVEF between 30% and 40% (event rates: TWA+ 36%, TWA- 0%, P = 0.001) but did not predict events in subjects with LVEF <30% (hazard ratio 1.1, P > 0.5). PVS successfully identified additional low-risk patients within the cohort with negative or indeterminate TWA results (hazard ratio 4.7, P = 0.015) but did not provide incremental prognostic information for TWA+ patients (hazard ratio 0.9, P > 0.5).
  
  
  CONCLUSIONS
  The combined use of TWA, LVEF, and PVS is a promising new approach to arrhythmia risk stratification that permits identification of high-risk and very-low-risk patients.
authors.affiliation: Division of Cardiology, Department of Medicine, University of Maryland at Baltimore, Baltimore, Maryland 21201, USA. erashba@medicine.umaryland.edu
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Rashba
authors.forename: Ahmed F
authors.initials: AF
authors.lastname: Osman
authors.forename: Karen
authors.initials: K
authors.lastname: Macmurdy
authors.forename: Malcolm M
authors.initials: MM
authors.lastname: Kirk
authors.forename: Samantha E
authors.initials: SE
authors.lastname: Sarang
authors.forename: Robert W
authors.initials: RW
authors.lastname: Peters
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Shorofsky
authors.forename: Michael R
authors.initials: MR
authors.lastname: Gold
mesh_terms: D000368:Aged; D001145:Arrhythmias, Cardiac / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology* / Q000628:therapy; D002908:Chronic Disease; D017147:Defibrillators, Implantable; D018572:Disease-Free Survival; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D023381:Endpoint Determination; D005260:Female; D005500:Follow-Up Studies; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008396:Maryland; D008875:Middle Aged; D015999:Multivariate Analysis; D017202:Myocardial Ischemia / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology / Q000628:therapy; D011183:Postoperative Complications / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D012307:Risk Factors; D013318:Stroke Volume / Q000502:physiology*; D016896:Treatment Outcome; D016277:Ventricular Function, Left / Q000502:physiology*