title: T-wave alternans testing in pacemaker patients: comparison of pacing modes and long-term prognostic relevance.
abstract: BACKGROUND
  T-wave alternans (TWA) is a useful method for identifying patients who are at risk for sudden cardiac death. We aimed to determine the effects of different pacing modes on test results and long-term prognostic relevance of TWA in patients following a dual-chamber (DDD) pacemaker implantation.
  
  
  METHODS
  Sixty-three patients (mean age 68 ± 13 years) with structural heart disease and recently implanted DDD pacemakers were enrolled. Left ventricular (LV) function was normal or moderately impaired (mean LV ejection fraction 61 ± 13%). All patients underwent sequential TWA testing using atrial and ventricular pacing.
  
  
  RESULTS
  During atrial pacing requiring physiologic conduction to the ventricles, 21% of TWA tests were positive, 43% negative, and 36% indeterminate. When using right ventricular (RV) pacing in the same patients, 19% of tests were positive, 40% negative, and 41% indeterminate. When positive and indeterminate tests were grouped as nonnegative, the concordance between atrial and ventricular pacing was 62% (κ= 0.22). After a mean follow-up of 5.9 ± 1.9 years, 18 (29%) patients had died. Improved survival was predicted by a negative TWA test using atrial pacing (P = 0.028), but not with ventricular pacing (P = 0.722).
  
  
  CONCLUSIONS
  In patients with dual-chamber pacemakers, there is a low concordance of TWA test results between atrial pacing with intrinsic conduction to the ventricles and apical RV pacing via pacemaker electrode. However, TWA during atrial pacing clearly exerts long-term prognostic relevance in a patient group with preserved LV function and structural heart disease.
authors.affiliation: Department of Cardiology and Pneumology, Heart Center, Georg-August-University of Göttingen, Göttingen, Germany. marc.dorenkamp@med.unigoettingen.de
authors.forename: Marc
authors.initials: M
authors.lastname: Dorenkamp
authors.forename: Christoph
authors.initials: C
authors.lastname: Breitwieser
authors.forename: Andreas J
authors.initials: AJ
authors.lastname: Morguet
authors.forename: Joachim
authors.initials: J
authors.lastname: Seegers
authors.forename: Steffen
authors.initials: S
authors.lastname: Behrens
authors.forename: Markus
authors.initials: M
authors.lastname: Zabel
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001145:Arrhythmias, Cardiac / Q000503:physiopathology; D002304:Cardiac Pacing, Artificial / Q000379:methods; D016757:Death, Sudden, Cardiac / Q000517:prevention & control*; D004562:Electrocardiography; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology; D006331:Heart Diseases / Q000401:mortality / Q000503:physiopathology* / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial; D011379:Prognosis; D011446:Prospective Studies; D012306:Risk; D013318:Stroke Volume / Q000502:physiology; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology