title: Profile of microvolt T-wave alternans testing in 1003 patients hospitalized with heart failure.
abstract: OBJECTIVE
  Observational studies in selected populations have suggested that microvolt T-wave alternans (MTWA) testing may identify patients with heart failure (HF) at risk of sudden cardiac death. The aims of this study were to investigate the utility of MTWA testing in an unselected population of patients with HF and to evaluate the clinical characteristics associated with the MTWA results.
  
  
  RESULTS
  A total of 1003 patients hospitalized with decompensated HF were enrolled. MTWA testing was planned 1 month post-discharge; 648 patients returned for MTWA testing. Mean age was 70.8 ± 10.6 years and 58% were male. Of these patients who returned, 318 (49%) were ineligible for MTWA testing due to atrial fibrillation (AF), pacemaker dependency, or physical inability to undertake the test. Of the MTWA tests, 100 (30%) were positive, 78 (24%) were negative, and 152 (46%) were indeterminate; 112/152 indeterminate tests (74%) occurred because of failure to achieve target heart rate (HR) due to chronotropic incompetence or physical limitations. There were differences in patient characteristics according to MTWA result. Independent predictors of a negative result included younger age and higher left ventricular ejection fraction (LVEF). Independent predictors of a positive result included higher HR during MTWA testing and lower LVEF. Independent predictors of an indeterminate result included older age and history of previous/paroxysmal AF.
  
  
  CONCLUSIONS
  Only half of patients with HF are eligible for MTWA testing and the most common result is an indeterminate test. Patients with positive and indeterminate tests have different clinical characteristics. MTWA treadmill testing is not widely applicable in typical HF patients and is unlikely to refine risk stratification for sudden death on a population level.
authors.affiliation: British Heart Foundation Cardiovascular Research Centre, University of Glasgow, 126 University Place, Glasgow, UK.
authors.forename: Colette E
authors.initials: CE
authors.lastname: Jackson
authors.forename: Rachel C
authors.initials: RC
authors.lastname: Myles
authors.forename: Ioannis K
authors.initials: IK
authors.lastname: Tsorlalis
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Dalzell
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Spooner
authors.forename: John R
authors.initials: JR
authors.lastname: Rodgers
authors.forename: Vladimir
authors.initials: V
authors.lastname: Bezlyak
authors.forename: Nicola
authors.initials: N
authors.lastname: Greenlaw
authors.forename: Ian
authors.initials: I
authors.lastname: Ford
authors.forename: Stuart M
authors.initials: SM
authors.lastname: Cobbe
authors.forename: Mark C
authors.initials: MC
authors.lastname: Petrie
authors.forename: John J V
authors.initials: JJ
authors.lastname: McMurray
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D001145:Arrhythmias, Cardiac / Q000473:pathology*; D016009:Chi-Square Distribution; D017147:Defibrillators, Implantable; D005080:Exercise Test; D005260:Female; D006333:Heart Failure / Q000473:pathology*; D006801:Humans; D008297:Male; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D018570:Risk Assessment / Q000379:methods; D013318:Stroke Volume; D016277:Ventricular Function, Left