Does microvolt T-wave alternans testing predict ventricular tachyarrhythmias in patients with ischemic cardiomyopathy and prophylactic defibrillators? The MASTER (Microvolt T Wave Alternans Testing for Risk Stratification of Post-Myocardial Infarction Patients) trial.
OBJECTIVE
The purpose of this trial was to determine whether microvolt T-wave alternans (MTWA) predicts ventricular tachyarrhythmic events (VTEs) in post-myocardial infarction patients with left ventricular ejection fraction (LVEF) < or =30%.


BACKGROUND
Previous studies have established MTWA as a predictor for total and arrhythmic mortality, but its ability to identify prophylactic implantable cardioverter-defibrillator (ICD) recipients most likely to experience VTEs remains uncertain.


METHODS
This prospective trial was conducted at 50 U.S. centers. Patients were eligible if they met MADIT-II (Multicenter Automatic Defibrillator Implantation Trial II) indications for device implant. All patients underwent MTWA testing followed by ICD implantation, with pre-specified programming to minimize the likelihood of therapies for non-life-threatening VTE. Minimum follow-up was 2 years with annual MTWA testing. Initially indeterminate MTWA tests were repeated.


RESULTS
Analyses were conducted on 575 patients (84% male; average age +/- SD = 65 +/- 11 years; average LVEF +/- SD = 0.24 +/- 0.05). The final distribution of MTWA results were: MTWA positive in 293 (51%), MTWA negative in 214 (37%), and indeterminate in 68 patients (12%). Over an average follow-up of 2.1 +/- 0.9 years, there were 70 VTEs. A VTE occurred in 48 of 361 (13%, 6.3%/year) MTWA non-negative and 22 of 214 (10%, 5.0%/year) MTWA negative patients. A non-negative MTWA test result was not associated with VTE (hazard ratio: 1.26; 95% confidence interval: 0.76 to 2.09; p = 0.37), although total mortality was significantly increased (hazard ratio: 2.04; 95% confidence interval: 1.10 to 3.78; p = 0.02).


CONCLUSIONS
In MADIT-II-indicated ICD-treated patients, the risk of VTE does not differ according to MTWA classification, despite differences in total mortality. (MASTER I-Microvolt T Wave Alternans Testing for Risk Stratification of Post MI Patients; NCT00305240).
Chow
Theodore
T
Lindner Clinical Trial Center at The Christ Hospital, Cincinnati, Ohio 45219, USA. Chowt@ohioheart.org
Kereiakes
Dean J
DJ
Onufer
John
J
Woelfel
Alan
A
Gursoy
Sinan
S
Peterson
Brett J
BJ
Brown
Mark L
ML
Pu
Wenji
W
Benditt
David G
DG
D000368:Aged; D009202:Cardiomyopathies / Q000150:complications* / Q000175:diagnosis / Q000628:therapy; D017147:Defibrillators, Implantable; D005260:Female; D006334:Heart Function Tests; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000150:complications* / Q000175:diagnosis / Q000628:therapy; D011446:Prospective Studies; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000209:etiology* / Q000517:prevention & control