Objectives: 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) ≤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).
Bibliographical noteFunding Information:
This study was sponsored by Medtronic, Inc. Dr. Chow has received honoraria from Biotronik, Cambridge Heart, Medtronic, Inc., and St. Jude Medical, and has ownership interest in Medtronic, Inc. Dr. Onufer has received honoraria from St. Jude Medical. Mr. Peterson is employed by Medtronic, Inc. Dr. Brown has ownership interest in and is employed by Medtronic, Inc. Dr. Pu has ownership interest in and is employed by Medtronic, Inc. Dr. Benditt has ownership interest in, has received honoraria from, and is on the consultant/advisory board for Medtronic, Inc. and St. Jude Medical.
- T-wave alternans
- defibrillator therapy
- risk stratification
- sudden death
- ventricular arrhythmias