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.

问题：微伏T波电交替（MTWA）是心肌梗死后危险分层的可靠方法吗？

方法：MASTER研究是一项前瞻性、多中心试验，575例心肌梗死后射血分数（EF）≤30% （平均EF为24%）的患者（平均年龄65岁）在植入埋藏式心律转复除颤器（ICD）之前行MTWA试验。MTWA试验被分为阴性和非阴性（阳性或不确定性）。随访时间为2～4年，主要终点为室性心动过速事件（VTE），定义为心源性猝死或适当的ICD放电。

结果：MTWA试验在63%患者中为非阴性，在37%患者中为阴性。一年VTE发生率在非阴性和阴性试验患者中（分别为6.3%和5.0%）没有显著差异。MTWA不是VTE的预测因素。总死亡率在MTWA试验非阴性患者中比阴性患者高2倍。

结论：MTWA试验不能从有缺血性心肌病的心肌梗死后患者中，准确筛选出致死性心律失常的低危患者。

评论：此研究中ICD的植入符合MADIT-II标准。之前的回顾性研究提示MTWA试验阴性表明患者发生致死性心律失常的风险极低，按照MADIT-II标准的ICD备选者不需要植入ICD。如果真是这样，将会显著改善心肌梗死后预防性植入ICD的性价比。然而，这项研究表明，MTWA试验阴性并不意味着植入ICD对于改善MADIT-II型患者的预后无效。

出处：J Am Coll Cardiol 2008;52:1607-1615.