To the Editor The article by Juo et al¹ addresses the important issue of temporal trends in perioperative myocardial infarction after high-risk vascular surgery. We congratulate the authors on their contribution; however, we have some reservations concerning the methods of this study.

Definitions of myocardial infarction used in the database are out of date in light of recent developments in perioperative cardiac monitoring. The diagnostic threshold for myocardial infarction in the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) cohort was defined as new elevation in troponin values greater than 3 times the upper level of the reference range. Furthermore, troponin levels were not measured routinely but only when the clinicians suspected ischemia. The problem with this approach is that 65% of perioperative myocardial infarctions are asymptomatic.²

致编辑Juo 等人¹的文章探讨了高危血管手术后围手术期心肌梗死的时间趋势这一重要问题。我们祝贺作者的贡献；但是，我们对这项研究的方法有一些保留。

鉴于围手术期心脏监测的最新发展，数据库中使用的心肌梗死定义已经过时。美国外科医师学会国家手术质量改进计划 (NSQIP) 队列中心肌梗死的诊断阈值定义为肌钙蛋白值的新升高超过参考范围上限的 3 倍。此外，肌钙蛋白水平没有常规测量，只有在临床医生怀疑缺血时才测量。这种方法的问题是 65% 的围手术期心肌梗死是无症状的。²