Department of Medicine, Harvard Medical School, Boston, Massachusetts 02115.
Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215; email:
Annu Rev Med. 2018 Jan 29;69:147-164. doi: 10.1146/annurev-med-041316-090046.
Sudden cardiac death (SCD) accounts for ∼50% of mortality after myocardial infarction (MI). Most SCDs result from ventricular tachyarrhythmias, and the tachycardias that precipitate cardiac arrest result from multiple mechanisms. As a result, it is highly unlikely that any single test will identify all patients at risk for SCD. Current guidelines for use of implantable cardioverter-defibrillators (ICDs) to prevent SCD are based primarily on measurement of left ventricular ejection fraction (LVEF). Although reduced LVEF is associated with increased total cardiac mortality after MI, the focus of current guidelines on LVEF omits ∼50% of patients who die suddenly. In addition, there is no evidence of a mechanistic link between reduced LVEF and arrhythmias. Thus, LVEF is neither sensitive nor specific as a tool for post-MI risk stratification. Newer tests to screen for predisposition to ventricular arrhythmias and SCD examine abnormalities of ventricular repolarization, autonomic nervous system function, and electrical heterogeneity. These tests, as well as older methods such as programmed stimulation, the signal-averaged electrocardiogram, and spontaneous ventricular ectopy, do not perform well in patients with LVEF ≤30%. Recent observational studies suggest, however, that these tests may have greater utility in patients with LVEF >30%. Because SCD results from multiple mechanisms, it is likely that combinations of risk factors will prove more precise for risk stratification. Prospective trials that evaluate the performance of risk stratification schema to determine ICD use are necessary for cost-effective reduction of the incidence of SCD after MI.
心脏性猝死（SCD）占心肌梗死（MI）后死亡率的约 50%。大多数 SCD 是由室性心动过速引起的，导致心脏骤停的心动过速是由多种机制引起的。因此，几乎不可能有任何单一的测试能够识别所有有 SCD 风险的患者。目前，使用植入式心脏复律除颤器（ICD）预防 SCD 的指南主要基于左心室射血分数（LVEF）的测量。虽然 LVEF 降低与 MI 后总心脏死亡率增加相关，但当前指南对 LVEF 的关注忽略了约 50%的突然死亡患者。此外，LVEF 降低与心律失常之间没有明确的机制联系。因此，LVEF 既不敏感也不特异，不能作为 MI 后风险分层的工具。用于筛查室性心律失常和 SCD 易感性的新测试检查心室复极、自主神经系统功能和电异质性的异常。这些测试，以及较旧的方法，如程控刺激、信号平均心电图和自发性室性早搏，在 LVEF ≤30%的患者中表现不佳。然而，最近的观察性研究表明，这些测试在 LVEF >30%的患者中可能具有更大的用途。由于 SCD 是由多种机制引起的，因此多种危险因素的组合可能更能准确地进行风险分层。评估风险分层方案以确定 ICD 使用的前瞻性试验对于 MI 后降低 SCD 的发生率具有成本效益是必要的。
