Somberg J C, Tepper D
Am Heart J. 1986 Oct;112(4):808-13. doi: 10.1016/0002-8703(86)90478-3.
PVCs (trigger mechanisms) and the vulnerability of the myocardium to sustain a life-threatening ventricular tachycardia (substrate) are two variables in the sudden death equation. Physicians treating patients at risk for sudden death should consider PVC frequency and vulnerability as interrelated variables. Risk assessment must take into consideration both variables. Antiarrhythmic drug efficacy can be assessed in terms of a reduction in trigger mechanisms (PVCs) as well as decreasing myocardial vulnerability (induction of VT at PES). Flecainide acetate, at a reduced dosage of 100 mg twice daily, is effective in both aspects, markedly decreasing PVC frequency and preventing VT induction at PES testing. Holter monitoring and electrophysiologic testing evaluate different aspects of the problem. With the addition of an agent as potent as flecainide, which is devoid of many of the bothersome side effects previously limiting antiarrhythmic therapy, an agent is now available that may be useful to treat both the trigger mechanism and the substrate in sudden death. We must be careful not to worsen the situation through the profound effects of flecainide on depolarization and refractoriness that in some patients cause life-threatening arrhythmias to be more frequent.
室性早搏（触发机制）以及心肌维持危及生命的室性心动过速的易损性（基质）是心源性猝死等式中的两个变量。治疗有猝死风险患者的医生应将室性早搏频率和易损性视为相互关联的变量。风险评估必须考虑这两个变量。抗心律失常药物的疗效可以通过减少触发机制（室性早搏）以及降低心肌易损性（程序电刺激诱发室性心动过速）来评估。醋酸氟卡尼，每日两次，剂量减至100毫克，在这两方面均有效，可显著降低室性早搏频率并在程序电刺激测试时预防室性心动过速的诱发。动态心电图监测和电生理检查评估该问题的不同方面。随着像氟卡尼这样强效药物的加入，它没有许多以前限制抗心律失常治疗的令人烦恼的副作用，现在有一种药物可用于治疗心源性猝死中的触发机制和基质。我们必须小心，以免因氟卡尼对去极化和不应期的深远影响而使情况恶化，这种影响在一些患者中会导致危及生命的心律失常更频繁发生。
