Circulation. 1991 Aug;84(2):527-39. doi: 10.1161/01.cir.84.2.527.
Atrial fibrillation in the absence of rheumatic valvular disease is associated with a fivefold to sevenfold increased risk of ischemic stroke.
The Stroke Prevention in Atrial Fibrillation Study, a multicenter, randomized trial, compared 325 mg/day aspirin (double-blind) or warfarin with placebo for prevention of ischemic stroke and systemic embolism (primary events), and included 1,330 inpatients and outpatients with constant or intermittent atrial fibrillation. During a mean follow-up of 1.3 years, the rate of primary events in patients assigned to placebo was 6.3% per year and was reduced by 42% in those assigned to aspirin (3.6% per year; p = 0.02; 95% confidence interval, 9-63%). In the subgroup of warfarin-eligible patients (most less than 76 years old), warfarin dose-adjusted to prolong prothrombin time to 1.3-fold to 1.8-fold that of control reduced the risk of primary events by 67% (warfarin versus placebo, 2.3% versus 7.4% per year; p = 0.01; 95% confidence interval, 27-85%). Primary events or death were reduced 58% (p = 0.01) by warfarin and 32% (p = 0.02) by aspirin. The risk of significant bleeding was 1.5%, 1.4%, and 1.6% per year in patients assigned to warfarin, aspirin, and placebo, respectively.
Aspirin and warfarin are both effective in reducing ischemic stroke and systemic embolism in patients with atrial fibrillation. Because warfarin-eligible patients composed a subset of all aspirin-eligible patients, the magnitude of reduction in events by warfarin versus aspirin cannot be compared. Too few events occurred in warfarin-eligible patients to directly assess the relative benefit of aspirin compared with warfarin, and the trial is continuing to address this issue. Patients with nonrheumatic atrial fibrillation who can safely take either aspirin or warfarin should receive prophylactic antithrombotic therapy to reduce the risk of stroke.
非风湿性瓣膜病性心房颤动与缺血性卒中风险增加五至七倍相关。
心房颤动卒中预防研究是一项多中心随机试验，比较了每日325毫克阿司匹林（双盲）或华法林与安慰剂预防缺血性卒中和全身性栓塞（主要事件）的效果，纳入了1330例持续性或间歇性心房颤动的住院和门诊患者。在平均1.3年的随访期间，分配至安慰剂组的患者主要事件发生率为每年6.3%，而分配至阿司匹林组的患者该发生率降低了42%（每年3.6%；p = 0.02；95%置信区间，9 - 63%）。在符合使用华法林条件的患者亚组（大多数年龄小于76岁）中，将华法林剂量调整至使凝血酶原时间延长至对照值的1.3至1.8倍，可使主要事件风险降低67%（华法林组与安慰剂组相比，每年分别为2.3%和7.4%；p = 0.01；95%置信区间，27 - 85%）。华法林使主要事件或死亡风险降低58%（p = 0.01），阿司匹林使其降低32%（p = 0.02）。分配至华法林、阿司匹林和安慰剂组的患者每年严重出血风险分别为1.5%、1.4%和1.6%。
阿司匹林和华法林在降低心房颤动患者缺血性卒中和全身性栓塞方面均有效。由于符合使用华法林条件的患者是所有符合使用阿司匹林条件患者的一个子集，因此无法比较华法林与阿司匹林在降低事件发生率方面的幅度。符合使用华法林条件的患者发生的事件过少，无法直接评估阿司匹林与华法林相比的相对益处，该试验仍在继续解决这一问题。能够安全服用阿司匹林或华法林的非风湿性心房颤动患者应接受预防性抗血栓治疗以降低卒中风险。
