THE WARFARIN-ASPIRIN SYMPTOMATIC INTRACRANIAL DISEASE STUDY

We conducted a retrospective, multicenter study to compare the efficac y of warfarin with aspirin for the prevention of major vascular events (ischemic stroke, myocardial infarction, or sudden death) in patients with symptomatic stenosis of a major intracranial artery. Patients wi th 50 to 99% stenosis of an intracranial artery (carotid; anterior, mi ddle, or posterior cerebral; vertebral; or basilar) were identified by reviewing the results of consecutive angiograms performed at particip ating centers between 1985 and 1991. Only patients with TIA or stroke in the territory of the stenotic artery qualified for inclusion in the study. Patients were prescribed warfarin or aspirin according to loca l physician preference and were followed by chart review and personal or telephone interview. Seven centers enrolled 151 patients; 88 were t reated with warfarin and 63 were treated with aspirin. Median follow-u p was 14.7 months (warfarin group) and 19.3 months (aspirin group). Va scular risk factors and mean percent stenosis of the symptomatic arter y were similar in the two groups, yet the rates of major vascular even ts were 18.1 per 100 patient-years of follow-up in the aspirin group ( stroke rate, 10.4/100 patient-years; myocardial infarction or sudden d eath rate, 7.7/100 patient-years) compared with 8.4 per 100 patient-ye ars of follow-up in the warfarin group (stroke rate, 3.6/100 patient-y ears; myocardial infarction or sudden death rate, 4.8/100 patient-year s). Kaplan-Meier analysis showed a significantly higher percentage of patients free of major vascular events among patients treated with war farin (p = 0.01). The relative risk of a major vascular event in those treated with warfarin was 0.46 (95% CI, 0.23 to 0.86) compared with p atients treated with aspirin. Major hemorrhagic complications occurred in three patients on warfarin (including two deaths) during 166 patie nt-years of follow-up and in none of the patients on aspirin during 14 3 patient-years of follow-up. This study suggests a favorable risk/ben efit ratio for warfarin compared with aspirin for the prevention of ma jor vascular events in patients with symptomatic intracranial large-ar tery stenosis. A prospective, randomized study is needed to confirm th ese findings.