ASYMPTOMATIC CAROTID-ARTERY STENOSIS AND STROKE IN PATIENTS UNDERGOING CARDIOPULMONARY BYPASS

Purpose: This study was undertaken to assess the natural history of ca rotid artery stenosis in patients undergoing cardiopulmonary bypass (C PB) at a Veterans Administration Medical Center. Methods: Between Janu ary 1989 and August 1993, all patients undergoing CPB were offered pre operative carotid artery ultrasound screening as part of an investigat ive protocol. Patients were monitored in-hospital for the occurrence o f perioperative neurologic deficit. Results: A total of 582 patients u nderwent carotid artery ultrasound screening. Greater than 50% stenosi s or occlusion of one or both internal carotid arteries was present in 130 patients (22%), with 80% or greater stenosis or occlusion of one or both arteries present in 70 patients (12%). In-hospital stroke or d eath occurred in 12 (2.1%) and 36 (6.2%) patients, respectively. Of th e 12 strokes, five were global and seven were hemispheric in distribut ion. Of the five patients who had global events, none had evidence of carotid artery stenosis. However, of the seven patients who had hemisp heric events, five had significant 50% or greater stenosis or occlusio n of the internal carotid artery ipsilateral to the hemispheric stroke . Therefore the presence of carotid artery stenosis or occlusion was s ignificantly associated with hemispheric stroke (no stenosis 0.34% vs stenosis 3.8%; p = 0.0072). Furthermore, the risk of hemispheric strok e in patients with unilateral 80% to 99% stenosis, bilateral 50% to 99 % stenosis, or unilateral occlusion with contralateral 50% or greater stenosis was 5.3% (4 of 75). No strokes occurred in patients with unil ateral 50% to 79% stenosis (n = 52). Conclusions: It is concluded that carotid atherosclerosis is a risk factor for hemispheric stroke in pa tients undergoing CPB.