Impaired cerebrovascular autoregulation distal to carotid stenosis predicts stroke at cardiac surgery with extracorporeal circulation

Background and Purpose: Carotid stenosis is associated with an increased risk of stroke at cardiac surgery with extracorporeal circulation. Relevance of stenosis-induced impairment of cerebrovascular autoregulation is unknown.

Methods: We assessed stroke risk in relation to carotid stenosis and corresponding cerebrovascular autoregulation. 2797 of 7120 consecutively operated patients underwent preoperative carotid Doppler/duplex sonography including transcranial Doppler carbon dioxide testing for cerebrovascular reserve capacity. Patients were followed-up for 30 days postoperatively.

Results: Ischemic strokes occurred in 59 of 5594 carotid artery distribution territories. Greater risk was observed in patients with an exhausted cerebrovascular reserve capacity distal to high-grade stenosis or occlusion (relative risk [RR], 22.8; 95% confidence interval [CI], 8.0 to 64.6). An ischemic stroke compatible to be related to carotid disease occurred in 42 of 2269 patients (1.9%) without relevant stenosis, 7 of 482 patients (1.5%) with stenosis/occlusion and intact autoregulation (RR, 0.8; 95% CI, 0.4 to 1.7), and 3 of 11 patients (27.3%) with impaired autoregulation (RR, 14.7; 95% CI, 5.4 to 40.5). An impaired autoregulation remained predictive also after adjustment for potential confounders (odds ratio, 25.2; 95% CI, 5.0 to 127.9).

Conclusions: An impaired cerebrovascular autoregulation distal to carotid artery stenosis/occlusion is a risk factor for an ischemic carotid territory stroke during surgery with cardiopulmonary bypass.