Postoperative stroke in patients on oral anticoagulation undergoing coronary artery bypass surgery

Objective. Patients on long-term warfarin treatment have an inherent high risk of stroke and here we aimed to identify the determinants of postoperative stroke after coronary artery bypass grafting (CABG) in these patients. Methods. A consecutive series of 270 patients on long-term warfarin treatment who underwent isolated CABG in two university hospitals was assessed by logistic regression as well as classification and regression tree (CART) analysis. Results. Postoperative stroke occurred in 10 patients during in-hospital stay (3.7%). Logistic regression showed that CHADS(2) > 2 (p = 0.036), recent thrombolysis (p < 0.0001) and history of deep vein thrombosis (p = 0.025) were independent predictors of postoperative stroke (area under the ROC curve 0.77). CART analysis showed that CHADS(2) > 2, history of stroke/TIA, no preoperative use of aspirin and preoperative use of low molecular weight heparins were associated with an increased risk of stroke (area under the ROC curve of 0.77). Conclusions. Both CART and logistic regression analyses showed that the patient characteristics included in CHADS(2) score are important also in the prediction of postoperative stroke risk. Preoperative antiplatelet treatment may be beneficial in the high risk patients and the preoperative bridging with low molecular weight heparins may even be harmful in this respect.