• W Dietrich, G Dilthey, M Spannagl, and J A Richter.
• Department of Anesthesia, German Heart Center Munich.
• J. Cardiothorac. Vasc. Anesth. 1995 Jun 1; 9 (3): 250-4.

ObjectiveTo study the influence of preoperative warfarin anticoagulation on postoperative blood loss and allogeneic blood requirement.DesignRetrospective study with a matched control group.SettingUniversity and community hospital, single institutional.Participants240 patients scheduled for cardiac surgery.InterventionsWarfarin sodium was administered to 125 patients preoperatively to prevent thromboembolic complications of their underlying heart disease, 115 served as control. Approximately half of the patients in each group received aprotinin treatment during operation.Measurements And Main ResultsThe international normalized ratio (INR) of the prothrombin time was preoperatively 2.4 (95% confidence interval [CI 0.95]: 2.3 to 2.6) in the warfarin group and 1.1 (CI 0.95: 1.0 to 1.1) in the control group (p < 0.05), and postoperatively 1.9 (CI 0.95: 1.8 to 2.1) (warfarin) and 1.5 (CI 0.95: 1.4 to 1.5) (control) (p < 0.05). The postoperative blood loss after 6 and 12 hours was 381 (CI 0.95: 329 to 434)/505 (CI 0.95: 439 to 571) mL (warfarin) compared with 472 (CI 0.95: 403 to 541)/612 (CI 0.95: 527 to 697) mL (control) (p < 0.05). This difference was blunted when the proteinase inhibitor aprotinin was used. Neither preoperative nor postoperative prothrombin time correlated with blood loss. Despite lower heparin consumption the activated coagulation time (ACT) during CPB was significantly prolonged in the warfarin group.ConclusionsWarfarin pretreatment does not lead to increased bleeding but may even have a beneficial anticoagulant effect that may lead to better preserved postoperative hemostasis and reduced blood loss.

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