Fig. 1. Thrombin–antithrombin complex formation during cardiopulmonary bypass by treatment group, expressed as the increase from a pre–cardiopulmonary bypass baseline to after 60 min of cardiopulmonary bypass. The box plot depicts the median and interquartile range; the whiskers represent the 10th and 90th percentiles. There is a marked intergroup difference in thrombin–antithrombin complex formation during cardiopulmonary bypass by Wilcoxon rank sum test ( P = 0.0003). B = anticoagulation with high-dose bivalirudin; H = anticoagulation with standard-dose heparin; H&B = anticoagulation with standard-dose heparin plus low-dose bivalirudin.