Risk factors associated with early seizure after cardiopulmonary bypass (CPB) were examined. The role of tranexamic acid in seizure development was evaluated.

Early seizure was defined as a seizure occurring within 24 hours of CPB, without neurologic deficit or new lesion on brain imaging. Independent determinants of early seizure were examined by multivariate logistic regression modelling.

Between 2004 and 2009, early seizure occurred in 119 of 8,929 patients (1.3%). A significant increase in the yearly rate of early seizure was observed in 2004 (0.73%) vs 2009 (1.97%; p < 0.0001). Multivariate analysis showed the following variables were independent predictors of early seizure: age older than 75 years (adjusted odds ratio [OR], 2.1; p = 0.0001), open heart procedure (OR, 12.0; p < 0.0001), preoperative renal failure (OR, 3.2; p < 0.0001), peripheral vascular disease (OR, 1.8; p = 0.02), and total tranexamic acid dose of 100 mg/kg or more (OR, 2.6; p < 0.0001). Risk of seizure was related to tranexamic acid in a dose-dependent fashion, with higher doses associated with increased risk of seizure. The use of CO₂ in a subset of patients undergoing open heart procedures did not decrease the incidence of early seizure (4.8% vs 2.5% for no CO₂; p = 0.27). Postoperative chest tube drainage and blood product use were similar between patients receiving low-dose and high-dose tranexamic acid.

High-dose tranexamic acid (≥ 100 mg/kg) is independently associated with an increased risk of early seizure. Future tranexamic acid trials should assess the blood-conserving effect of tranexamic acid at a lower dosage and specifically monitor for seizure occurrence.