Anticoagulation With the Oral Direct Thrombin Inhibitor Dabigatran Does Not Enlarge Hematoma Volume in Experimental Intracerebral Hemorrhage

Background-The direct thrombin inhibitor dabigatran etexilate (DE) may constitute a future replacement of vitamin K antagonists for long-term anticoagulation. Whereas warfarin pretreatment is associated with greater hematoma expansion after intracerebral hemorrhage (ICH), it remains unclear what effect direct thrombin inhibitors would have. Using different experimental models of ICH, this study compared hematoma volume among DE-treated mice, warfarin-treated mice, and controls. Methods and Results-CD-1 mice were fed with DE or warfarin. Sham-treated mice served as controls. At the time point of ICH induction, DE mice revealed an increased activated partial thromboplastin time compared with controls (mean +/- SD 46.1 +/- 5.0 versus 18.0 +/- 1.5 seconds; P=0.022), whereas warfarin pretreatment resulted in a prothrombin time prolongation (51.4 +/- 17.9 versus 10.4 +/- 0.3 seconds; P=0.001). Twenty-four hours after collagenase-induced ICH formation, hematoma volume was 3.8 +/- 2.9 mu L in controls, 4.8 +/- 2.7 mu L in DE mice, and 14.5 +/- 11.8 mu L in warfarin mice (n=16; Welch ANOVA between-group differences P=0.007; posthoc analysis with the Dunnett method: DE versus controls, P=0.899; warfarin versus controls, P<0.001; DE versus warfarin, P=0.001). In addition, a model of laser-induced cerebral microhemorrhage was applied, and the distances that red blood cells and blood plasma were pushed into the brain were quantified. Warfarin mice showed enlarged red blood cell and blood plasma diameters compared to controls, but no difference was found between DE mice and controls. Conclusions-In contrast with warfarin, pretreatment with DE did not increase hematoma volume in 2 different experimental models of ICH. In terms of safety, this observation may represent a potential advantage of anticoagulation with DE over warfarin. (Circulation. 2011;124:1654-1662.)