Bridging Anticoagulation After Mechanical Aortic Heart Valve Replacement: A Questionable Routine

Abstract

This retrospective single-center study evaluates differences in bleeding and thrombotic events between a homogenous group of patients undergoing mechanical aortic valve replacement who either received or did not receive intravenous unfractionated heparin or subcutaneous low-molecular weight heparin as bridging strategy to warfarin therapy. Clinical data on a total of 158 patients undergoing mechanical aortic valve replacement at our center between 2001 and 2014 were collected. Patients were grouped according to postoperative anticoagulation strategy: warfarin only (n= 53) and warfarin plus heparin bridge (n= 105). The outcomes of interest were bleeding event and thromboembolic event recorded during hospital stay. Patients' baseline characteristics were comparable between the two groups except for preoperative atrial fibrillation, which was more common in the warfarin plus heparin group than the warfarin group (p= 0.04). There were significantly more bleeding complications in the warfarin plus heparin group versus warfarin group as evidenced by higher rates of pericardial effusions (24% versus 8%, p= 0.02) and reoperation for bleeding (8% versus 0%, p= 0.05). All observed thromboembolic events (n= 4) occurred in the warfarin plus heparin group (p= 0.55). Logistic regression analysis identified group assignment (warfarin plus heparin versus warfarin only) to be significantly associated with the odds of bleeding (odds ratio 4.46, 95% confidence interval:1.42 to 14.02, p= 0.01). Bridging anticoagulation therapy increases the chances of bleeding in the postoperative phase for mechanical aortic valve replacement patients. Owing to low incidence, no statistically significant difference was detected for thromboembolic event rates.