Effect ol low molecular weight heparin (Fragmin) on bleeding after cardiacsurgery

Background. Fragmin (Dalteparin, Pharmacia Ltd, Milton Keynes, UK) a low mo lecular weight heparin, is now recommended in the treatment of unstable ang ina. Due to the greater bioavailability and longer half-life of Fragmin com pared with conventional heparin we postulated that this may influence posto perative bleeding after cardiac surgery for unstable angina. Methods. We investigated the influence of the agent on postoperative bleedi ng after cardiac surgery. Patients undergoing first-time coronary artery by pass grafting were prospectively studied in four groups: group A (n = 100) were elective patients; group B (n = 60) had unstable angina and received c onventional heparin intravenously until operation group C (n = 115) receive d Fragmin with the last dose administered more than 12 hours before surgery ; and group D (n = 115) received Fragmin within 12 hours of operation. Results. Patients in group D had significantly greater blood loss (p < 0.00 1) and increased blood transfusion than groups A, B, and C (p = 0.047), Pat ients receiving Fragmin more than 12 hours before surgery (group C) had sim ilar rates of blood loss and transfusion to group B (p > 0.05) but greater than in group A (p = 0.021). There were no differences in reopening rate. Conclusions, The risks of bleeding and transfusion must be weighed against the risks of acute ischemic events if Fragmin is stopped more than 12 hours before operation. (C) 2000 by The Society of Thoracic Surgeons.