BACKGROUND:

Fragmin (Dalteparin, Pharmacia Ltd, Milton Keynes, UK), a low molecular weight heparin, is now recommended in the treatment of unstable angina. Due to the greater bioavailability and longer half-life of Fragmin compared with conventional heparin we postulated that this may influence postoperative bleeding after cardiac surgery for unstable angina.

METHODS:

We investigated the influence of the agent on postoperative bleeding after cardiac surgery. Patients undergoing first-time coronary artery bypass grafting were prospectively studied in four groups: group A (n = 100) were elective patients; group B (n = 60) had unstable angina and received conventional heparin intravenously until operation; group C (n = 115) received 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 < 0.001) and increased blood transfusion than groups A, B, and C (p = 0.047). Patients receiving Fragmin more than 12 hours before surgery (group C) had similar 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.