Ann Thorac Surg 2007;84:840
© 2007 The Society of Thoracic Surgeons
Original Articles: Cardiovascular
Invited commentary
Alan F. Merry, MB ChB, FANZCA
Department of Anesthesiology, University of Auckland, Private Bag 92019, Auckland, New Zealand 1003
(Email: a.merry{at}auckland.ac.nz).
This study [1] adds to the confidence clinicians can have in the direct thrombin inhibitor bivalirudin as an anticoagulant for off-pump coronary artery bypass (OPCAB) surgery when heparin is contraindicated. Anticoagulation for cardiac surgery in patients with heparin-induced thrombocytopenia (HIT) or thrombotic syndrome (TS) is particularly difficult. It is becoming increasingly apparent that the direct thrombin inhibitor bivalirudin has considerable merit as an alternative to heparin in this situation. However there is no reversal agent for bivalirudin, and with a half-life of 25 minutes, its duration of action is short rather than ephemeral, so concern as to the possibility of major hemorrhage after cardiopulmonary bypass (CPB) surgery is understandable, although bivalirudin may still be the best available choice when heparin is not an option. When feasible, OPCAB is less difficult than CPB surgery in respect to managing anticoagulation. An activated clotting time (ACT) of slightly more than 300 seconds provides satisfactory results; this is lower than the minimum ACT believed necessary to manage CPB, so that the time required for the effect of bivalirudin to wear off is shorter, and off-pump surgery is associated with less of a tendency to bleed anyway. Indeed, some practitioners have chosen not to reverse heparin (or only partially to reverse it) after OPCAB, in the hope that this may improve graft patency, and this approach does not seem to be unduly prone to hemorrhage. Therefore these patients lend themselves very nicely to the use of bivalirudin.
Although HIT and TS are greatly feared, they are not particularly common, and the prospective identification of patients for inclusion in a study such as this is difficult. Therefore the authors are to be congratulated on this important report. Even in patients without HIT or TS, heparin and protamine are far from perfect anticoagulants. Other clinical challenges or concerns, such as the postoperative presence of antibodies to heparin, resistance to heparin, or allergies to protamine are quite frequently encountered in the management of patients undergoing cardiac surgery. We still have much to learn about direct thrombin inhibitors in this context, but it will be interesting to see how the use of these drugs progresses during the next decade.
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References
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- Dyke CM, Aldea G, Koster A, et al. Off-pump coronary artery bypass with bivalirudin for patients with heparin-induced thrombocytopenia or antiplatelet factor four/heparin antibodies Ann Thorac Surg 2007;84:836-840.[Abstract/Free Full Text]
Related Article
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Off-Pump Coronary Artery Bypass With Bivalirudin for Patients With Heparin-Induced Thrombocytopenia or Antiplatelet Factor Four/Heparin Antibodies
- Cornelius M. Dyke, Gabriel Aldea, Andreas Koster, Nicholas Smedira, Edwin Avery, Solomon Aronson, Bruce D. Spiess, and A. Michael Lincoff
Ann. Thorac. Surg. 2007 84: 836-839.
[Abstract]
[Full Text]
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