Antiplatelet and Anticoagulant Prophylaxis and Postoperative Blood Loss in Cardiac Surgery: In Response

Abstract

Fries et al. note our apparent paradoxical finding that a combination of platelet inhibition and anticoagulation with heparin preoperatively lead to decreased blood loss postoperatively. As they also noted, our observations may be of importance in view of the increasing use of antiplatelet drugs. They question our grouping together patients who received either clopidogrel or ticlopidine. We did so on the basis that both drugs have similar mechanisms of action, i.e., they are both irreversible inhibitors of platelet ADP receptors. Potency is not an issue; it would be expected that they were used at doses that have equal efficacies. The great majority of the patients received clopidogrel. Typically, a single dose was given in conjunction with cardiac catheterization in both groups. Regarding the frequency of administration of ε-aminocaproic acid and/or aprotinin, there were no statistical differences among the three groups; therefore, an influence from the choice of antifibrinolytic therapy, if any, would be expected to be uniformly distributed among the groups. We differ from Fries et al. in regard to several parameters that we regard as outcome measures rather than baseline differences among the groups. Thus, we consider the higher plasma fibrinogen concentrations at the end of the preoperative treatment period, their apparent contribution to improved hemostasis postoperatively, and decreased surgical and extracorporeal circulation times as favorable outcomes of the combined treatment with ADP-receptor antagonist and heparin. We have not claimed to have established a casual relationship between the combination therapy and certain favorable outcomes; however, our findings suggest possible further areas of study. Suryanarayana Pothula, MD Vajubhai T. Sanchala, MD Basavaraj Nagappala, MD Department of Anesthesiology Mario A. Inchiosa, Jr., PhD Department of Pharmacology, New York Medical College, Valhalla, NY