Intraoperative coronary thrombosis: Can aprotinin and protamine be incriminated?

Abstract

HE USE OF aprotinin, a proteinase inhibitor. has been advocated recently for coronary artery bypass graft surgery (CABG) to prevent postoperativc blood loss and decrease homologous bloed requirements.1-4 Thc effccts of aprotinin on hemostasis are related to the prcscrvation of platelet receptors GpI,, and Gp II,-JII;,. which assure platelct adhesion to damaged cndothelial cells or thc subendothelial layer. and to an inhibition of the serum proteases kallikrein and plasmin. Aprotinin also inhibits thc coagulation factors XIIa, Xla, IXa, and VIIla, resulting in artifactual prolongation of indices of anticoagulation that measure the intrinsic coagulation cascade. Howcvcr, this agent has no effect on thc cxtrinsic coagulation cascade because it does not influcnce activation of factor Vl1 or subsequent fibrin generation.’ Trcatment with inhibitors of fibrinolysis may theoretically be associated with an incrcascd risk of a thrombotic tendency. In two recent European multicenter studies. no adverse cardiovascular events were reported following aprotinin thcrapy. J.5 Howevcr, Bohrer et al” noticed increascd thrombus formation in aprotinin-treated paticnts. Unexplained thrombosis has also been observed following thc