A MODIFIED THROMBOELASTOGRAPHIC METHOD FOR MONITORING C7E3 FAB IN HEPARINIZED PATIENTS

The monoclonal antibody, c7E3 Fab, binds to the platelet surface fibri nogen receptor (GPIIb/IIIa), inhibiting platelet aggregation and clot retraction. We performed an in vitro study to assess the ability of a modification of the thromboelastograph (MTEG) to detect inhibition of clot strength by c7E3 Fab and its reversal with platelet-rich plasma ( PRP). In the modified assay (MTEG), thrombin was added to whole blood (WE) and platelet-poor plasma (PPP) and the resultant maximum amplitud e (MA) was measured, MA(WB) and MAppp, respec tively. Anticoagulated b lood samples from 17 patients scheduled for cardiac surgery were colle cted for a dose response (Part I; n = 5) and c7E3 Fab reversal (Part I I; n = 12) study. Clot strength was reduced in a dose-dependent manner by c7E3 Fab. Ecteola cellulose effectively reversed the effect of hep arin on the thrombin time and the addition of PRP significantly increa sed the MA(WB) (P < 0.0001) and MA(WB-ppp) (P < 0.0001). Subtracting t he MA(ppp) from MA(WB) significantly magnified the response of MA to t he addition of c7E3 Fab (P = 0.002) and its reversal with PRP (P = 0.0 05). This in vitro study indicates that the MTEG is a responsive assay demonstrating that inhibition by the antiplatelet c7E3 Fab is reversi ble with PRP.