Changes in platelet function and coagulation after transcatheter aortic valve implantation evaluated with thromboelastography

INTRODUCTION: The possibility of hypercoagulability during the perioperative period of transcatheter aortic valve implantation (TAVI) has been noted; however, there is still a controversy regarding the appropriate perioperative antithrombotic therapy. The study investigated coagulation and platelet functions during the TAVI perioperative period using thromboelastography (TEG) 6s platelet mapping. METHODS: A prospective observational study was conducted on 25 patients undergoing TAVI. TEG platelet mapping was performed at three time points: on admission to the operating room (before heparinisation), on postoperative day (POD) 1 and on POD 3. Perioperative changes observed included: maximum clot strength (MA(HKH)), clot strength without platelet function (MA(ActF)), time to initiation of clots formation by coagulation factors (R(HKH)) and platelet function (G(p)). G(p) is activated by thrombin, and not affected by antiplatelet agents. It is calculated as [(5000×MA(HKH))/(100 – MA(HKH))] − [(5000×MA(ActF))/(100 – MA(ActF))]. Finally, MA(ADP/AA) and G(ADP/AA), which reflect clot strength and platelet aggregation mediated by ADP/thromboxane A(2) receptors, respectively, were also examined using the same method as for G(p). RESULTS: MA(HKH) continued to decrease until POD 3, indicating antithrombotic change after TAVI. G(p) continuously decreased for 3 days after TAVI, while MA(ActF) increased significantly on POD 3. Furthermore, R(HKH) shortened on POD 1 and POD 3, suggesting increased coagulation capacity after TAVI. Finally, G(ADP) in clopidogrel-naive patients was reduced for 3 days after TAVI, while G(AA) in aspirin-naive patients showed no significant change perioperatively. CONCLUSIONS: In this study involving TEG platelet mapping, coagulation capacity increased while platelet function decreased, resulting in antithrombotic change for 3 days after TAVI. The ADP receptor system may be implicated in the decreased platelet function. These results may be useful for considering optimal perioperative antithrombotic therapy in TAVI.