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), clot strength without platelet function (MA), time to initiation of clots formation by coagulation factors (R) and platelet function (G). G is activated by thrombin, and not affected by antiplatelet agents. It is calculated as [(5000×MA)/(100 - MA)] - [(5000×MA)/(100 - MA)]. Finally, MA and G, which reflect clot strength and platelet aggregation mediated by ADP/thromboxane A receptors, respectively, were also examined using the same method as for G.

Results: MA continued to decrease until POD 3, indicating antithrombotic change after TAVI. G continuously decreased for 3 days after TAVI, while MA increased significantly on POD 3. Furthermore, R shortened on POD 1 and POD 3, suggesting increased coagulation capacity after TAVI. Finally, G in clopidogrel-naive patients was reduced for 3 days after TAVI, while G 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.