Antithrombotic treatment in patients undergoing transcatheter aortic valve implantation (TAVI)

Carefully balancing risks of antithrombotic therapy after transcatheter aortic valve implantation (TAVI)

Do bleeding events outweigh thrombotic complications when patients are given antithrombotic agents after transcatheter aortic valve implantation, an established treatment for symptomatic patients with severe aortic valvular disease not suited for conventional surgical aortic valve replacement?

"Since the introduction of transcatheter aortic valve implantation (TAVI), we empirically treat patients with additional clopidogrel for at least a month after the procedure," Vincent J Nijenhuis, MD, Dept. of Cardiology, St. Antonius Hospital, Nieuwegein, the Netherlands, said. Nonetheless, he stressed that the rate of bleeding seems to outweigh the thrombotic complications. With his upcoming review, Nijenhuis hopes "to make the public aware of the consequences of bleeding and thrombotic complications, and the need of evidence for antithrombotic treatment after TAVI."

In recent years development of TAVI devices rapidly progressed, for example, with regard to paravalvular aortic regurgitation. Slimmer delivery systems to reduce the risk of vascular complications and bleeding have become available as well as embolic protection devices to catch or deflect embolic material to prevent neurological events. However, this is just the beginning of the development, and upcoming studies should definitely focus on tailored periprocedural antithrombotic treatment. Despite improving experience and techniques, ischemic and bleeding complications after TAVI remain prevalent and impair survival. Patients undergoing TAVI are prone to complications, their risk depending on many intrinsic and extrinsic factors. Unfortunately, the data regarding the etiology of thromboembolic events are scarce.

Properly conducted randomized research is urgently awaited

Nijenhuis and his team searched the literature on antithrombotic therapy following TAVI for epidemiology, etiology and clinical consequences of ischemic and bleeding complications associated with TAVI. They soon realized that in a large number of studies the antithrombotic regimen was not mentioned and that in addition baseline characteristics between studies varied widely. They also observed that trials on the optimal antithrombotic therapy after TAVI are of limited study quality in terms of Cochrane criteria. Because of the lack of evidence and specifically designed studies, the authors were unable to draw any hard conclusions with regard to safety and efficacy of the antithrombotic regimen after TAVI. Small exploratory studies, however, suggest that additional clopidogrel after TAVI only affects bleeding and not ischemic complications. “Properly conducted randomized research is urgently awaited”, Nijenhuis concluded.

Nijenhuis speculated that "we hypothesize that the omission of clopidogrel the first three months after TAVI is safer and not less beneficial than the addition of clopidogrel to aspirin or oral anticoagulation," he has recently designed a randomized, multicenter, open-label trial (POPular-TAVI) testing safety, net-clinical benefit and efficacy of omission of clopidogrel in two cohorts. Finally, the authors of this review also want to appeal to authors of future TAVI-related studies to include what kind of antithrombotic regimen was prescribed.
Text: Werner Zwick, M.A., Munich, Germany

Vincent J. Nijenhuis, Naoual Bennaghmouch, Jan-Peter van Kuijk, Davide Capodanno and Jurriën M. ten Berg: Opens external link in new windowAntithrombotic treatment in patients undergoing transcatheter aortic valve implantation (TAVI). Thromb Haemost 2015: 113/4 (Apr) pp. 671–909

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