Thrombosis Risk with Transcatheter Aortic Valve Replacement

Abstract

ABSTRACT The introduction of transcatheter aortic valve replacement (TAVR) has revolutionized the management of aortic stenosis (AS), with procedure numbers rapidly increasing. Although there has been an enthusiastic roll-out of TAVR to increasingly low surgical-risk patients, there are still a number of factors pertaining to this new technology that are incompletely understood. Important unknowns include the real stroke risk associated with TAVR, which extends beyond the periprocedural window; the risk of subclinical valve thrombosis (SCVT); valve degeneration; and the optimal antithrombotic regimen peri- and post-TAVR to minimize these potential complications. Whilst operator experience and improvement in TAVR technology have resulted in a significant reduction in peri-procedural cerebrovascular ischemic events, a greater understanding is required of the pathophysiology of the underlying stroke-risk beyond the perioperative period. Procedure-related, patient-related, and valve-related factors may predispose to stroke post-TAVR. There is an increasing appreciation of the occurrence of SCVT post-TAVR, but the clinical significance of this is unclear. Whilst oral anticoagulation can achieve resolution of SCVT, there are important concerns about bleeding with routine anticoagulation, and treatment with dual-antiplatelet therapy appears to confer no incremental benefit when compared to single-antiplatelet therapy, whilst conferring a higher bleeding risk. In this review, we discuss the incidence, etiology, and clinical significance of TAVR-related thrombosis and how this is affected by antithrombotic therapies. Abbreviations: AF: atrial fibrillation; AS: aortic stenosis; BAV: bicuspid aortic valve; CI: confidence interval; CT: computed tomography; DAPT: dual-antiplatelet therapy; HALT: hypoattenuated leaflet thickening; IQR: interquartile range; NACE: net adverse clinical and cerebral events; NOAC: non-vitamin K antagonist oral anticoagulant; OAC: oral anticoagulation; SAPT: single-antiplatelet therapy; SAVR: surgical aortic valve replacement; SCVT: subclinical valve thrombosis; STS Score: Society of Thoracic Surgery Risk Score; TAVR: transcatheter aortic valve implantation; TIA: transient ischemic attack; VARC: Valve Academic Research Consortium; ViV: valve-in-valve; VKA: vitamin K antagonist.