Leaflet Immobility and Thrombosis in Transcatheter Aortic Valve Replacement

Arnold C. T. Ng; David R. Holmes; Michael J. Mack; Victoria Delgado; Raj Makkar; Philipp Blanke; Jonathon A. Leipsic; Martin B. Leon; Jeroen J. Bax

Disclosures

Eur Heart J. 2020;41(33):3184-3197. 

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Incidence of Valve Thrombosis

The reported incidence of THV thrombosis is dependent on several factors, including the population being evaluated, diagnostic imaging modality (echocardiography vs. MDCT), and the definition of abnormality. Often, the diagnostic imaging modality utilized depends on the clinical setting (such as haemodynamic instability, or in relation to clinical events such as stroke or systemic embolism), or as part of routine clinical surveillance or randomized controlled clinical trial. Before the advent of TAVR, the reported incidence of bioprosthetic valve thrombosis was <1%.[7] In a meta-analysis that included nine studies totalling 5837 patients with stented porcine bioprosthetic valves, there were only three reported cases of valve thrombosis and a calculated annual incidence of 0.03%. In a large single-centre series from Mayo Clinics that included 397 patients with explanted bioprosthetic valves, 46 (11.6%) patients had pathologically proven leaflet thrombosis.[8] Based on the total 6178 bioprosthetic valve implanted within the reported period, the overall incidence of valve thrombosis requiring repeat surgery was 0.74%. However, these reported surgical incidences were likely an underestimation as the condition is often unrecognized. Even current surgical guidelines recommend including diagnostic imaging tests such as echocardiography to define SVD, non-SVD and valve thrombosis.[9] While it is possible to draw lessons from long-term experiences with SAVR, there are fundamental differences in the valve construct when compared with TAVR. These differences may potentially impact the pathogenesis and natural history of SVD and remain to be fully explored in future studies.

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