Pathology of self-expanding transcatheter aortic valves: Findings from the CoreValve US pivotal trials.

ABSTRACT

BACKGROUND: Transcatheter aortic valve replacement (TAVR) has recently become an alternative to surgical aortic valve replacement for patients with severe aortic stenosis. However, paravalvular leaks, possible leaflet thrombosis, and device durability following TAVR remain unresolved issues. METHODS AND RESULTS: We conducted the first systematic microscopic and macroscopic pathologic analysis of self-expanding CoreValve transcatheter aortic valves removed at autopsy or surgically from the U.S. pivotal trial of extreme- and high-risk patients. Implants were evaluated for histopathologic changes in the valve frame and leaflets. Thrombus/neointima on the leaflets was graded depending on the leaflet thickness and the extent of leaflet involvement. Inflammation, calcification, and structural integrity were also assessed. A total of 21 cases (median age 86.0 years [IQR, 79.0-91.0]), with median duration of implant duration of 17.0 days ranged from 0 to 503 days were evaluated. No valve frame fracture was observed and severe paravalvular gaps were uncommon. Inflammation and thrombus in the valve frame was minimal, but neointimal growth increased overtime. Symptomatic valve thrombosis was observed in one case (5%) and subclinical moderate leaflet thrombus was observed in four additional cases (19%). Inflammation of the leaflets was mild, while structural changes were minimal, and one case had infective endocarditis. Pannus or leaflet calcification were not observed. CONCLUSIONS: This first systematic macroscopic and microscopic pathologic analysis of self-expanding transcatheter aortic valves demonstrates favorable short-term pathologic findings. However, our finding of subclinical leaflet thrombus formation confirms prior observations and warrants further investigation.