Transcatheter Aortic Valve Explants: Calcification Patterns and Leaflet Thickening to Inform Repeat Interventions

Degeneration is an inevitable outcome for bioprosthetic heart valves. In the setting of transcatheter aortic valve (TAV) replacement (TAVR), calcifications and leaflet thickening have implications for feasibility and outcomes of repeat interventions, including leaflet modification techniques. In this study, we aimed to investigate the frequency and pattern of leaflet calcification and thickening in explanted TAVs to inform repeat interventions.

TAV explants were obtained from the Explanted THV registry and clinical institutions. Micro-computed tomography imaging and histology were used to evaluated TAV calcium volume, distribution, and leaflet thickening.

Twenty TAV explants were analyzed: 11 self-expanding CoreValve/Evolut (Medtronic, Dublin, Ireland) TAVs, 8 balloon-expandable Sapien 3 (Edwards Lifesciences, Irvine, CA) TAVs, and 1 mechanically-expandable Lotus (Boston Scientific, Marlborough, MA) TAV. Median patient age at explant was 73.0 (interquartile range [IQR], 63.0-81.0) years, with a median time to explant of 3 years and 3 months (IQR, 1 year and 10 months to 4 years and 10 months). Eleven TAVs (55%) had leaflet calcification (median, 77.9; IQR, 24.7-336.1) mm³, and 9 TAVs (45%) had no calcium according to micro-computed tomography. Calcified TAVs had an increased leaflet thickness compared with noncalcific samples (median, 1.02 [IQR, 0.81-1.59] mm vs 0.64 [IQR, 0.47-0.89 mm]; P = 0.006). Leaflet thickness had a positive correlation with implant duration. Calcium distribution was heterogenous within each individual leaflet but also among leaflets of an individual TAV. Calcium pattern appeared to differ between TAV models.

Calcified TAVs tend to have thicker leaflets and calcium distribution appears to vary according to TAV type. These findings might have important clinical implications when considering redo-TAV replacement and leaflet modification techniques.