New insights on acute expansion and longitudinal elongation of bioresorbable vascular scaffolds in vivo and at bench test: a note of caution on reliance to compliance charts and nominal length.

: We performed systematic optical coherence tomography (OCT) analyses after bioresorbable vascular scaffolds (BVS) implantation in a “real world” setting aiming at evaluating scaffold expansion and longitudinal integrity. Background: a comprehensive elucidation of BVS acute performance in the “real-world” setting is lacking. Methods: acute BVS expansion compared with compliance chart information and longitudinal integrity were assessed in 29 patients (32 lesions) by OCT. In addition, bench experiments with four scaffolds were performed with different combinations of deployment pressures and tube stiffness. Results: scaffold underexpansion, using compliance chart information as reference, was observed in 97% of OCT cross-sections in vivo; however, only 8.3% of the cross-section analyzed revealed BVS area <5 mm2 . Calcified plaques were more common in the lowest (9.7%) compared with the mid (8.8%) and highest (6.3%) tertiles of scaffold expansion (P 5 0.003 and P 5 0.001 for lowest vs. mid, and lowest vs. highest, respectively). Seventeen (54.8%) scaffolds were elongated during implantation, but no signs of scaffold fracture were revealed. Elongation and impaired expansion were reproduced in the bench testing when the scaffold was deployed with high pressure in a hard tube. Conclusions: compliance chart information should not be used to predict final BVS dimensions in the clinical setting. While BVS expansion could be potentially impaired by calcified plaques, they may elongate