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The aim was to evaluate the 3-year biodegradation of the struts of the bioresorbable vascular scaffold (BVS).
We have analyzed some serial pull-backs of patient ABCB-097969-005 (cohort B2 of the ABSORB trial) at baseline, 12- and 36-month follow-ups within the protocols and definitions of the Imaging Corelab of Cardialysis BV (Rotterdam, NL). 268 and 46 frames were examined by the frame-by-frame and 1-mm optical coherence tomography (OCT) C7XR analyses with the QCU-CMS software (v 4.68).
Both frame-by-frame and 1-mm analyses with the same accuracy demonstrate enhancement in the number of elongated struts (mean from 80/867, 10.95% to 124/717, 17.55% of struts) and internal scaffold area (a sum of areas 3.48 mm2 to 4.08 mm2) from baseline to 3-year follow-up amid some lumen loss (mean 165.59 mm3 to 143.43 mm3), and increase of stent volume (mean 153.84 mm3 to 184.17 mm3) (p<0.05). This is an evidence of the BVS biodegradation with simultaneous artery remodeling leading to the swelling and dynamic dislocation of struts with accumulation of unidentified tissue, which imitates the bioresorbing BVS imparing interpretation of the scaffold area.
This study could not confirm the existence of the elongated struts as a real phenomenon. An increase in the scaffold area corresponds to the biomechanical remodeling of the tissue as a biological response to the transient scaffolding. Scaffold area assessed by OCT is not properly accurate to judge the biodegradation of BVS.