Circumferential evaluation of the neointima by optical coherence tomography after ABSORB bioresorbable vascular scaffold implantation: Can the scaffold cap the plaque?

Objective To quantify the circumferential healing process at 6 and 12 months following scaffold implantation. Background The healing process following stent implantation consists of tissue growing on the top of and in the space between each strut. With the ABSORB bioresorbable vascular scaffold (BVS), the outer circumference of the scaffold is detectable by optical coherence tomography (OCT), allowing a more accurate and complete evaluation of the intra-scaffold neointima. Methods A total of 58 patients (59 lesions), who received an ABSORB BVS 1.1 implantation and a subsequent OCT investigation at 6 (n =28 patients/lesions) or 12 (n =30 patients with 31 lesions) months follow-up were included in the analysis. The thickness of the neointima was calculated circumferentially in the area between the abluminal side of the scaffold and the lumen by means of an automated detection algorithm. The symmetry of the neointima thickness in each cross section was evaluated as the ratio between minimum and maximum thickness. Results The neointima area was not different between 6 and 12 months follow-up (1.57±0.42mm2 vs. 1.64±0.77mm2; p =0.691). No difference was also found in the mean thickness of the neointima (median [IQR]) between the two follow-up time points (210μm [180–260]) vs. 220μm [150–260]; p =0.904). However, the symmetry of the neointima thickness was higher at 12 than at 6 months follow-up (0.23 [0.13–0.28] vs. 0.16 [0.08–0.21], p =0.019). Conclusions A circumferential evaluation of the healing process following ABSORB implantation is feasible, showing the formation of a neointima layer, that resembles a thick fibrous cap, known for its contribution to plaque stability.