Expansion and malapposition characteristics after bioresorbable vascular scaffold implantation

Objectives: This study sought to investigate the postdeployment expansion and malapposition characteristics of the bioresorbable vascular scaffold (BVS) in real-world practice.

Background: The material construct of the BVS precludes overexpansion, with consequent potential for scaffold underexpansion and malapposition. In metallic stents, these features are associated with an increased risk of adverse events, including stent thrombosis. The postdeployment characteristics of the BVS are yet to be described outside clinical trials, where implantation occurred in straightforward lesion subsets.

Methods: Data from 25 patients undergoing BVS implantation were analyzed. Optical coherence tomography (OCT) was performed both before and after intervention to assess plaque composition, scaffold expansion and strut apposition. Manufacturer's compliance charts were used to predict expected minimal scaffold diameter and area.

Results: OCT pullback (522.2 mm) was analyzed. Overall, BVS achieved 82.5 ± 8.7 and 79.8 ± 12.3% of predicted minimal stent diameter and cross-sectional area (SCA), respectively, with expansion reduced in middle third of the scaffold (central SCA 76.7 ± 10.9% vs. noncentral SCA 81.5 ± 12.7%, P < 0.0001). Improved measures of SCA were observed with 1:1 balloon:vessel predilatation (1:1 PreD 82.8 ± 9.5% vs. No 1:1 PredD 78.6 ± 13.0%, P < 0.0001). Seven thousand six hundred scaffold struts were identified, of which 470 (6.18%) were malapposed. In fibrocalcific (FCa) plaques, malapposition was observed more frequently (FCa 44.4% vs. Other plaques 7.5%, P < 0.001) and at a greater distance from the vessel wall (FCa 0.17 ± 0.10 mm vs. Other plaques 0.14 ± 0.08 mm, P = 0.002).

Conclusions: In this study, BVS expansion was significantly improved by 1:1 PreD, while increased rates of malapposition was associated with FCa plaques.