Serial analysis of the malapposed and uncovered struts of the new generation of everolimus-eluting bioresorbable scaffold with optical coherence tomography

Objectives: The aim of this study is to assess the serial changes in strut apposition and coverage of the bioresorbable vascular scaffolds (BVS) and to relate this with the presence of intraluminal masses at 6 months with optical coherence tomography (OCT). Background: Incomplete strut/scaffold apposition (ISA) and uncovered struts are related to a higher risk of scaffold thrombosis. Bioresorbable vascular scaffolds can potentially avoid the risk of scaffold thrombosis because of its complete resorption. However, during the resorption period, the risk of scaffold thrombosis is unknown. Methods: OCT was performed in 25 patients at baseline and 6 months. Struts were classified according to apposition, coverage, and presence of intraluminal masses. Persistent ISA was defined as malapposed struts present at baseline and follow-up, and late acquired ISA as ISA developing at follow-up, and scaffold pattern irregularities when the strut distribution suggested scaffold fracture. Results: At baseline, 3,686 struts were analyzed: 128 (4%) were ISA, and 53 (1%) were located over side-branches (SB). At 6 months, 3,905 struts were analyzed: 32 (1%) ISA, and 35 (1%) at the SB. Persistent ISA was observed more frequently than late acquired-ISA (81% vs. 16%, respectively; 3% were unmatchable). Late acquired ISA was associated with scaffold pattern irregularities, which were related to overstretching of the scaffold. Uncovered struts (63 struts, 2%) were more frequently observed in ISA and SB struts, compared with apposed struts (29% vs. 1%; p < 0.01). Intraluminal masses (14 cross-sections, 3%; in 6 patients, 24%) were more frequently located at the site of ISA and/or uncovered struts (39% vs. 2% and 13% vs. 2%, respectively; p < 0.01). Conclusions: The lack of strut apposition at baseline is related to the presence of uncovered struts and intraluminal masses at 6 month. An appropriate balloon/artery ratio respecting the actual vessel size and avoiding the overstretching of the scaffold can potentially decrease the risk of scaffold thrombosis. (ABSORB Clinical Investigation, Cohort B [ABSORB B]; NCT00856856)