Comparison of acute vessel wall injury after self-expanding stent and conventional balloon-expandable stent implantation: A study with optical coherence tomography

Background: The acute impact in vivo from a selfexpanding stent on the vessel wall has not been sufficiently evaluated. Objectives: We sought to compare acute in vivo injury on the vessel wall and the clinical impact between a self-expanding coronary stent and conventional balloon-expandable stents immediately after stent implantation. Methods: We included 40 patients (45 vessels) with stable or unstable angina who were assigned to either the self-expanding stent (vProtect® Luminal Shield) group (n ≤ 9; Group 1) or the conventional balloon-expandable stent group (n ≤ 36; Group 2). Optical coherence tomography (OCT) was performed after stent deployment, as were qualitative and quantitative assessments of tissue prolapse, intrastent dissection, edge dissection and incomplete stent apposition. Results: Tissue prolapse was visible in all vessels in both groups. The corrected tissue prolapse area by stent length was larger in Group 2 than in Group 1 (0.06 ± 0.06 vs. 0.02 ± 0.01 mm2; p < 0.001). Intrastent dissection was more frequently seen in Group 2 (33/36 vs. 4/9 vessels; p ≤ 0.004) and the mean length of the dissection flap was greater in Group 2 than in Group 1 (277.6 ± 110.0 vs. 76.9 ± 103.7 μm; p < 0.001). Although edge dissection was not detected in Group 1, it was visible in 19/36 vessels (52.8) in Group 2. The frequency of incomplete stent apposition was not significantly different between Group 2 and Group 1 (23/36 vs. 7/9 vessels, p ≤ 0.7), but the mean depth of incomplete stent apposition was greater in Group 2 than in Group 1 (268.2 ± 72.1 vs. 178.2 ± 156.7 μm, p ≤ 0.03). ConclusionS: A selfexpanding stent was associated with less intrastent dissection and edge dissection than conventional balloon-expandable stents with OCT.