Abstract 17329: The Impact of Acute and Chronic Stent Expansion on Neointimal Proliferation After Self-Expanding Nitinol Stent Deployment in the Superficial Femoral Artery: A Serial Intravascular Ultrasound Analysis
Purpose: Previous intravascular ultrasound (IVUS) studies have suggested that self-expanding nitinol stents (SENS) produce less vessel wall injury at initial deployment, leading to larger follow-up lumens in coronary arteries. The purpose of this study was to evaluate the mechanical properties of SENS in the superficial femoral artery (SFA) and the subsequent vascular response over the follow-up period by using serial IVUS.
Methods: Twenty-five patients who underwent IVUS examinations before and after SENS deployment in SFA lesions and at 6-month follow-up were enrolled prospectively. Serial quantitative IVUS measurements were performed at 6 different segments: the image slices with minimum lumen area on pre-EVT IVUS, minimum stent area (MSA), distal and proximal edges of SENS, and overlapping segments on post-EVT IVUS. Stent expanding index was calculated as (stent area at follow-up minus post-procedural MSA) divided by post-procedural MSA. Percent neointimal hyperplasia (%NI) was measured as (stent minus lumen area) divided by stent area on follow-up IVUS, and IVUS in-stent restenosis (ISR) was defined as %NI ≥0.6. Stent symmetry index was minimum/maximum stent diameter.
Results: Although stent symmetry index did not change during 6 months, stent area increased 46.3% (ranged 2.71 to 125.56%) in overall analysis. There was a linear relationship between stent expanding index and lumen area at follow-up (p=0.004, r=0.55), and %NI (p=0.01, r=0.26). However, post-EVT stent area was not linearly correlated to %NI at follow-up. IVUS ISRs were identified in 9 patients. No significant differences existed in quantitative IVUS measurements between patients with IVUS ISR and those without IVUS ISR. Stent edge dissections were identified in 10 lesions (18.5%); 6 in proximal stent edge, 3 in distal stent edge, and 1 in both stent edge. Of those, 4 IVUS-detected stent edge dissections (36%) resolved, but remaining 7 (64%) persisted on IVUS at follow-up.
Conclusions: Serial IVUS examinations revealed that the SENS continued to enlarge during the follow-up period. Although neointimal hyperplasia increases with chronic expansile force, larger stent expanding index results in greater net lumen outcome at follow-up after SENSE implantation.
- © 2013 by American Heart Association, Inc.