Aims: We investigated in a prospective, longitudinal, non-randomised study the role of stent recoil (SR) in 4 different DES made of stainless steel (A and B), cobalt chromium (C), and platinum chromium (D) alloys in patients with stable angina. Eluted drugs were paclitaxel (A and B) and everolimus (C and D).
Methods and results: A novel methodology for SR assessment using digitally enhanced angiographic stent imaging (DEASI) was applied. DEASI was performed during DES deployment at 16 Atm and after balloon deflation. Radio-transparent saline-filled balloons were used in all cases for optimal DEASI visualisation and quantification of stent dimensions during deployment. Absolute SR (mm) was calculated as mean stent diameter shift after balloon deflation, and relative SR (%) as: (absolute SR/stent diameter@16Atm)x100. Nine-month follow-up angiography was scheduled at discharge and completed in 57 (59%) implanted stents. QCA was performed to calculate relevant parameters of DES performance, including late luminal loss (LLL). A per stenosis analysis of data was followed. A total of 97 DES (22 A, 25 B, 26 C and 24 D) were implanted. No significant baseline differences were noted, other than larger nominal stent size in A and less stenosis calcification in C groups. Overall absolute SR was 0.27±0.14 mm, with significant differences between B (0.31±0.18 mm) and D (0.23±0.15 mm, p=0.04) groups. Overall relative SR was 8.66±4.10%. Average LLL was 0.47±0.48 mm. There were significant differences in LLL between DES, ranging from 0.31±0.18 (D) to 0.95±0.79 (B) mm. Angiographic restenosis (>50% diameter stenosis) rates were 0% A (0/17), 23% B (3/13), 0% C (0/16) and 0% D (0/11). Univariate regression analysis revealed a significant relationship between SR and LLL (r=0.27, p=0.04). Multivariate regression analysis showed a significant relationship between both absolute and relative SR and LLL (controlling for calcification, nominal stent size and DES type). Average expected increase in LLL per unit of relative SR was 0.04 mm and, taking D as a reference (DES group with less SR and LLL), the expected increase in LLL was 0.03 mm for A, 0.63 mm for B, and -0.36E-6 mm for C type DES.
Conclusions: 1) Marked variations in SR between different DES were documented in vivo using a novel measurement technique based on DEASI. 2) SR (controlled for calcification, nominal stent size and DES type) was identified as a significant predictor of LLL. 3) These observations suggest that both structural and antiproliferative characteristics of DES influence long-term outcome. SR should be taken into account in the design of future longitudinal studies assessing DES performance.