Vascular response to Sirolimus-Eluting Stents delivered with a NonAggressive implantation technique: Comparison of intravascular ultrasound results from the multicenter, Randomized E-SIRIUS, and SIRIUS trials

Background: The effectiveness of SES to reduce the risk of restenosis was initially demonstrated in short lesions using stent implantation with routine pre-dilatation and post-dilatation. This intravascular ultrasound (IVUS) substudy of the E-SIRIUS trial sought to evaluate local arterial responses to sirolimus-eluting stents (SES) delivered with a stent implantation technique allowing direct stenting and only selectively applying high-pressure post-dilatation. Methods and Results: IVUS was performed immediately after intervention and at 8-month follow-up in 51 patients randomised to either bare-metal stents (BMS; Bx-Velocity (TM); N = 20) or SES (Cypher (TM) N = 31). Direct stenting was allowed (24%) and post-dilation was performed only selectively (32%). Lumen dimensions, intimal hyperplasia and vessel remodeling were compared between SES and BMS. Subsequently, results of SES in the E-SIRIUS IVUS substudy (N = 31) were compared to those of SES in the IVUS substudy of the SIRIUS trial (N = 137). SES in SIRIUS IVUS substudy were delivered with 100% pre-dilatation and 77% post-dilatation. Baseline stent and reference segment measurements were similar between BMS and SES in E-SIRIUS IVUS patients. Using SES there was a 96% reduction in intimal hyperplasia volume within the stented segment (1.8 +/- 4.9 vs 50.6 +/- 39.7 mm(3), P < 0.001) and a significantly larger minimal lumen cross sectional area at 8-month follow-up (4.5 +/- 1.1 vs 2.3 +/- 0.9 mm(2), P < 0.001). No vessel remodeling was observed with the use of SES. The applied stent implantation technique resulted in a minimal stent/reference vessel area ratio of 0.75 +/- 0.17 in E-SIRIUS SES as compared to 0.84 +/- 0.23 in SIRIUS SES (P = 0.046). Mean intimal hyperplasia cross-sectional area at follow-up was 0.1 +/- 0.2 mm(2) in the SES group of E-SIRIUS and 0.5 +/- 0.8 mm(2) in the SES group of SIRIUS (P = 0.003). Conclusions: An implantation technique of SES which includes direct stenting and minimizes the use of high-pressure post-dilatation results in less optimal stent expansion. However, follow-up results compare very favourable to those of BMS and are characterised by even less intimal hyperplasia than after a more forceful implantation of SES. (c) 2005 Wiley-Liss, Inc.