Comparison of serial optical coherence tomography imaging following aggressive stent expansion technique: insight from the MECHANISM study.

To compare early vascular healing following cobalt-chromium everolimus-eluting stent (CoCr-EES) implantation between groups with or without aggressive stent expansion in patients treated by CoCr-EES for stable coronary artery disease (CAD). Seventy-one stable CAD lesions underwent CoCr-EES implantation and analysis of serial optical coherence tomography (OCT) images obtained post-procedure and at early-term (1- or 3-month) follow-up. The endpoints of this study were neointimal thickness at the time of 1- or 3-month OCT and presence and healing of stent edge dissection. Aggressive stent expansion was defined as a lesion complying with ILUMIEN III sizing protocol; that is, external elastic lamina (EEL) diameter minus maximum balloon diameter ≤ 0.25 mm.  Comparing groups with and without aggressive stent expansion, median neointimal thickness at 1 and 3 months after CoCr-EES implantation was similar (1 month: 0.031 mm vs. 0.041 mm, respectively, p = 0.27; 3 months: 0.036 mm vs. 0.040 mm, respectively, p = 0.84). Regarding stent edge findings, the presence of any stent edge dissection immediately after percutaneous coronary intervention was also similar between the groups (25% vs. 15%, respectively; p = 0.30) and most stent edge dissections resolved completely within 3 months, regardless of location or dissection severity. After 1 year, no clinically driven target lesion revascularization or stent thrombosis was observed in either cohort. Even after aggressive stent expansion, early neointimal proliferation appeared modest with CoCr-EES implantation, and most stent edge dissections had resolved by 3 months. These findings may support the feasibility of EEL-based sizing by pre-stenting OCT.