Impact of lesion morphology on stent elongation during bifurcation PCI: an in vivo OCT study.

Background: Recent observations in silico and in vivo reported that, during proximal optimisation technique, drug-eluting stents (DES) elongate, challenging conventional wisdom. The interaction between plaque morphology and radial expansion is well established, but little is known about the impact of plaque morphology on elongation.
Aims: We aimed to assess the longitudinal mechanical behaviour of contemporary DES in vivo and evaluate the relationship between post-percutaneous coronary intervention (PCI) stent elongation and lesion morphology, as assessed with optical coherence tomography (OCT).
Methods: Patients treated with OCT-guided PCI to left main or left anterior descending artery bifurcations, between July 2017 and March 2022, from the King's Optical coherence Database Analysis Compendium were included. Patients were excluded if there were overlapping stents, if they had undergone prior PCI, or if there was inadequate image quality. Lesions were characterised as fibrocalcific, fibrous or lipid-rich by pre-PCI OCT. Following stent post-dilatation, stent expansion and final stent length were assessed. The primary outcome was the percentage change in stent length from baseline.
Results: Of 501 eligible consecutive patients from this period, 116 were included. The median age was 66 years (interquartile range [IQR] 57-76), 31% were female, and 53.4% were treated for an acute coronary syndrome. A total of 50.0% of lesions were classified as fibrocalcific, 6.9% were fibrous, and 43.1% were lipid-rich. The change in relative stent length was 4.4% (IQR 1.0-8.9), with an increase of 3.1% (IQR 0.5-6.3) in fibrocalcific lesions, 3.3% (IQR 0.5-5.9) in fibrous lesions, and 6.4% (IQR 3.1-11.1) in lipid-rich plaque (p=0.006). In multivariate regression modelling, lipid-rich plaque was an independent predictor of stent elongation (odds ratio 3.689, 95% confidence interval: 1.604-8.484).
Conclusions: Contemporary DES elongate following implantation and post-dilatation, and this is significantly mediated by plaque morphology. This is an important consideration when planning a strategy for DES implantation.