Optical coherence tomography characteristics of in-stent restenosis are different between first and second generation...

Characterization of neointimal tissue is essential to understand the pathophysiology of in-stent restenosis (ISR) after drug eluting stent (DES) implantation. Using optical coherence tomography (OCT), we compared the morphologic characteristics of ISR between first and second generation DES.

OCT was performed in 66 DES-ISR, defined as > 50% angiographic diameter stenosis within the stented segment. Patients with ISR of first generation sirolimus-eluting stents (SES), paclitaxel eluting stents (PES) and second generation zotarolimus-eluting stents (ZES), everolimus-eluting stents (EES) and biolimus-eluting stents (BES) were enrolled. Quantitative and qualitative ISR tissue analysis was performed at 1-mm intervals along the entire stent, and categorised as homogeneous, heterogeneous and neo-atherosclerosis. The presence of microvessels and peri-strut low intensity area (PSLIA) was determined in all ISR. Neoatherosclerosis was identified by lipid, calcium and thin-cap fibro-atheroma (TCFA) like lesions. We compared the two DES generations at both early (< 1 year) and late (> 1 year) follow-ups.In second generation DES a heterogeneous pattern was prevalent both before and after 1 year (57.1% and 58.6% respectively). Neo-atherosclerosis was more common in the early period in first generation DES (19.4% vs 11.7%, p < 0.01), but after one year was more prevalent in second generation DES (7.0% vs 19.3%, p < 0.01). Similar prevalence of TCFAs was observed in both groups in all comparisons.

When ISR restenosis occurs in second generation DES, the current data suggest a different time course and different morphological characteristics from first generation. Future prospective studies should evaluate the relationship between ISR morphology, time course and clinical events.