Abstract 4923: Long Term Follow-Up of Neointimal Coverage after Silorimus-Eluting Stent Implantation -Optical Coherence Tomography Study
OBJECTIVES: Late thrombosis after sirolimus-eluting stents (SES) implantation is a major clinical problem probably due to the failure of re-endothelialization over the implanted stent struts. Recent studies have shown that intravascular ultrasound (IVUS) can not detect neointimal hyperplasia (NIH) on most SES even at chronic phase. Optical coherence tomography (OCT) is a new intravascular imaging modality with a resolution of 10μm. In this study, we evaluate the serial changes of neointimal growth over the SES struts at long term follow-up by using intravascular OCT.
METHODS: Thirty-six patients after SES-implantation (66.5 y/o, 9 patients with ACS and 27 with stable angina) were underwent intravascular OCT study at follow-up angiography. Patients were classified into 3 groups according to follow-up period;<8 months (G1), 8 to 24 months (G2), and 24 to 38 months (G3). Mean NIH thickness inside SES struts was measured in proximal, mid, and distal segments of each stent. Uncovered strut by neointima was counted at 1-mm intervals.
RESULTS: A total of 43 coronary segments with SES in 36 patients were studied. As the extension of follow-up period, both mean NIH thickness and NIH area progressively increased. (Mean NIH thickness; 52.2+/−35.0 (G1), 86.4+/−66.9 (G2), and 107.6+/−74.3μm (G3), p=0.0001. NIH area; 0.71+/−0.27 (G1), 1.14+/−0.71 (G2).1.38+/−0.89 mm 2 (G3), p=0.001, respectively). By contrast, the averaged rate of uncovered struts was significantly decreased (13.5%(G1), 11.9%(G2), 4.8%(G3), p=0.0051, respectively). Parameters of clinical background, including coronary risk factors, did not have influence on the neointimal coverage of struts, while full covered stent struts were frequently observed in relatively larger diameter stent than in smaller diameter stent.
CONCLUSION: Neointimal coverage of SES struts progressed as the extension of follow-up period. OCT assessment of implanted SES can determine neointima coverage, and may gives useful information for the discontinuation of dual antiplatelet therapy.