OBJECTIVETo evaluate the short- and long-term prevalence of persistent uncovered struts and in-stent thrombus after sirolimus-eluting stent (SES) implantation by optical coherence tomography (OCT).

METHODSOCT was performed for 31 SES in 21 patients at 3 months and for 30 SES in 21 patients at 2 years post SES implantation. Thickness of new intima inside each strut was measured and thickness equal to 0 microm was defined as an uncovered strut. Existence of in-stent thrombus was also evaluated.

RESULTSA total of 4545 struts and 3707 struts were evaluated at 3 months and at 2 years post SES implantation, respectively. New intima at 2 years was significantly thicker than that at 3 months [(71 +/- 93) microm vs. (29 +/- 41) microm, P < 0.01]. Percent of uncovered struts at 2 years was significantly lower than that at 3 months (5% vs. 15%, P < 0.01). Prevalence of uncovered struts was similar at 2 years and at 3 months (81% vs.95%, P > 0.05). Subclinical thrombus was recognized in 14% patients at 3 months and 2 years post SES implantation.

CONCLUSIONSNeointimal coverage inside the SES is a continuous process and the number of uncovered struts decreased from 3 months to 2 years after SES implantation. Few uncovered struts could still be visualized in the majority of patients at 2 years post SES implantation.