Coronary stent is known as an effective treatment in the intimal dissection after angioplasty and the prevention of restenosis. However, in-stent restenosis still remains a major concern in clinical stenting.

The Microstents were placed in 151 patients from May '96 to Aug '97 and performed follow-up coronary angiograms in 49 (32.5%) patients. To identify the clinical, angiographic and procedure-related variables that predict late restenosis within the stented artery, 49 patients (58±8 year:38 M, 11 F) were studied. Indications for stenting were 25 de novo (52.8%), 9 restenotic (18.7%), 8 suboptimal PTCA (16.7%) and 6 bail-out lesions (12.6%). All patients were treated with aspirin and ticlopidine for one month after stenting. The follow-up angiograms were obtained at 5±3 months and variables of 13 patients with restenosis were compared with those of 36 patients without restenosis.

The in-stent restenosis rate was 26.5%. Univariate logistic regression analysis was used to determine how in-stent restenosis was influenced. Clinical diagnosis, presence of risk factors, lipid profiles, numbers of involved vessels, target arteries, lesion length, lesion types, stent length, maximal inflation pressure, predilation balloon size, reference vascular diameter, minimal luminal diameter, and stent to artery diameter ratio were analyzed. Among these variables, only lesion length before stent implantation was a predictor for in-stent restenosis (19.9±11.1 mm vs. 10.9±7.3 mm, p=.017).

Lesion length before Microstent II implantation is the single predictor of late in-stent restenosis.