Abstract

Objective: A bimodal distribution of measures of restenosis has been demonstrated at 6-8 months following bare metal stent implantation. Drug-eluting stent (DES) therapy has attenuated the impact of certain factors (e.g. diabetes) on restenosis but its effect on the distribution of indices of restenosis is not known. We performed detailed analysis of the metrics of restenosis indices following DES implantation.

Design, settings, patients: Prospective observational study of patients undergoing DES implantation (Cypher, sirolimus-eluting stent; or Taxus, paclitaxel-eluting stent) at two German centres, with repeat angiography scheduled at 6-8 months after coronary stenting.

Main outcome measures: In-stent late luminal loss (LLL) and in-segment percentage diameter stenosis (%DS) as determined by quantitative coronary angiography at re-catheterization.

Results: Paired cineangiograms were available for 2057 patients. Overall mean LLL was 0.31±0.50 mm; mean %DS was 30.3±15.7. Distribution of both LLL and %DS differed significantly from normal (Kolmogorov-Smirnov test; p<0.001 for each). For both parameters a mixed distribution better described the data (likelihood ratio test with 3df; p<0.001 for each). This consisted of two normally-distributed sub-populations with means of 0.10±0.25 mm and 0.69±0.60 mm for LLL, and means of 22.2±8.6 and 40.1±16.6 for %DS. No effect of stent type on distribution patterns was evident when data was analyzed according to type of stent implanted.

Conclusions: Late loss and percentage diameter stenosis at follow-up angiography post DES implantation have a complex mixed distribution that may be accurately represented by a bimodal distribution model. The introduction of DES therapy has not resulted in elimination of a variable propensity to restenosis among subpopulations of stented lesions.