DESIGN-DEPENDENT VARIATIONS IN CORONARY STENT STENOSIS MEASURED AS PRECISELY BY ANGIOGRAPHY AS BY HISTOLOGY

Background Coronary stent restenosis is a growing clinical concern whi ch, because restenosis may vary with stent design, requires a validate d, accurate, and sensitive method of evaluation as new stents are deve loped. Histologic analysis of arterial cross sections, a highly accura te tool in animal models, has limited applicability in humans. Quantit ative coronary angiography, while commonly used in the clinical evalua tion of coronary interventions, has a controversial role as an adequat e measure of restenosis, and few studies have validated quantitative a ngiography in diseased arteries. We tested the hypothesis that in-sten t stenosis could be assessed as accurately by pre-mortem angiography a s by post-mortem histology, allowing angiographic discrimination of va riable late luminal loss provoked by stents of different designs. Meth ods and Results. Stent stenosis in porcine coronary arteries was asses sed by quantitative coronary angiography and histology at 3, 28 and 56 days. Four stainless steel stent designs were studied: a slotted tube configuration with or without a polymer wrap and a corrugated ring co nfiguration with or without a polymer coating. Although acute luminal gain (mean stent:artery ratio 1.07 +/- 0.01) and stent recoil (mean st ent diameter at follow-up 2.65 +/- 0.02 mm) were similar for all desig ns and time points, significant differences in late luminal loss were observed and were detected as accurately by angiography as by histolog y. At 28 days, the polymer wrapped slotted tube design resulted in a n early two-fold greater late loss than its bare metal counterpart (1.40 +/- 0.09 mm vs. 0.80 +/- 0.12 mm, p < .001 by angiography; 1.33 +/- 0 .10 mm vs. 0.67 +/- 0.06 mm, p < .0001 by histology), while there was no significant difference in 28 day late loss between the polymer coat ed and bare metal corrugated ring designs (p = NS by angiography or hi stology). Time point differences were also observed both angiographica lly and histologically, with marked progression of lumen loss between 3 and 28 days and slower but persistent progression between 28 and 56 days. Overall comparison of individual lumen diameter measurements for all stented arteries independent of design or duration of follow-up d emonstrated a precise correlation between angiography and histology (y = 0.96x +0.25,p < .0001, r(2) = 0.82). Conclusions. Coronary stents o f varied designs provoke markedly different degrees of late luminal lo ss, and these differences can be measured as accurately by quantitativ e angiography as by histologic analysis of arterial cross sections. Th is may be due to optimization of angiographic measurements by the conc entric nature of intimal thickening in stented arteries, and to struct ural rigidity imparted by the stent, preserving arterial lumen size fo r histologic analysis. Quantitative angiography, therefore, may repres ent an adequate endpoint in clinical trials comparing stent designs.