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

Background. Coronary stent restenosis is a growing clinical concern wh ich, because restenosis may vary with stent design, requires a validat ed, accurate, and sensitive method of evaluation as new stents are dev eloped. Histologic analysis of arterial cross sections, a highly accur ate tool in animal models, has limited applicability in humans. Quanti tative coronary angiography, while commonly used in the clinical evalu ation of coronary interventions, has a controversial role as an adequa te measure of restenosis, and few studies have validated quantitative angiography in diseased arteries. We tested the hypothesis that in-ste nt stenosis could be assessed as accurately by pre-mortem angiography as by post-mortem histology, allowing angiographic discrimination of v ariable late luminal loss provoked by stents of different designs. Met hods and Results. Stent stenosis in porcine coronary arteries was asse ssed by quantitative coronary angiography and histology at 3, 28 and 5 6 days. Four stainless steel stent designs were studied: a slotted tub e configuration with or without a polymer wrap and a corrugated ring c onfiguration with or without a polymer coating. Although acute luminal gain (mean stent:artery ratio 1.07 +/- 0.01) and stent recoil (mean s tent diameter at follow-up 2.65 +/- 0.02 mm) were similar for all desi gns and time points, significant differences in late luminal loss were observed and were detected as accurately by angiography as by histolo gy. At 28 days, the polymer wrapped slotted tube design resulted in a nearly two-fold greater late loss than its bare metal counterpart (1.4 0 +/- 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 coa ted and bare metal corrugated ring designs (p = NS by angiography or h istology). Time point differences were also observed both angiographic ally 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 fo r all stented arteries independent of design or duration of follow-up demonstrated a precise correlation between angiography and histology C y = 0.96x +0.25, p < .0001, r(2) = 0.82). Conclusions. Coronary stents of varied designs provoke markedly different degrees of late luminal loss, and these differences can be measured as accurately by quantitat ive angiography as by histologic analysis of arterial cross sections. This may be due to optimization of angiographic measurements by the co ncentric nature of intimal thickening in stented arteries, and to stru ctural rigidity imparted by the stent, preserving arterial lumen size for histologic analysis. Quantitative angiography, therefore, may repr esent an adequate endpoint in clinical trials comparing stent designs.