Ma. Kjelsberg et al., DESIGN-DEPENDENT VARIATIONS IN CORONARY STENT STENOSIS MEASURED AS PRECISELY BY ANGIOGRAPHY AS BY HISTOLOGY, The Journal of invasive cardiology, 10(3), 1998, pp. 142-150
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.