Drug-eluting stents are useful for preventing restenosis, but the patho-physiological processes involved in the proliferative response after implantation are still not known in detail. The aim of this study is to compare the coronary vascular histomorphometry after implanting drug-eluting stents and bare metal stents in a swine model.
Sixty stents were randomly implanted in 20 Large White female pigs with a ratio of baremetal/drug-eluting stents of 1:2. After 28 days, euthanasia and histomorphometry were performed. We defined the vessel injury score in accordance to whether the internal elastic lamina was intact or ruptured.
There were no differences between drug-eluting stents and bare metal stents in the intact internal elastic lamina group regarding neointimal area or%restenosis (1.3 [1.1-2.2]) vs 2.0 [1.3-2.5] mm<sup>2sup>; P=.6; and 14.0 [12.1-20.8] vs 22.2 [14.1-23.3]%; P=.5). We assessed statistically significant differences for the ruptured internal elastic lamina group, (neointimal area 1.2 [0.8-2.0] vs 2.9 [2.3-3.7] mm<sup>2sup>; P=.001 and%restenosis 16.63 [11.2-23.5] vs 30.4 [26.4-45.7]%; P=.001).
In our swine model, we did not find any differences between proliferative response of drug-eluting stents and bare metal stents when the internal elastic lamina is intact; differences are only found when vascular injury is deeper.
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