Abstract 4727: Specific Coronary Drug-Eluting Stents Interfere With Distal Microvascular Function After Single Stent Implantation
Introduction: Coronary endothelial dysfunction has been reported in patients nine months after drug eluting stent (DES) implantation, with the downstream vasculature at highest risk. However, the effects of single-implanted DES on distal vascular function have not been compared to date.
Hypothesis: Chronically single-implanted DES result in specific functional alterations of the distal circulation.
Methods: To compare the chronic effects of DES on distal vascular function, sirolimus-eluting stent (SES), paclitaxel eluting stent (PES) and bare metal stent (BMS) were implanted without prior vascular injury in eleven pigs for five weeks. Changes in distal vascular flow velocities induced by different doses of intracoronary administered bradykinin (BK) and nitrates were measured in vivo. In addition, specific components of distal vascular function were studied in vitro using wire myographs.
Results: Coronary flow velocities distal from the stent were not affected by either DES-type. However, in detailed in vitro studies, PES showed a reduced BK-response of only coronary micro-arteries after inhibition of NO-synthesis, as compared to BMS and SES (P<0.01 by repeated measures ANOVA). BK-induced vasodilatation, endothelin-1 induced vasoconstriction and vascular smooth muscle cell function were unaffected by PES. The key second messenger system of endothelium-dependent microvascular dilation to BK was unaffected by PES, since cyclic GMP production was unaltered. SES implantation did not affect any component of distal microvascular function. Surprisingly, conduit arterial function was not influenced by either DES-type.
Conclusions: In this study in healthy porcine coronary arteries, single-implanted SES and PES did not affect overall distal coronary function. However, PES altered distal endothelial microvascular vasodilation under conditions of reduced NO-bioavailability, already after five weeks. Therefore, this study raises the issue that specifically PES might be potentially harmful with regard to local cardiac perfusion downstream of the stentsite, particularly in vulnerable patients with marked endothelial dysfunction.