Abstract 1424: Taxus but not Cypher Drug Eluting Stents induce Endothelial Dysfunction in the Distal Coronary Microvasculature
Drug eluting stents (DES) are associated with epicardial endothelial dysfunction (acetylcoline) both proximal and distal to the stent as late as 6 months after implantation in humans. The effects of DES on the distal microvasculature have not been studied to date. Consequently, we assessed in vitro microvascular function 5 weeks following implantation of Taxus and Cypher versus a bare metal stent (BMS) in swine (~75 kg). Stents were implanted with a balloon/artery ratio of 1.1 in the three major coronary arteries using QCA. Each swine (N=5/group) received all 3 stents. At follow up, microvascular endothelial -dependent dilation to bradykinin (BK) and -independent to sodium nitroprusside (SNP, NO donor) were evaluated in resistance arteries (~300 μm) isolated and mounted in a wire myograph. In all groups, BK induced vasodilation in a concentration-dependent manner. However, Taxus resulted in impaired BK-induced relaxation as compared to BMS and Cypher (Fig⇓). NO blockade by L-NAME reduced BK-induced response in a comparable way in all stents suggesting that NO contribution to the BK-induced dilation was similar between groups. Importantly, the smooth muscle cell function was similar in all groups as shown by the SNP data. In conclusion, Taxus but not Cypher or BMS results in impaired BK-induced dilation in the distal microvasculature. Since the contribution of the NO pathway was similar, and prostanoids were shown not to contribute to this response in porcine microcirculation, this suggests that the impairment in vasodilation is mediated via a withdrawal of the EDHF pathway. This study supports the concept that DES have not only local but also regional effects on the vascular function.