Indication of long-term endothelial dysfunction after sirolimus-eluting stent implantation

Aims: Endothetial dysfunction has been related both to progression of atherosclerotic disease and to future cardiovascular events. We assessed local epicardial endothelial function 6 months after sirolimus-eluting stent (SES) or bare metal stent (BS) implantation. Methods and results: In 12 patients (seven SES, five BS), endothelium-dependent vasomotion of a coronary segment 15 mm in length, starting 2 mm distal to the stent, was assessed with quantitative coronary angiography immediately after the procedure and at 6 months follow-up, after intracoronary infusion of acetylcholine. Intravascular ultrasound (IVUS) was performed and coronary flow reserve (CFR) assessed in all patients. At follow-up significant vasoconstriction was seen in SES (median 32% diameter reduction from baseline) but not in BS (median 2% reduction) patients after acetylcholine infusion (P = 0.03 for SES vs. BS); endothelium-independent vasodilatation to nitrates did not differ significantly between groups (20% SES, 5% BS, P = 0.14). IVUS revealed no late unhealed dissections and CFR was comparable between groups (SES 3.1 vs. BS 3.2, n.s.). Conclusion: SES implantation may have an adverse effect on local endothelium-dependent vasomotor responses compared with BS implantation at 6 months. Long-term clinical consequences of this observation are still unknown.