Background: There is evidence that endothelial coverage of drug-eluting stents might be delayed or absent, a risk factor for late thrombotic events. We studied the effects of different drug-polymer-device iterations on endothelium-dependent coronary vasomotion. Systemic markers of endothelial inflammation were correlated with coronary vasomotor changes.
Methods and results: Patients with paclitaxel-eluting stents (n=11), sirolimus-eluting stents (n=21), biolimus A9-eluting stents (n=28), zotarolimus-eluting stents (n=10), and bare-metal stents (n=13) were studied 10, 9, 9, 9, and 12 months after implantation, respectively. Endothelium-dependent coronary vasomotion was tested proximally and distally to the stent and at a reference vessel segment during atrial pacing at increasing heart rates by quantitative coronary angiography. Indexes of platelet-monocyte binding and other biomarkers were studied in a subgroup of 19 patients. The baseline characteristics and hemodynamics of the patients in the different stent groups were comparable. Significant differences were observed across the 5 stent groups, concerning the vasomotion of segments proximal (P=0.006) and distal (P=0.003) to the stent. Normal vasomotion (vasodilatation) was maintained in the biolimus A9-eluting stent, zotarolimus-eluting stent, and bare-metal stent groups, whereas vasoconstriction was observed in the sirolimus-eluting stent and paclitaxel-eluting stent groups. Platelet-monocyte binding in whole blood showed a significant inverse correlation with vasomotion in reference but not in segments adjacent to the stent (r=-0.57; P=0.01).
Conclusions: Paclitaxel-eluting stents and sirolimus-eluting stents seem to cause endothelial dysfunction of the implanted vessel, whereas biolimus A9-eluting stents and zotarolimus-eluting stents behave more closely to bare-metal stents, with preserved endothelial vasomotor response. Coronary vasoconstriction was not associated with detectable systemic endothelial activation.