Based on findings of a recent study researchers from Sweden say they have found that implantation of a sirolimus-eluting stent is associated with coronary vasoconstriction in areas adjacent to the treated vessel that is not seen with bare metal stents.
Sirolimus-eluting stents are widely used for percutaneous coronary interventions because of their excellent long-term clinical and angiographic outcome, however, recent concerns have been raised that the stents could lead to increased rates of stent thrombosis due to delayed or absent endothelialization.
AdvertisementResearchers compared endothelial function and coronary vasomotor response to exercise in 14 patients fitted with sirolimus-eluting stents and 11 control patients receiving bare metal stents. It was observed that after 6 months, the reference vessel showed an increase in exercise-induced vasodilation in both groups, with a mean increase in diameter of 13%, and no vasomotion in the stented vessel segments. In adjacent segments that were proximal and distal to the bare metal stent there were also increases in exercise-induced vasodilation of 15% and 17%, respectively. In contrast, exercise-induced vasoconstriction - indicating endothelial dysfunction - occurred with the sirolimus-eluting stent at these locations, with decreases in vessel diameter of 12% and 15%, respectively (p<0.001 vs controls). Vasodilatory capacity was preserved, with sublingual nitroglycerin associated with maximal vasodilation of these vessel segments in both groups.
Researchers are of the opinion that Paradoxic vasoconstriction in a vessel segment not subjected to percutaneous transluminal coronary angioplasty barotrauma may be due to diffusion of the antiproliferative drug from the stent to the peri-stent region, inducing endothelial dysfunction. However some are of the opinion that inadequate endothelial coverage could lead to insufficient nitric oxide to promote normal vasodilation with exercise. In conclusion researchers say that they will not be able to come to any positive finding, until further studies are done in this field.
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