Drug-Eluting Stents May Impair Growth of Collateral Vessels

Study suggests that collateral vessel formation may be lower than with bare-metal stents

FRIDAY, Jan. 5 (HealthDay News) -- As the U.S. Food and Drug Administration evaluates the safety of drug-eluting stents, a new study suggests that such stents may impair collateral vessel formation in the months after implantation compared with bare-metal stents, according to a report in the Jan. 2 issue of the Journal of the American College of Cardiology.

Pascal Meier, M.D., of University Hospital in Bern, Switzerland, and colleagues compared coronary collateral function among 120 patients six months after bare-metal stent or drug-eluting stent implantation.

There were no differences in the groups in regards to in-stent stenosis severity and/or duration of follow-up. However, the collateral flow index was reduced in the drug-eluting stent group compared to bare-metal stent group (0.154 versus 0.224). Patients with drug-eluting stents were more likely to have insufficient vessel formation to prevent ST-segment elevation during balloon occlusion (50 of 60 patients) than those in the bare-stent group (33 of 60).

The researchers hypothesize that drug-eluting stents have an inhibitory effect on the production of cytokines, chemotactic proteins and growth factors, and as a result, may impair coronary collateral growth. "Although it is still of largely theoretical concern, should abrupt late occlusion occur after drug-eluting stent, the normal collateral protection would be impaired to some degree, with more ischemia potentially permitting a larger ischemic insult and higher mortality risk than would otherwise occur," writes Morton J. Kern, M.D., of the University of California-Irvine, in an accompanying editorial.

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