In much of the world (but not in the U.S.,) drug-coated stents are avoided by cardiologists because of their high cost. To compensate for the inability to use these stents, many cardiologists outside of the U.S. have taken to administering sirolimus (also called rapamycin, one of the drugs used for coating stents) in pill form to their patients who receive bare-metal stents. Giving the drug orally is far cheaper than coating the stents with the same drug. Until now, however, there wasn't much evidence that orally administered sirolimus actually prevents restenosis. ( Click here for a review of the problem of restenosis.)
To study whether this practice does indeed reduce re-stenosis in patients receiving non-drug-coated stents, investigators from Europe conducted the OSIRIS trial. The results of this trial were published in the August 9 issue of Circulation. It appears that oral sirolimus is significantly effective.
In the OSIRIS trial, 300 patients who received bare-metal stents were randomized to take either a placebo, or various doses of oral sirolimus (a loading dose followed by a maintenance dose for 7 days.) After 6 months, the incidence of restenosis was signficantly reduced - by 48% - in the patients who received 1 week of high-dose oral sirolimus. There was no increase in major complications among patients taking sirolimus.
What does this study mean?
For one thing, these results indicate that companies that had hoped, eventually, to sell a lot of drug-coated stents in Europe and Canada probably ought to recalculate their business models. While oral sirolimus, as administered in the OSIRIS trial, may not be as effective in preventing restenosis as drug-coated stents, it does seem to be a major step in the right direction. It is unlikely that orally administered drugs will replace drug-coated stents anytime soon in the U.S., but we can expect to see future studies evaluating whether adding oral drug therapy to drug-coated stents can further improve results.
