Problems with Coated Stents

About a million eluting stents are placed in patients’ coronary arteries annually in the USA . An eluting stent is a tiny metal tube that’s coated on the inside with a drug that prevents clotting, which is put into someone with a partially-blocked coronary artery due to atherosclerosis. These devices have been marketed based on relatively short-term studies that show they hold open stenosed arteries and don’t seem to clot up. But now two Swiss reports at a European cardiac convention, which analyzed available data from published studies (i.e. meta-analyses), have caused some consternation.

One stent was coated with sirolimus (Cypher®, an immunosupressant), the other with paclitaxel (Taxus®, an anti-cancer drug); both were compared with bare metal stents in the 26 published studies. Analysis of long-term results showed that, while both coated stent types reduced the re-stenosis rate, they led to increased non-cardiac mortality. The risk was 38% higher with sirolimus and 16% higher with paclitaxel stents, compared to bare metal stents.

The experts at the congress were divided over the importance of these findings. One said the data are “not convincing, but they are disconcerting”. Another felt that one reason for the late deaths might be thrombosis in the coated stents because the drugs had not permitted the endothelium (the inner lining of arteries) to re-canalize the stents. Someone else noted that only half the cases had been taking antiplatelet therapy after the first few months after surgery; it’s normally advised that it should be continued for a year, unless there are bleeding problems.

These reports will probably give pause to the cardiac surgeons about to place stents. At all events, they will follow their patients more carefully, to be able to act in time if there are ‘late’ problems.