Some Drug Coated Stents May be Safer Than OthersSep 17, 2007 | Parker Waichman LLP, LLP
The safety of drug coated stents could be affected by the type of drug that coats the device. A new study has found that stents coated with the medication siromilus appear to be slightly safer than those coated with another drug called paclitaxel. However, because the study looked at a wide variety of patients, the authors say that it is not yet possible to say that the siromilus-eluting stents are definitively safer.
Drug coated stents were developed as a way to keep blood vessels open after an angioplasty. Currently, there are two Food and Drug Adminstration approved drug eluting stents available in the US. Johnson & Johnson’s Cypher Stent emits sirolimus, while Boston Scientific’s Taxus Stent emits paclitaxel. Stents are lattice-like devices that act like scaffolding to hold a blood vessel open. The drug coating is supposed to keep scar tissue from closing the artery, a common problem with the bare metal version. In 2006, the safety of drug coated stents was called into question when the Cleveland Clinic published an analysis of fourteen stent studies covering more than 6,000 patients that found those with drug coated stents were four to five times more likely to suffer from blood clots than those implanted with bare metal stents. Since then, use of the drug coated stents has dropped dramatically.
This latest study was conducted by the University of Bern in Switzerland. The researchers analyzed 38 stent trials involving more than 18,000 patients. The study only looked at the incidence of new heart attacks and restenosis – a re-blockage of the reopened artery – following the implantation of a stent. Patients receiving a stent coated with siromilus had 19-percent fewer heart attacks than those receiving a bare metal stent, while those who received paclitaxel-eluting stents had 17-percent fewer heart attacks.
But the analysis included such a wide variety of patients that the findings cannot be considered conclusive. For instance, the study did not differentiate between patients who were put on a regimen of clot-reducing medication like Plavix, and those who were not. After the Cleveland Clinic published its study last year, it was recommended that patients who received drug-eluting stints take such medication. Patients on Plavix and similar drugs would skewer the study results in a way that make drug coated stents appear more effective than bare metal stents, the authors conceded. In fact, some researchers thought that the lower heart attack rate in drug eluting stents could be attributed to the increased use of Plavix in these patients. The study also did not differentiate between patients who might have had previous heart attacks, another factor that is thought to increase the possible dangers associated with drug coated stents.
What the study indicates, however, is the need for more research to be done on drug coated stents. None of the studies – both favorable and unfavorable – have been conclusive so far. Right now, patients receiving drug coated stents face a great deal of uncertainty, making them human guinea pigs. Only more study into the safety of these devices will determine when, or if, drug coated stents are an appropriate choice for a patient.