Drug-coated stents increase the risk of blood clots

Sep 5 2006

Heart experts attending the World Congress of Cardiology have expressed their concerns over the long-term safety record of drug-coated stents.

It seems that studies presented at the conference in Barcelona this week have raised new concerns about the risks associated with the drug-coated stents.

The drug-coated heart stents, tiny metal-mesh tubes used to prop open coronary arteries, were introduced in 2000 as an improvement on bare-metal stents but experts say in some cases they may encourage potentially fatal blood clots.

They have raised their concern as almost 6 million people worldwide now have the drug-lined versions.

A study by researchers in Holland and Switzerland which monitored 8,146 patients, found that recipients of drug-coated stents had an increased risk of potentially fatal thrombosis, or blood clots.

Two other Swiss studies, which carried out an analysis of other studies on the issue also found that first-generation drug-coated stents had a greater link to thrombosis compared to bare metal stents during the first three years following stent implantation.

The drug coated stents are meant to keep the arteries open after they have been cleared of fatty deposits and are often credited with saving patients from future heart attacks or bypass surgery.

With the bare metal stents, heart tissue grows naturally to cover the stent, providing a natural biological lining but sometimes a thick growth of tissue develops which is undesirable.

The drugs on the new devices prevent too much tissue growth but sometimes they work so well that they have prevented a protective cell layer from growing, leaving exposed metal, which can act as a clot magnet.

The drug-coated stents are now used in most procedures in wealthy countries such as the United States and Switzerland, but some cardiologists say they will be more cautious about their use in future.

Dr. Steven Nissen, president of the American College of Cardiology and director of cardiology at the Cleveland Clinic says the information is explosive and of concern but he believes there is already a shift in the U.S. away from using drug-coated stents in favour of their uncoated predecessors.

Some medical experts have expressed concern that the financial implications of reducing the use of the profitable drug-coated stents are taking priority over improving patients' health.

Drug coated stents cost around three times more than bare metal ones and the market is thought to be worth more than $5 billion a year.

Dr. Christoph Kaiser of Basel's University Hospital, who first raised concern over the drug-coated stents in 2005, said new evidence from an 18-month patient follow-up program suggested they may be worthwhile in only one in three cases.

Dr. Salim Yusef, professor of medicine and director of cardiology at McMaster University, Hamilton, Canada says it is a terrible indictment that despite six million of these procedures having been done there is no long-term safety data on them.

The new findings however are not expected to dramatically alter the use of drug-coated stents in the immediate future.