Furthermore, the researchers said, about one-third of the new stents were placed in patients with clinical characteristics for which such stent use has not yet been approved by the Food and Drug Administration (FDA). However, the researchers said that their finding of a high rate of "off-label" usage should be seen more as an impetus for further clinical trials rather than an immediate safety issue, since cardiologists have been placing traditional stents for more than 10 years and are comfortable with the procedure.
Stents are tiny mesh tubes that are inserted into the site of a blockage in a coronary artery that has been opened during balloon angioplasty. However, a principal complication of the procedure has been the high rate of treated arteries becoming blocked again, a process known as restenosis.
In an attempt to improve stents to keep treated arteries open, stent manufacturers coated them with a chemotherapeutic agent that limits the formation of scar tissue inside the artery. So far, clinical trials have shown that these new stents can reduce the restenosis rate to single digits from the 20 to 30 percent rate of the older stents. The first drug-eluting stent received FDA approval in April, 2003.
"Drug-eluting stents are truly breakthrough products in treating coronary artery disease, and in our analysis of the early trends of the their use, we found disparities in terms of age, race and socio-economic factors," said Duke cardiologist Sunil Rao, M.D., who presented the results of the Duke analysis Nov. 10, 2004, at the American Heart Association's annual scientific sessions in New Orleans.