Recent reports of drug-coated stents causing life-threatening blood clots need not alarm heart patients since most Canadians would undergo preventive drug therapy following stent procedures, the Heart and Stroke Foundation says.

But the jury is still out on the question, said Dr. Beth Abramson of the Heart and Stroke Foundation on Tuesday.

"In Canada and specifically Ontario, it is less of an individual issue as many patients, especially those over the age of 65, are covered and are often prescribed two Aspirin-like medications."

U.S. medical journals have examined cases in which patients implanted with drug-coated stents — tiny mesh tubes that force open a clogged artery — are up to five times more likely to experience blood clotting not long after their operations.

Those clots almost always cause a heart attack because many U.S. patients do not receive medication to stop the problem. The U.S. Food and Drug Administration is reviewing the use of drug-coated stents.

In much of Canada, though, doctors usually prescribe patients with powerful anti-clotting drugs over the long term and usually for at least a year.

Drug-coated stents became popular around 2002 because the original stents, while helpful in keeping vessel walls open, failed to prevent lesions from forming and slightly cramping up the passageway.

But the trouble with the stents coated with drugs, as opposed to the bare stainless steel variety, seems to be that the drug coating on the device not only interferes with the scarring around the tube known as "restenosis," but it also inhibits growth of normal tissue.

"You're also preventing the lining of the blood vessel to grow as well, and as a consequence, the environment is very sticky without a blood vessel lining around the stent," Abramson said. In rare cases, a clot could form around that "sticky" area.

Rare as the problem may be, it is still worrisome to the millions around the world who have undergone the procedure.

Abramson said people should not be overly concerned if they already have a drug-coated stent in place. But patients should remember "newer and more expensive therapies are not always the way to go."

"It's important to evaluate newer technologies but make sure patients are on medications and making lifestyle changes."