Such stents are used to open blocked heart arteries but concerns have arisen over clot formation in some patients several years after implantation.

The guidelines outline the agency's recommendations for premarket clinical evaluation and post-market studies, which the FDA said might provide data to better address potential safety concerns.

Each year in the United States, approximately 1 million patients undergo procedures to treat coronary atherosclerosis, also known as hardening or blockages of the heart arteries -- a condition that can cause angina and heart attacks, the FDA said. Some 650,000 of such patients are treated with drug-eluting stents that are coated with a medication that prevents the growth of scar tissue.

The draft guidance is available at http://www.fda.gov/cdrh/ode/guidance/6255.html.