CHICAGO - Two new studies find shortfalls in the Food and Drug Administration's approval process for heart devices such as pacemakers and stents.

Safety targets often weren't clearly spelled out in the research submitted by device-makers, and important patient information was missing, according to one study conducted by researchers from the FDA and Boston's Beth Israel Deaconess Medical Center.

A separate analysis by researchers at the University of California, San Francisco, found heart devices frequently got the FDA's blessing based on research done outside the United States in small groups of patients. Many device studies lacked standards most scientists expect: randomization and a clear goal.

Jeffrey Shuren, the FDA's acting device-center director, said the agency was taking a close look at its device program and making changes. It wants manufacturers to adhere to tougher research guidelines that will be out in 2010, Shuren said.

The FDA, the nation's chief watchdog on device safety, approves products ranging from wrinkle fillers to artificial knees. Heart devices fall into a category of high-risk devices that require the toughest review before they can be marketed. They include implantable defibrillators, valves, and stents, which are tiny mesh-metal tubes used to prop open arteries.

The new studies, published in separate medical journals, cap a year of scrutiny and criticism for the FDA's medical-devices division. In August, the division head resigned, months after scientists under his leadership alleged they were pressured to approve certain products. The year began with congressional investigators saying the FDA should take immediate steps to make sure the riskiest devices are approved through the most stringent process.

The new studies did not examine the safety of the approved devices. Nor did they look for differences in the approval process for items that were later recalled.

One of the new studies, published online yesterday in the American Journal of Therapeutics, found about 40 percent of pivotal studies lacked precise targets for how safety would be measured.

Studies also failed to fully account for what happened to all patients enrolled in the research and omitted important information on patients such as how many had heart disease or diabetes. Several FDA staffers were authors of the analysis, which looked at the research behind 88 heart and blood-vessel devices.

The second study appears in today's Journal of the American Medical Association. Researchers from the University of California, San Francisco, examined summaries of the research behind 78 heart and blood-vessel devices. It found that many devices were approved based on small studies - 300 patients on average - and two-thirds were approved with results of just one study.

Both studies looked at "premarket approvals" of devices approved from 2000-07.