St. Jude's new device
can help spot severity
of blood flow blockages

Device Shows When Narrowing Arteries Are Really Dangerous

September 29, 2009
by Brendon Nafziger, DOTmed News Associate Editor
Technology that detects whether arterial narrowing is life-threatening by measuring blood flow blockage could help doctors avoid unnecessary stenting and cut the risk of serious heart problems, such as cardiac arrest and death, by almost a third, according to a statement issued by St. Jude Medical Systems.

The device, called the PressureWire Aegis system, is one of the first to give "physiologic information not just anatomical information" about stenosis, or narrowing of the arteries, Mark Zolnick, MD, a cardiologist affiliated with the New Mexico Heart Institute, tells DOTmed News.

The PressureWire measures fractional flow reserve (FFR), or how serious blood flow obstructions in the coronary arteries are, helping doctors to understand whether the stenosis needs treatment with a stent, or can be safely left alone.

"Our eyeball estimation of the severity of blockages is not that good," says Dr. Zolnick, who was one of the first people to use the device at CHRISTUS ST. Vincent Medical Center, in Santa Fe, NM. "It can't tell us if the stenosis is flow-limiting," requiring intervention, he says.

The report on the device, called the FAME (Fractional Flow Reserve vs. Angiography in Multivessel Evaluation) trial, was delivered at this month's Transcatheter Cardiovascular Therapeutics (TCT) conference in San Francisco. FAME included more than 1,000 patients, and compared outcomes from using PressureWire with outcomes from angiography alone.

The study reported around 34 percent fewer major adverse cardiac events, such as heart attack and death, for those who had been screened first with PressureWire. It also said there were savings in costs associated with materials and surgery of around 11 percent.

The FAME report presented at TCT was a two-year follow up to the original study on the device published last January in the New England Journal of Medicine.

Dr. Zolnick says the main cost-savings come from avoiding unnecessary stent placement. And the error rate is extremely low. In the study, of the more than 1,000 lesions investigated where the FFR was normal, and treatment not recommended, only one went on to cause a heart attack, according to Dr. Zolnick. "As you know," he says, "a lot of the lesions that cause myocardial infarctions are not hemodynamically significant until they somehow rupture. This [device] doesn't tell us if the stenosis is prone to rupture in the future, but rather how narrow it is and how hemodynamically significant."

The device, which can also be used to guide stents, works in conjunction with a blood-flow monitoring system produced by GE.