DALLAS, July 15 - A readily available, but underused, diagnostic test could help prevent unnecessary angioplasties, a procedure used to clean out blocked blood vessels to the heart, report researchers in today's Circulation, a journal of the American Heart Association.
Individuals who have chest pains or other symptoms of this condition, known as coronary heart disease, often undergo angiography so that doctors can determine the amount and location of artery blockage and decide whether treatment is necessary. Angiography provides a two-dimensional view of the artery and may not reliably predict whether arterial blood flow is impaired. When blood flow in the arteries is impaired, a heart attack can occur.
The study's authors recommend that angiography be followed by another test, called Doppler ultrasound, so that the velocity of blood flow can be closely measured and the size and location of arterial blockage can be more accurately evaluated.
Louis Heller, M.D., director of interventional cardiology at Winthrop-University Hospital in Mineola, N.Y., and lead author of the study, says use of intracoronary Doppler ultrasound tests dramatically increases the accuracy of determining whether a narrowed artery impairs blood flow, and consequently, whether it's necessary to undergo angioplasty.
Approximately 420,000 angioplasties are performed each year in the United States, but, according to researchers, 70 percent of those are not preceded by a test documenting ischemia, which is decreased blood flow resulting from the constriction or obstruction of an artery. Coronary angiograms alone do not reliably predict whether an intermediate stenosis -- 40 to 70 percent of the artery is blocked -- causes significant obstruction.
"You can't say that all of those angioplasties were unnecessary," Heller says. "But you can certainly assume that many were done without evidence for their indication."
In much the same way that a police officer uses a radar gun to determine how fast a car is traveling, physicians can use Doppler ultrasound to get a better idea of the flow rate of blood through the arteries. A picture of the artery alone may not be enough to determine the amount of blockage, just as a photo of a speeding car may not always prove how fast it is going.
Patients enrolled in the study underwent angiography with Doppler ultrasound and had exercise imaging stress testing, which provides an indication of ischemia, or decreased blood flow. The Doppler and imaging data agreed in 46 of 52 blockages (88 percent) in patients achieving their target heart rate on the stress test.
"Doppler ultrasound promises to help clarify whether a narrowed artery is causing a problem, and therefore, should reduce unnecessary procedures," Heller says. "For those patients who have chest pain, this technology can also open the door for relief from symptoms from an arterial narrowing that may not have been adequately assessed on the angiogram."
With the availability of Doppler ultrasound and its success, why isn't it more widely used?
"The major issue is third-party payer reimbursement, or the lack thereof," Heller said. "There is now a large body of data that clearly documents the utility of this test for coronary artery disease, and it's frustrating to me that third-party payers are not reimbursing for this vital procedure."
Co-authors of the study are Christopher Cates, M.D.; Jeffrey Popma, M.D.; Lawrence I. Deckelbaum, M.D.; James D. Joye, DO; Seth T. Dahlberg, M.D.; Bernard J. Villegas, M.D.; Anita Arnold, DO; Robert Kipperman, M.D.; W. Carter Grinstead, M.D.; Sharon Balcom, RN; Yunsheng Ma, M.D., MPH; Michael Cleman, M.D.; Richard M. Steingart, M.D.; and Jeffrey A. Leppo, M.D. Circulation is one of five journals published by the American Heart Association.
Media advisory: Dr. Heller can be reached at (516) 663-8856. (Please do not publish telephone numbers.)