Pet Scanning Better for Heart Disease Diagnosis, Management

BUFFALO, N.Y. -- Using positron emission tomography (PET) scanning rather than other types of imaging as the first tool to diagnose heart-vessel blockages is more accurate, less invasive and saves dollars, a study by University at Buffalo researchers has shown.

The research findings were presented today (March 8, 2005) at the American College of Cardiology's Annual Scientific Session in Orlando, Fla.

Results of the study provide a rationale for PET scanning to become the initial diagnostic test for assessing a patient's risk of heart attack, say lead researchers Michael Merhige, M.D., UB clinical associate professor of nuclear medicine, and Joseph Oliverio, UB clinical instructor of nuclear medicine who is a certified nuclear medicine technologist. Both also are affiliated with the Heart Center of Niagara at Niagara Falls Memorial Medical Center.

"Because PET scanning is more accurate and provides a clearer picture of the state of the heart, it could decrease the use of angiograms and bypass surgery by more than 50 percent if used as the first-line test with patients," said Merhige. "All too often it is the last test.

"Currently cardiologists conduct a range of tests, including stress tests and an imaging procedure called single photon emission computed topography, or SPECT," Merhige said. "False readings from SPECT often put patients through angiograms that turn out to be normal. PET avoids most false positives, as well as false negatives, because the images have higher resolution."

An angiogram is a moderately invasive procedure that involves threading a catheter through a vein in the leg and injecting a special dye visible on an X-ray into the circulatory system near the heart. Blood flow then can be tracked and blockages detected by observing the dispersion of the dye. An angiogram costs around $4,800, the researchers calculated.

PET currently is used clinically primarily for cancer patients. A Web site advocating the use of PET scanning in clinical cardiology lists only 25 sites in the U.S. that perform coronary PET scanning, two of which are in Western New York.

Because little peer-reviewed literature exists comparing PET to SPECT, the current standard, coronary PET scanning is considered experimental, although it has been used in Western New York for 10 years, Oliverio said.

To help bring coronary PET scanning into the clinical mainstream, Merhige, Oliverio and colleagues compared cost and outcome data of 102 patients who were imaged with SPECT with data from 2,159 patients who had PET and were matched by extent of coronary artery disease. Merhige also compared data from the 102 SPECT patients with data from a national multi-center trial to confirm that his outcomes were valid.

Results showed that both the rate of heart attack and cardiac death were significantly lower after one year in patients managed by PET. The number of angiograms, balloon angioplasty with stenting and coronary bypass surgery also was significantly lower in the PET-managed patients. The average cost to manage a patient with coronary artery disease in this study was 25 percent lower in the PET group.

"Bypass surgery and angioplasty with stenting certainly will need to be used in some patients," said Merhige, "but we feel that many are done unnecessarily when medical management could be an alternative.

"The problem is that significant lifestyle changes -- very low-fat diet, exercise, cholesterol-lowering drugs and stress management -- are essential for successful medical management," Merhige added. "For some patients, surgery seems like a quicker option, when it actually only addresses symptoms, not the underlying disease process."

Additional researchers on the study were Victoria Shannon, registered nurse.; George Watson, UB medical student; Kimberly Smith, nurse practitioner; Shannon Frank, nuclear medical technician and UB clinical instructor of biotechnical and clinical laboratory sciences; Gary Stern, M.D., a former medical student now with Western New York Cardiology; David Avino, M.D., UB clinical assistant professor of medicine, and Anthony Perna, M.D., UB clinical instructor of medicine. Shannon and Smith are employed by Merhige's practice.