Electron-beam computed tomography - a more accurate replacement for coronary catheterizations

Electron-beam computed tomography (EBCT) is more accurate than conventional catheter angiography for detecting a dangerous congenital heart abnormality that could cause sudden death, according to research by a Saint Louis University radiologist published last month in Catheterization and Cardiovascular Interventions: Journal of the Society for Cardiovascular Angiography and Interventions.

Esat Memisoglu (AY-sot May-me-show-loo), M.D., assistant professor of radiology at Saint Louis University School of Medicine, and his team - which included another radiologist and several cardiologists - studied 28 adults at a heart hospital and imaging center in Istanbul, Turkey, who had undergone conventional X-ray angiography for chest pain or shortness of breath and then later underwent an EBCT.

In half of the patients, angiography showed a congenital abnormality - for example, a left coronary artery originating from the right side of the aorta, or vice versa. EBCT also detected the abnormalities, but in more than a third of the cases, it was able to provide information the angiography could not. Specifically, it could confidently determine whether the artery traveled perilously between the aorta and pulmonary artery, putting that patient at risk for a heart attack or sudden death, Memisoglu says.

"The most crucial clinical question is whether the artery is coursing between the aorta and pulmonary artery. Angiography did not always give us the correct answer, but it was very easy to tell using EBCT," Memisoglu says.

Traditional catheter angiography, an invasive two-dimensional projectional X-ray technique that involves passing a catheter through a patient's groin artery to the heart vessels, is commonly used when physical examinations and other non-invasive tests are found to be negative in younger patients who experience chest pain or fainting during strenuous physical activity.

However, catheter angiography "can lead to ambiguities because of its in defining complex vascular anatomy," Memisoglu says.

In contrast, EBCT, which uses a specialized stationary X-ray tube and a high-resolution detector system, enables doctors to capture "practically blur-free" cross-sectional images of the beating heart, says Memisoglu. Because of its speed in capturing images - the study is completed in fewer than 30 seconds - patients don't need medication to slow their heart rate.

EBCT, along with multi-slice computed tomography (MSCT) - which features a moving X-ray tube but is comparable to EBCT in diagnosis - produces stunning three-dimensional images of the heart that help radiologists detect congenital defects that otherwise might not have been picked up. EBCT and MSCT can also rule out the presence of significant coronary artery blockages with a high degree of accuracy. "Up to 40 percent of all patients in the U.S. who go through invasive catheter angiography do not end up needing revascularization treatment, such as stenting or bypass surgery. That means a major role for MSCT and EBCT would be gatekeeping - telling us which patients would benefit most from an invasive procedure," Memisoglu says.

Memisoglu also sees an economic advantage to using EBCT or MSCT scans in place of catheter angiography.

"Liberal use of coronary catheterizations are costing taxpayers millions of dollars, driving the cost of medical insurance and creating a burden on the economy," he says.

He predicts non-invasive scans - such as EBCT, MSCT and magnetic resonance imaging (MRI) - will one day replace catheter angiography entirely to detect heart vessel blockages and congenital abnormalities; conventional catheter angiography will then be used for treatment only, he suspects.

"We don't want to block access to catheter angiography for patients who really need it," Memisoglu says. "But EBCT and MSCT can help avert the unnecessary physical and psychological consequences of an invasive procedure."

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