New test detects heart disease--but more study needed

NEW YORK, Jun 30 (Reuters Health) - Close on the heels of a report favoring the use of a new test, electron beam computed tomography (EBCT), for evaluating chest pain comes the report of an expert panel opposing its widespread use.

"Electron beam computed tomography is an accurate and noninvasive alternative to traditional stress testing for the detection of (coronary artery disease) in symptomatic patients," according to Dr. David Shavelle from the Harbor-UCLA Research and Education Institute in Torrance, California and associates.

But Dr. Robert O'Rourke and the Writing Group of the American College of Cardiology/American Heart Association (ACC/AHA) Expert Consensus Document see it differently. "The majority of the members of the Writing Group would not recommend EBCT for diagnosing (coronary artery disease) because of its low specificity (high percentage of false-positive results)," they write, "which can result in additional expensive and unnecessary testing to rule out (coronary artery disease)."

Both reports are published in the July issue of the Journal of the American College of Cardiology.

Shavelle's group compared EBCT with other traditional methods for diagnosing CAD in 97 patients with chest pain. The researchers used angiography--where a dye is injected to outline the arteries--as the gold standard for evaluating the other methods.

EBCT was positive in 96% of the patients who had coronary artery disease, the authors report. But because EBCT was also positive in nearly half the patients without narrowed heart arteries (in other words, was false-positive), its overall accuracy in diagnosing CAD was only 80%.

When coupled with exercise stress testing results, fewer false-positive results occurred, but accuracy did not improve, the investigators note.

"The relatively low cost for EBCT...screening (approximately $400), brief testing time (under 10 min), and no need for a physician during scanning makes it a reasonable alternative to traditional stress testing," the authors conclude.

The ACC/AHA Writing Group examined 16 studies from the medical literature, including nearly 4,000 patients, for evidence of EBCT's accuracy and usefulness in diagnosing CAD and in assessing the risk of heart disease in various patients.

Based on their review, the Group concludes, "The EBCT is not superior to other currently available diagnostic procedures for diagnosis of angiographic CHD (coronary heart disease)."

While admitting that EBCT might be useful in placing patients into CHD risk categories, the expert panel notes that "the published literature does not clearly define which asymptomatic people require or will benefit from EBCT."

"In the setting of this degree of uncertainty, EBCT screening should not be made available to the general public without a physician's request," states the consensus document.

Finally, the committee calls for additional studies to assess the proper role of EBCT in diagnosing or screening for the presence of CHD.

"We don't state that EBCT isn't useful," explained O'Rourke in a news release. "What we would like to see are additional properly designed studies to determine when the procedure is useful and when it's not."

Sources

Journal of the American College of Cardiology 2000;36:32-38, 326-350.


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