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The presence of coronary artery calcium (CAC) can help select which patients with chest pain should undergo myocardial perfusion PET, according to Atlanta-based researchers.

The presence of coronary artery calcium (CAC) can help select which patients with chest pain should undergo myocardial perfusion PET, according to Atlanta-based researchers.

"The importance of our work," senior investigator Dr. Paolo Raggi told Reuters Health, "resides in the fact that the use of hybrid imaging systems, such as the combined PET/CT described in our study, allows us to quickly identify patients who will not require any nuclear testing in the absence of coronary calcium -- a well known marker of atherosclerosis."

In the January 15th issue of the American Journal of Cardiology, Dr. Raggi and colleagues at Emory University School of Medicine note that at their institution, patients presenting with chest pain are often referred for adenosine stress rubidium-82 (Rb-82) myocardial PET.

To investigate whether CAC might help predict the outcome of such testing, the researchers studied 84 patients with a low-to-intermediate likelihood of coronary artery disease.

All underwent non-contrast CT to assess CAC followed by adenosine stress Rb-82 myocardial perfusion PET.

The 34 patients without CAC also had normal PET results, for a negative predictive value of 100 per cent.

CAC was observed in the remaining 50 patients, and 13 of these patients had myocardial perfusion defects, giving a positive predictive value of 26 per cent. The sensitivity was 100 per cent and the specificity was 48 per cent.

Using this approach, the investigators conclude that "myocardial perfusion PET imaging could have been obviated in 63 per cent (31 of 49) of patients with no smoking history and no prior myocardial infarction or coronary revascularization procedure, and in 37 per cent (31 of 84) of the total."

Should the findings be confirmed, the team concludes, use of noncontrast CT "may decrease overall radiation exposure and hospital time and prove to be cost effective."

"In view of the ever-climbing cost of medical care, any approach that may reduce the performance of potentially unnecessary testing should be welcome," Dr. Raggi added.