BOSTON— Contrast stress echocardiography is significantly more specific and no less sensitive than nuclear stress testing for evaluating chest pain in women who have a low to medium probability of coronary disease, a study has shown.
The findings suggest the ultrasound technique should be the preferred diagnostic test in this population, particularly because nuclear stress testing in women is complicated by a higher false positive rate than in men, Kenneth Ford, M.D., reported in a poster presentation at the annual meeting of the American Society of Echocardiography.
In comparing the accuracy of the two imaging modalities, Dr. Ford and his colleagues at Western Baptist Hospital in Paducah, Ky., enrolled 250 women with chest pain who were considered to be at low to intermediate risk for coronary artery disease (CAD). Women's average age was 53 years, and the average follow-up time was 543 days. Coronary disease risk-prediction factors included hypertension, diabetes, smoking, vascular disease, and family history.
Each woman underwent gated single-photon emission computed tomography (SPECT) with attenuation correction and contrast echocardiography, both at rest and immediately after a standard treadmill test, and each was injected with a weight-adjusted dose of sestamibi at peak stress followed by a 0.5-cc bolus of echo contrast. A single radiologist who was blinded to the stress echo results read all of the nuclear images.
“Patients with a reversible nuclear perfusion defect or a stress-induced wall motion abnormality on echocardiogram were urged to undergo a cardiac catheterization,” Dr. Ford noted.
Of the 250 women, 16 had significant CAD defined as more than 60% stenosis in the “culprit” vessel prompting major cardiac events during the study follow-up period, said Dr. Ford.
Major cardiac events included the need for percutaneous coronary intervention (PCI) or coronary artery bypass graft surgery (CABG), myocardial infarction (MI), and death. Of the 16 patients with significant disease, 13 underwent PCI, 2 required CABG, and 1 suffered MI.
The sestamibi test correctly identified 8 of the 16 true positive conditions; the ultrasound test correctly identified 12 of them. Because of the small numbers, the difference in the sensitivity rates was not statistically significant, said Dr. Ford.
The difference between the specificity achieved by each of the diagnostic imaging techniques was significant, Dr. Ford said. Among the 234 women without significant coronary disease, the sestamibi tests produced 15 false positives, for a specificity of 94%, compared with 2 false positives—specificity of 99%—from the ultrasound images.
The lower false positive rate of stress echo tests results in fewer unnecessary heart catheterizations in younger women with intermediate to low risk for heart disease, Dr. Ford noted.