ASNC: Non-invasive imaging? Where do WOMEN stand?

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DENVER—Myocardial perfusion SPECT should be limited to women with indeterminate or abnormal test results, Leslee J. Shaw, PhD, co-director of the clinical cardiovascular research institute at the Emory University School of Medicine in Atlanta, said during a presentation Sept. 11 at the 16th annual American Society of Nuclear Cardiology (ASNC) scientific session. However, as Shaw reported the results of the WOMEN trial, she concluded that in the future, more of an emphasis should be placed on guiding and evaluating patients via the accepted best practice.

“There is an abundance of evidence showing a higher diagnostic accuracy with myocardial perfusion imaging [MPI] over ECG-alone,” Shaw offered.

During the presentation, Shaw aimed to outline the implications of the WOMEN (What is the Optimal Method for Ischemia Evaluation in WomeN?) trial, which enrolled 824 women at an intermediate or high-risk for ischemic heart disease. Patients were randomized to receive either exercise ECG or an exercise test with nuclear imaging.

Shaw highlighted several challenges within WOMEN, including the fact that despite the fact that those enrolled were at an intermediate or high-risk of ischemic heart disease, the women were still functionally capable. “When you start to think about this patient population, you can see that about half the population was able to exercise for seven minutes or more,” she said. Therefore, one should assume that this is a lower-risk population who is functionally capable. “In fact, the vast majority were able to achieve maximum heart rate.”

Shaw called this a unique population of patients and also noted that during the study, women with more frequent chest pain had a higher likelihood of abnormal study results. “Abnormal results got worse with frequent angina symptoms,” Shaw said.

“As you start to query your female population there is a large population that is confusing. These are the patients who are able to perform activities and be active, but still have a large symptom burden.”

During the study, 412 patients were randomized to receive an exercise tolerance test (ETT) and 412 were randomized to receive exercise MPI. Shaw reported that the frequency of a normal study was high and frequency of abnormal scans was low; however, a quarter of the women had some abnormalities on the ECG.

Shaw said that major adverse cardiac event (MACE) free survival will be important for the future of comparative effectiveness research. However, during the WOMEN trial, Shaw said there were no differences in MACE free survival between the two groups.

As far as MACE rates go, when comparing ETT with exercise MPI, MACE rates were 0.4 percent vs. 1.2 percent respectively for patients with normal test results. As for patients with abnormal test results, these numbers were 5.1 percent vs. 13.1 percent.

“This trial will not be our panacea,” Shaw offered. “There is more driving management decisions rather than just outcomes.”

Shaw said that there is a “poor discriminatory ability of female cardiac symptoms to foster identification of at-risk women.”

During the study there was a low rate of follow-up angiography, 6 percent.

Shaw also discussed how WOMEN results will impact the future of comparative effectiveness research (CER). “If we are going to have a comparative research strategy, we must first address therapeutic intervention.” Previous CER trials have shown that included trials must reflect guideline-accepted best practices.

As far as the future of clinical trials, Shaw said, “We simply can’t randomize patients and then let them go. We have to guide them and evaluate them on the guideline-accepted best practices otherwise we are going to see even more negative trials.”

Shaw concluded that low-risk women should undergo exercise ECG first. Additionally, she said that follow-up MPI SPECT should be limited to women with indeterminate or abnormal test findings or those with persistent symptoms suggestive of coronary artery disease.

“This method may however be reasonable for patients with persistent symptoms where you are still worried about coronary disease.”