Myocardial Perfusion Imaging Urged As Initial Prognostic Test in Women

ORLANDO — Myocardial perfusion imaging substantially restratifies women who have a moderate or high Duke Treadmill Score on exercise stress testing, with resultant markedly improved identification of those at elevated risk of a cardiovascular event as well as those who are not, Justin B. Lundbye, M.D., said at the annual meeting of the American College of Cardiology.

“Exercise myocardial perfusion imaging provides considerable incremental prognostic information over exercise stress testing alone. In this subset of women with intermediate to high pretest likelihood of coronary artery disease [CAD] based on Duke Treadmill Score, we feel that consideration should be given to utilization of exercise myocardial perfusion imaging as the first-line test,” asserted Dr. Lundbye of Hartford (Conn.) Hospital.

Such a proposal is at odds with current ACC/American Heart Association guidelines, which recommend exercise stress testing (EST) alone as the preferred modality in women with an intermediate or high pretest probability of CAD. But those guidelines are due for an overhaul, Dr. Lundbye argued, adding that because of the nature of EST, many women will have false-positive results. And that leads to numerous unnecessary coronary angiograms. Perfusion imaging reliably subclassifies women into two groups: those who require further testing and those who do not.

He reported on 1,020 women with an intermediate or high pretest likelihood of significant CAD who underwent EST along with technetium-99 sestamibi myocardial perfusion imaging. During a mean 2.4 years of follow-up, women with a moderate Duke Treadmill Score in the range of −10 to +4 (high risk to moderate risk) had an overall 3% annual rate of all-cause mortality, nonfatal MI, or coronary revascularization performed more than 2 months after their EST. Among the subset who had an abnormal myocardial perfusion imaging study, the combined annual event rate was 17%. In those with a normal perfusion imaging study, it was 2%.

Similarly, among women with a high-risk Duke Treadmill Score of -11 or less, the overall annual event rate was 12%. In those with an abnormal perfusion scan, the annual event rate climbed to 28%, while in those with a negative scan the rate was 4%.