Coronary CT angiography (CCTA) has been shown to have comparable diagnostic accuracy for both women and men for the detection of obstructive coronary stenosis. The higher specificity for women as compared to traditional tests could lead to lower rates of unnecessary invasive tests, according to a study published in the July issue of the Journal of Cardiovascular Computed Tomography.

The study was a subgroup analysis of data from the ACCURACY (Assessment by Coronary Computed Tomographic Angiography of Individual Undergoing Invasive Coronary Angiography) trial, which is the first prospective multicenter trial for CCTA efficacy in patients without known coronary artery disease (CAD) or with intermediate prevalence of CAD, according to the study’s authors.

“Traditional tests have suboptimal performance in female patients compared with male patients,” wrote Janet C. Tsang, MD, of the Los Angeles Biomedical Research Institute at Harbor-University of California, Los Angeles Medical Center, and colleagues. “Exercise electrocardiography has found lower sensitivities and specificities (61 percent and 70 percent, respectively, for women, in comparison with 80 percent for both sensitivity and specificity in men).” Stress myocardial perfusion imaging has similar limitations, noted the authors.

To compare the diagnostic accuracy of CCTA between men and women without known CAD, Tsang and colleagues prospectively evaluated 230 subjects—136 men and 94 women with a mean age of 57—experiencing chest pain at 16 sites who were clinically referred for invasive coronary angiography (ICA). ICA results were used as the reference standard in evaluating the CCTA test.

Results showed that for a patient-based model for stenosis at the 50 percent threshold, CCTA had a sensitivity and specificity of 96 percent and 78 percent, respectively, in men, and 90 percent and 88 percent, respectively, in women. Negative predictive values (NPVs) were 100 percent in men and 99 percent in women.

“No significant differences were observed in diagnostic characteristics in comparison between men and women at the 50 percent threshold, and only improved specificity in women was noted at the 70 percent threshold, with no significant differences in NPV or [positive predictive value],” wrote Tsang and colleagues.

The authors stressed the role CCTA could play in limiting the sizeable proportion of women who are referred unnecessarily for ICA.

“Perhaps most importantly, the >99 percent NPVs seen in both sexes greatly supports the use of coronary CTA as an effective noninvasive test for accurately ruling out obstructive CAD. Because >50 percent of symptomatic, low-to-intermediate risk female patients referred for invasive evaluation show no evidence of obstructive CAD on coronary angiography, coronary CTA may be a particularly useful noninvasive test for improving the rate of normalcy with invasive angiography among women.”