CE-MARC: CMR more sensitive than SPECT at detecting CAD in both sexes

Cardiovascular magnetic resonance was more sensitive at detecting CAD in both sexes than single-photon emission CT, according to new data from the CE-MARC study.

The diagnostic performance of cardiovascular magnetic resonance (CMR) did not differ between the sexes, whereas accuracy with SPECT was significantly worse in women than in men, John P. Greenwood, PhD, and colleagues found.

In the main results of CE-MARC, published in 2012, CMR was found to have more sensitivity and better negative predictive value for the identification of CAD than SPECT, but there were no differences in specificity or positive predictive value.

In the present substudy, the diagnostic accuracies of both technologies were assessed according to sex. “The overall aim was to increase the evidence base for appropriate noninvasive imaging test selection in women with suspected CAD,” Greenwood, of the University of Leeds, United Kingdom, and colleagues wrote. “… Additional analyses compared the perfusion-only components of CMR and SPECT and assessed the effects of factors thought to reduce their accuracy in women, namely small heart size, disease pattern and breast size.”

Greenwood and colleagues performed CMR and SPECT on 235 women and 393 men with suspected angina. All participants also underwent coronary angiography as a reference test, independent of the CMR or SPECT result, to avoid referral bias, according to the study background.

For CMR, sensitivity was similar between the sexes (women, 88.7%; men, 85.6%; P=.57), as was specificity (women, 83.5%; men, 82.8%; P=.86). For SPECT, sensitivity was worse in women than in men (50.9% vs. 70.8%; P=.007), but there was no difference in specificity (women, 84.1%; men, 81.3%; P=.48).

Sensitivity for both women and men was higher with CMR than with SPECT (P<.0001 for both), but there was no difference in terms of specificity (women, P=.77; men, P=1), the researchers found. For the perfusion-only components, CMR outperformed SPECT in women (area under the curve=0.9 compared with 0.67; P<.0001) and in men (area under the curve=0.89 vs. 0.74; P<.0001).

Greenwood and colleagues found that diagnostic accuracy was similar in both sexes for perfusion CMR (P=1), but worse among women for SPECT (P<.0001). The lower accuracy of SPECT in women appears to be related to smaller heart size, not breast attenuation, they wrote.

“These findings, plus an absence of ionizing radiation exposure, mean that CMR should be more widely adopted in women with suspected CAD,” Greenwood and colleagues wrote. “… The major challenge for SPECT in females appears to be the smaller heart size rather than breast attenuation artifacts. CMR may be less susceptible to these effects due to its inherent higher spatial-resolution, even in the setting of multi-vessel CAD.”

Disclosure: The researchers report no relevant financial disclosures.