1010-61 Influence of Gender on the Diagnosis of Coronary Artery Disease Using Exercise Thallium-201 SPECT

Abstract

Previous studies of TI-201 SPECT for the diagnosis of coronary artery disease (CAD) have not examined the influence of gender on the accuracy of the test. We examined the results of TI-201 in 567 pts (403 men, 164 women) who underwent exercise TI-201 SPECT and coronary angiography. All pts exercised maximally, with TI-201 injection 1 min prior to the completion of exercise. SPECT was obtained using a 2- or 3-headed camera, obtaining images within 10 minutes of stress and 4 h later. Using a 24 segment model, perfusion defects were identified by the reduction of regional activity >20% below maximal (>30% in inferior and posterior segments); reversibility was identified by > 15% increase of counts in the redistribution image. Two-dimensional echocardiograms were available in 163 pts (including 83 women), with measurements of left ventricular (LV) dimensions and calculation of LV mass using the Penn convention. Significant CAD (n = 324) was defined by stenoses >50% in the left main, >70% in the main coronary vessels; 172 had multivessel (MVD) and 152 had single vessel disease (SVD), with more SVD in women (55% vs 44%, P = NS). The overall sensitivity of exercise TI-201 SPEGT was 74%. The specificity in the 243 pts without CAD was 50% (41% in men, 67% in women), reflecting referral bias to angiography. Among 244 men with CAD, the sensitivity was 79%, compared with 61% in 80 women (p < 0.002). The sensitivity for MVD was 86% in men and women (p = NS). SVD was present in 108 men and 44 women, among whom the sensitivities were 83% and 59% respectively (p < 0.0001). In order to further evaluate the causes of lower exercise TI-201 sensitivity in women, a subgroup of 83 with echocardiographic data were analyzed. Pts with true positive (n = 26) and false negative (n = 18) results demonstrated a similar hemodynamic response to stress, workload, and LV dimensions. Pts with false negative findings had a higher prevalence of single vessel disease (89% vs 23%, P < 0.0001), and technically difficult studies (39% vs 4%, P = 0.01). Exercise TI-201 SPECT is effective for the diagnosis of MVD in women, but is less sensitive for the detection of SVD than in men. The lower sensitivity of TI-201 in women does not appear to be explained on the basis of LV dimensions or exercise capacity.