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

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 1min 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).ConclusionExercise 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