Fewer women than men have positive SPECT and PET cardiac findings among patients with no history of heart disease

A lower detection rate of coronary artery disease (CAD) has been reported for SPECT imaging in women, despite the fact that similar numbers of women and men die each year of heart disease. Ruling out instrumentation as a possible source of this low detection rate for CAD in women could be important in determining the root cause of this difference. Methods: Patients were referred by cardiologists and randomized to PET or SPECT by the imaging center. A total of 210 patients (106 women, 104 men) were enrolled in this study, with 105 imaged by dual-isotope SPECT and 105 imaged by ⁸²Rb PET. Rest/stress scanning was performed using dipyridamole. The effects of sex, prior history of CAD, and instrumentation on the detection of positive scans were determined using multiple logistic regression analysis with positive scans as the endpoint. Results: For the total study population, sex and prior history of CAD are significantly associated with positive scans, whereas imaging modality and age are not. There was no significant interaction between sex and prior history of CAD. Men have 4.1-fold greater odds of having a positive nuclear scan than women, and patients with prior history of CAD have 5.2-fold greater odds of a positive scan after controlling for the confounding effects of age and imaging modality. In the subgroup of patients with no prior history of heart disease, men have 3.9-fold greater odds of a positive scan than women, and the odds ratio of a positive scan is 2.5-fold greater for PET than for SPECT. There was no statistical difference in the number of positive scans by SPECT or PET, or positive scans by sex in patients with documented history of CAD. Conclusion: Fewer women than men have positive nuclear cardiology scans by both PET and SPECT, despite similar symptoms. Instrumentation characteristics alone do not account for this sex- based difference and suggest the possibility that early CAD may present differently in women than in men.