Objectives: This study sought to determine the rate of referral to cardiac catheterization in men and women early after nuclear testing as a function of the magnitude of myocardial ischemia by radionuclide perfusion imaging.
Background: Although many previous studies have suggested that gender-related differences are present in the clinical management of coronary artery disease, the presence of such a difference with respect to referral to catheterization after noninvasive testing is disputed.
Methods: We examined 3,211 consecutive patients (1,074 women, 2,137 men) who underwent exercise dual-isotope single-photon emission computed tomography and had follow-up evaluation performed at least 1 year after nuclear testing (mean [+/- SD] follow-up 19 +/- 5 months) for "hard" events (cardiac death and myocardial infarction) and referral to cardiac catheterization or revascularization within 60 days of nuclear testing. Multiple logistic regression analysis was performed to determine the best predictors of referral to catheterization as well as to examine whether gender itself added further information to this model.
Results: Although men were referred to catheterization more frequently than women (10.6% vs 7.1%, p < 0.001) early after exercise nuclear testing, there were no differences in the rate of referral to catheterization or revascularization after stratification by the amount of abnormally perfused myocardium detected by the nuclear scan. Both men and women with normal scan results were infrequently referred to subsequent catheterization. In the setting of severe ischemia, women were referred to catheterization more frequently than men. This higher rate appears to be clinically appropriate because women with severely abnormal scan results had a significantly higher event rate than men (17.5% vs. 6.3%, p < 0.0001). This greater risk in women than in men appeared to be underappreciated because the increased rate of hard events in women with severely abnormal scan results was out of proportion to the smaller increase in their rate of referral to cardiac catheterization. Although gender added information to the multivariate model most predictive of referral to catheterization models when nuclear variables were not included, when nuclear variables were considered, the addition of gender added no further significant information. This finding suggests that adjusting for differences in perfusion scan abnormalities by the use of nuclear testing eliminated the apparent gender-related referral bias.
Conclusions: After controlling for differences in perfusion scan abnormalities, no gender-related referral bias to catheterization was present. In the setting of severe ischemia, women had a greater rate referral to catheterization than men. As a function of risk, both men and women were appropriately referred to catheterization at a low rate when the scan result was normal. However, because women with severe perfusion abnormalities had a greater rate of cardiac death and myocardial infarction then men, women in this high risk subgroup were underreferred to catheterization relative to men. This finding points to the need to better identify women at high cardiac risk.