Sex differences in the agreement between left ventricular ejection fraction measured by myocardial perfusion scintigraphy and by echocardiography

Background: Left ventricular ejection fraction (LVEF) is generally measured by echocardiography (Echo) but is increasingly available with myocardial perfusion scintigraphy (MPS). With MPS the threshold of LVEF below which there is a risk for myocardial infarct or sudden cardiac death is higher for women (51%) than for men (43%). We tested the hypothesis that such a sex difference may also occur with Echo and MPS. Methods: 404 men, mean age=67.7±SD=12.3yr; 339 women, 67.7±11.7yr had separate MPS and Echo examinations within 6months. A subset of 327 of these patients (181 men, 68.8±12.1yr; 146 women, 66.4±12.1yr) had examinations within 1month and were additionally analysed as this sub-group. MPS and Echo were used to measure LVEF at rest and their agreement (neither considered as a reference method) was assessed by Bland-Altman plots: LVEF difference (MPS minus Echo) against average LVEF (푀푀푀푀푀푀+퐸퐸퐸퐸ℎ표표2). Results: Of patients who had MPS and Echo performed within 6months, mean LVEF difference=+1.1% (95% limits of agreement: -19.3 to +21.6) in men but +10.9% (-10.7 to +32.5) in women. LVEF difference diverged from zero marginally in men (mean difference=+1.1, 95%CI =+0.1 to +2.1, p=0.028) but more in women (+10.9, +9.8 to +12.1, p<0.001). The LVEF difference correlated with average LVEF itself in both men (r=0.305, p<0.001) and women (r=0.361, p<0.001), and with age in women (r=0.117, p=0.031). Similar results were observed for the subset. Conclusions: Caution should be taken when interpreting LVEF measured by different techniques due to their wide limits of agreement and systematic bias, more markedly in women.