Sex differences in the agreement between left ventricular ejection fraction measured by myocardial perfusion...

Left ventricular ejection fraction (LVEF) is generally measured by echocardiography but is increasingly available with myocardial perfusion scintigraphy. With myocardial perfusion scintigraphy, 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 echocardiography and myocardial perfusion scintigraphy.

Four hundred and four men, mean age = 67.7 ± SD = 12.3 yr; 339 women, 67.7 ± 11.7 yr had separate myocardial perfusion scintigraphy and echocardiography examinations within six months. A subset of 327 of these patients (181 men, 68.8 ± 12.1 yr; 146 women, 66.4 ± 12.1 yr) had examinations within one month and were additionally analysed as this sub-group. Myocardial perfusion scintigraphy and echocardiography were used to measure LVEF at rest and their agreement (neither considered as a reference method) was assessed by Bland-Altman plots: LVEF difference (myocardial perfusion scintigraphy minus echocardiography ) against average LVEF ( $$ ).

Of patients who had myocardial perfusion scintigraphy and echocardiography performed within six months, 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.

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.