Left ventricular ejection fraction (EF) is a major determinant of survival in patients with coronary artery disease (CAD). Comparative accuracy of numerous modalities in calculating EF is not well investigated.
We compared EF as calculated by rest and post-stress Cedars automated quantitative gated SPECT (AQGS), rest and post-stress semi-automatically processed gated SPECT (MQGS), echocardiography and contrast ventriculography (LVG) to those determined by rest and post-stress cavity-to-myocardium ratio (CMR) in 109 patients. Gated SPECT was performed based on a 2-day protocol using Tc-MIBI.
Mean EF in LVG, echo, post-stress CMR, rest CMR, post-stress AQGS, rest AQGS, post-stress MQGS and rest MQGS were 41.8%+/-12.1, 44.8%+/-11.8, 38.1%+/-10.7, 35.7%+/-12.1, 44.5%+/-15.1, 46.9%+/-14.7, 40.1%+/-14.3 and 43.5%+/-14.3 respectively. Although significant differences were observed between some of these methods, good and excellent linear correlations were present among values (all Pearson correlations >0.63). Considering LVG as the 'gold standard', we defined two groups: EF <35% (class 1) and >35% (class 2). Discriminant analysis showed that SPECT has the ability to predict patients' classes. In 4/18 of patients with normal SPECT (on both visual and quantitative analyses, SSS <4), EF on QGS showed a significant decrease on post-stress compared with rest.
There is a good correlation in calculating EF by LVG, QGS and echocardiography, regardless of EF value. Whenever QGS is impossible, CMR is a reliable indirect indicator of EF. Gating of both phases (and when impossible, CMR of both phases) has an additional value in d