EF1 remains stable with age and correlates more strongly with LV contractility (Ees) than LVEF, especially in adults >55 years, making EF1 a superior LV function measure.
Does first-phase ejection fraction (EF1) provide a more stable and superior measure of LV contractility across the lifespan compared to LVEF in healthy adults?
First-phase ejection fraction (EF1) is less affected by age than LVEF and serves as a superior surrogate of LV contractile function, particularly in older adults.
Abstract Background First-phase ejection fraction (EF1), the ejection fraction (EF) up to peak aortic velocity (dQ/dt+), is a novel biomarker of left ventricular (LV) function, which can be measured non-invasively on echocardiography. At the onset of myocardial dysfunction, cardiomyocytes may preserve LVEF by compensating with slower, sustained contraction. EF1 is able to quantify this altered physiology and has been shown to outperform conventional measurements of LV function in the prediction of future systolic dysfunction and major adverse cardiac events 1. To the best of our knowledge, no studies have assessed EF1 in non-diseased individuals. Purpose To calculate reference values of EF1, investigate if it varies across the lifespan, and compare it with LVEF alongside the gold-standard measure of LV contractility, end-systolic elastance (Ees), in healthy individuals. Methods A synthetic dataset modelling haemodynamics and pulse waves 2, validated in vivo, was used in this analysis. LVEF was derived from aortic root pressure waveforms using a circulatory model validated in vivo 3. As the area under the aortic flow wave is proportional to stroke volume (SV), SV at dQ/dt+ (SV1) was derived as the area under the aortic flow wave up to dQ/dt+. EF1 was then calculated as SV1 / end-diastolic volume x 100 (Figure 1). Ees was calculated as aortic root end-systolic pressure / end-systolic volume. The effect of age on EF1 and LVEF was assessed using linear regression. Relationships between age, EF1, LVEF, and Ees were quantified using Spearman’s correlation coefficient. Summary statistics are presented as mean ± standard deviation. Results 3837 individuals spread evenly across the lifespan were included in this analysis (age: 48.6±17.0y, LVEF: 67.0±1.7%, EF1: 50.0±3.1%, Ees: 3.68±0.8). With ageing, EF1 remained virtually unchanged (25y: 49.6±3.26, 35y: 49.8±3.0, 45y: 49.9±3.0, 55y: 50.1± 3.1, 65y: 50.4 ±3.1, 75y: 50.4 ± 3.2) and was less related to age than LVEF (β: 0.16 95% Confidence Interval 0.10,0.22 vs β: -0.27 -0.30,-0.24, both per 10y increase, both p0.001) (Figure 2). LVEF was moderately correlated with EF1 (ρ: 0.46) and there was a significant interaction with age (p0.001). The correlation between LVEF and EF1 decreased with ageing, especially in individuals 55y (25y: 0.69, 35y: 0.55, 45y: 0.49, 55y: 0.45, 65y: 0.36, 75y: 0.32 all ρ). EF1 had a stronger correlation with Ees than LVEF, notably in older adults (25y: 0.77 vs 0.62, 35y: 0.77 vs 0.54, 45y: 0.74 vs 0.51, 55y: 0.73 vs 0.42, 65y: 0.70 vs 0.28, 75y: 0.65 vs 0.13 all ρ) demonstrating it to be a superior measure of LV contractility. Conclusion For the first time, we have described standard reference values for EF1 - which can be used to inform abnormality thresholds - and the evolution of EF1 across the lifespan. We have also shown EF1 is less affected by age than LVEF and serves as a superior surrogate of LV contractile function, particularly in older adults.Figure 1 Figure 2
Long et al. (2025) studied this question. EF1 remains stable with age and correlates more strongly with LV contractility (Ees) than LVEF, especially in adults >55 years, making EF1 a superior LV function measure.