Bing R, Gu H, Chin C, et al. - Researchers explored determinants of first-phase ejection fraction (EF1) as well as its prognostic worth in aortic stenosis. Among members of an echocardiography/cardiovascular magnetic resonance cohort investigation including patients suffering from aortic stenosis (peak aortic velocity of ≥2 m/s), EF1 was determined retrospectively. A follow-up of 238,029 person-days was performed in 149 participants. More severe aortic stenosis and more myocardial fibrosis (indexed extracellular volume (iECV) were observed in patients with low EF1. The identified independent predictors of EF1 were Zva (valvuloarterial impedance), iECV and infarct late gadolinium enhancement. Low baseline EF1 was identified as an independent predictor of aortic valve replacement (AVR)/death, driven by AVR. Overall, findings revealed that the quantification of early, potentially reversible systolic dysfunction in aortic stenosis was enabled by EF1. A link of EF1 with global afterload and myocardial fibrosis was also identified, and EF1 was shown to be an independent predictor of AVR.