LCN2 and acute kidney injury: The objectives of this study are therefore to assess: (a) if aortic stiffness (measured by pulse wave velocity (PWV)) is a predictor of post- aortic valve replacement (AVR) AKI or the need for early medical renal intervention; (b) if NGAL may be a predictor of post-AVR AKI or predict the need for early medical renal intervention; and (c) if PWV is related to NGAL.