Abstract
BackgroundAccurate prediction, early detection and treatment of acute kidney injury (AKI) are essential for improving post-operative outcomes. This study aimed to examine the role of aortic stiffness and neutrophil gelatinase-associated lipocalin (NGAL) as predictors of AKI or need for early medical renal intervention following aortic valve replacement (AVR).MethodsAortic pulse wave velocity and plasma NGAL were measured pre-operatively in recruited patients undergoing AVR for aortic stenosis (AS). Plasma NGAL was also measured at 3 and 18–24 hours after cardiopulmonary bypass (CPB). AKI was defined using RIFLE criteria. Early medical renal intervention included diuretics or dopamine infusion exclusively for renal causes.ResultsFifty-three patients aged 71 ± 9 years were included. Sixteen (30%) developed AKI (AKI-Yes) and 24 patients (45%) received early medical intervention (Intervention-Yes). There was no significant difference in the demographic, clinical or operative characteristics between the two groups for either outcome. PWV did not significantly correlate with AKI (r = 0.12, P = 0.13) or early intervention (r = 0.18, P = 0.18). At 3 h post-CPB, plasma NGAL was a much stronger predictor of both AKI and the need for early medical intervention than conventional markers such as creatinine (AKI: AUC 83%, 95% CI 0.70–0.95 vs. AUC 65%, 95% CI 0.47- 0.82; Medical intervention: AUC 84%, 95% CI 0.72–0.96 vs. AUC 56%, 95% CI 0.38–0.73). Post-CPB (3 hr) plasma NGAL was also significantly associated with AKI (r = 0.68, P < 0.001) at levels above 150 ng/ml; and significantly associated with early intervention (r = 0.64, P < 0.001) above 136 ng/ml. Simple linear regression showed no relationship between PWV and NGAL levels.ConclusionAortic PWV does not correlate significantly with post-operative AKI or plasma NGAL levels in surgical AS patients. Post-operative NGAL is however an early and powerful predictive biomarker of both post-operative AKI and the need for early medical renal intervention and should consequently be considered in prediction models for AKI after cardiac surgery.
Highlights
Accurate prediction, early detection and treatment of acute kidney injury (AKI) are essential for improving post-operative outcomes
The objectives of this study are 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 neutrophil gelatinase-associated lipocalin (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
Acute kidney injury, and early medical renal intervention There was no significant difference in pulse wave velocity (PWV) (m/s) between AKI-No and AKI-Yes groups or between Intervention-No and Intervention-Yes groups (Table 2)
Summary
Early detection and treatment of acute kidney injury (AKI) are essential for improving post-operative outcomes. Post-cardiac surgery acute kidney injury (AKI) is associated with significant morbidity and mortality [1,2], and may occur in up to 30% of adult patients [3,4], with between 1% and 5% requiring renal replacement therapy [5,6,7]. Several large clinical studies have been used to develop risk stratification models to achieve better AKI prediction, prevention and management [3], and a long list of predictors/risk factors have been identified [3,9]. There is limited evidence to link aortic stiffness with renal function in non-kidney disease patients [12,13,14], and its role after cardiac surgery is yet to be investigated. Preliminary data does suggest that elevated arterial stiffness may be an early predictor of renal function decline in the general population [12,13]
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