Associations between preoperative continuation of renin-angiotensin system inhibitor and cardiac surgery-associated acute kidney injury: a propensity score-matching analysis.

Background: Cardiac surgery-associated acute kidney injury (CSA-AKI) is associated with high risk for complications and mortality. Whether renin-angiotensin system (RAS) inhibitor should be continued or withdrawn in patients with long-term use before cardiac surgery has been lack of consensus.

Methods: We performed this prospective observational cohort study and recruited cardiac surgery patients in the surgical intensive care units between 2000 and 2011. These patients were divided into users and non-users of RAS inhibitor. Propensity score matching and multivariable models were performed to investigate the association between renal outcome, mortality, and preoperative use of RAS inhibitor.

Results: Preoperative use of RAS inhibitor was identified as the independent protective factor for AKI development (OR 0.41, 95% CI 0.23, 0.63), AKI severity (stage 3 vs. stage 1, OR 0.35, 95% CI 0.18, 0.69), and renal recovery (OR 3.41, 95% CI 1.84, 5.36). Nevertheless, there was no significant protective effect of RAS inhibitor on in-hospital dialysis, in-hospital mortality, and ensuing development of chronic kidney disease (CKD) after AKI. We created a prediction model of CSA-AKI and indicated that preoperative use of RAS inhibitor provided more protective effect in low-risk than high-risk population.

Conclusion: Preoperative use of RAS inhibitor was associated with less AKI development and severity, and higher renal recovery. Although more risk reduction of AKI development was shown in low-risk group by our prediction model, continued use of RAS inhibitor before cardiac surgery could provide protective effect in all patients.