Acute kidney injury as a risk factor for heart failure hospitalisation after major non-cardiac surgery

Abstract Aim The importance of acute kidney injury (AKI) after major non-cardiac surgery is incompletely understood. The aim of this study was to evaluate the association of AKI with short-term complications (e.g. perioperative myocardial injury (PMI); acute heart failure (AHF)), and long-term adverse outcomes (e.g. readmission for AHF, all-cause mortality). Methods The prospective observational international multi-center BASEL PMI study screened inpatients aged 40-85 at high cardiovascular risk undergoing non-cardiac surgery at tertiary hospitals to detect asymptomatic PMI. This secondary analysis focused on AKI, with prospective adjudication of AKI, PMI and AHF by blinded experts. Results In 11'133 patient cases, the incidence of AKI within 7 days was 11.1%, classified as KDIGO stage one (68.3%), two (15.4%) and three (16.3%). Pre- and perioperative determinants for AKI were perioperative myocardial infarction / injury (PMI, OR 3.63), the need for intra-operative blood transfusion (OR 1.48), chronic heart failure (CHF, OR 1.42), surgery duration (OR 1.37), male sex (OR 1.27), preoperative GFR (OR 0.80) and preoperative hemoglobin concentration (OD 0.84). Median time to occurrence of AKI was 2 days (IQR 1-4), similar to PMI (median 1, IQR 1-2) and in contrast to AHF (median 4, IQR 2-9). 41% of all AKI patients experienced additionally a PMI. In multivariable Cox regression analysis, AKI (aHR 1.76, 95% CI 1.51-2.06, p < 0.001) and PMI (aHR 1.21, 95% CI 1.02-1.45, p = 0.025) were both independently associated with prediction of one-year all-cause mortality after adjustment for each other and confounding factors, whereas AHF was marginally not (aHR 1.28, 95% CI 0.98-1.68, p = 0.070). However, testing the assumed proportional hazards assumption, the impact of AKI, PMI and AHF on mortality depended significantly on time. AKI had significantly increased short- and long-term mortality, in contrast to PMI and AHF with just elevated short-term mortality. The coincidence of AKI and PMI resulted in an additive effect on overall mortality. Importantly, patients with AKI showed more in-hospital AHF (aHR 2.08, 95% CI 1.49-2.91) within 30 days and higher hospitalization rates for HF within one year (aHR 1.40, 95% CI 1.01-1.98, p = 0.046) than patients without AKI, particularly patients without known heart failure (aHR 1.65, 95% CI 1.05-2.60, p = 0.029). Conclusion AKI is a common complication, occurring in 11% after non-cardiac surgery. The occurrence of AKI was associated with increased risks for in-hospital AHF, hospitalizations for heart failure and all-cause mortality. Notably, AKI patients without known history of heart failure faced hospitalizations for de novo heart failure. The occurrence of AKI unveiling de novo heart failure highlights the importance of systematic monitoring for AKI after surgery and gives clinicians a window of opportunity to take action at an early stage.