A Clinical Score to Predict Acute Kidney Injury After Heart Valve Replacement Surgery

Acute kidney injury (AKI) is a common and severe complication of cardiac surgery. The main stay treatment remains preventive with no clear evidence supporting any therapeutic interventions. AKI risk prediction scores are an objective, transparent means of cohort enrichment but are not widely used. The purpose of this analysis was to develop and validate a clinical score including pre-,intra-and post-operative predictors that predicted AKI following heart valve replacement surgery. This prediction score allows identification of patients at high risk of AKI and may support decision-making for protective kidney treatment.

This study is a single center retrospective observational study designed to to develop and validate a clinical score that predicts AKI after heart valve replacement surgery。 To achieve this goal, patient underwent heart valve replacement surgery will be screened for enrollment eligibility. For the purpose of this analysis, only the first surgical episode was considered. Patients required preoperative dialysis, with any degree of renal insufficiency (acute or chronic) and patients who had end-stage renal disease (estimated glomerular fltration rate \[eGFR\] \< 15 mL/min /1.73m2 )are not included in study.

AKI was classified according to the KDIGO definition\[10\]. Stage-1 AKI: increase in serum creatinine of more than or equal to 0.3 mg/dl (≥ 26.5μmol/l) or increase to more than or equal to 150% to 200% (1.5≤x\<2) from baseline within 7 days. Stage-2 AKI: Increase in serum creatinine to more than 200% to 300% (2≤x\<3) from baseline. Stage-3 AKI: Increase in serum creatinine to more than 300% (3≤) from baseline (or serum creatinine of more than or equal to 4.0 mg/dl (≥ 353.6μmol/l) or when the patient commenced RRT.

We selected demographic, preoperative, intra-operative and early postoperative variables considered predictors of AKI.

1. The demographic and preoperative factors included age, sex, weight, height; history of smoke, drink, angina, cerebrovascular disease, COPD, peripheral vascular disease, hypertension, valve infection , arrythmia , diabetes mellitus, MI , atrial fibrillation, pulmonary hypertension, previous cardiac surgery; NYHA stage, surgery type , Operative approach and emergency surgery。The latest value before operation: serum creatinine level, haemoglobin, capillary glucose, hemoglobin，WBC, EF, LDL-C , urinary protein, CRP, PCT, ALB, TBIL, PT and Glomerular filtration rate (GFR). History of taking the following drugs before surgery: contrast, nephrotoxic antibiotics, β-blocker, calcium channel blocker, lasix, ACEI, ARB, immunosuppressive, heparin, aspirin, clopidogrel, ticagrelor, digoxin, levosimendan, dopamine, dobutamine, cedilanid, isosorbide dinitrate, isosorbide mononitrate, isoprenaline and NASID.
2. The intra-operative factors included cardiopulmonary bypass time, cross-clamp time, transfusion, FFP, VFP, CFP，output and input ; the highest blood glucose, minimum hematocrit, minimum mean arterial pressure, minimum temperature and fluid balance during CPB.
3. The postoperative factors included time to extubation, mean ICU and hospital stay and mortality. First measured value after entering ICU: CVP, PH, HB.

We also considered postoperative complications during the intensive care unit included IABP, ECMO, cardiac arrest, arrhythmia, re-intubation, return to ICU，tracheotomy.

Eligibility Criteria:
Inclusion Criteria:

* \> 18 years
* Subjects undergoing heart valve replacement surgery

Exclusion Criteria:

* Pregnancy
* Transplant donor or recipient
* Required preoperative dialysis, with any degree of renal insufficiency (acute or chronic) and patients who had end-stage renal disease (estimated glomerular fltration rate \[eGFR\] \< 15 mL/min /1.73m2 )
* Local anesthesia
* Lack of creatinine