Cardiac surgery–associated acute kidney injury (CSA-AKI) is a frequent complication of coronary artery bypass grafting (CABG), yet contemporary data from Southeast Asia are sparse and established preoperative risk scores remain unvalidated in this region.

The KARMA Study was a 5-year retrospective cohort study of adults undergoing CABG at a tertiary Malaysian centre (January 2021–December 2025). CSA-AKI was defined and staged using KDIGO 2012 criteria. Multivariable logistic regression identified independent predictors of AKI, severe AKI, and in-hospital mortality. Four preoperative risk scores (Mehta, Cleveland Clinic, Simplified Renal Index, and Leicester) were evaluated for predicting severe AKI and CRRT requirement using ROC analysis. A descriptive subgroup analysis examined outcomes by CRRT initiation timing (≤24 h vs >24 h from AKI diagnosis); this analysis was substantially underpowered (n=24) and is hypothesis-generating only.

Among 551 CABG patients (mean age 62.3 years, 82.4% male), CSA-AKI occurred in 185 (33.6%): stage 1 in 70.3%, stage 2 in 13.5%, and stage 3 in 16.2%. In-hospital mortality rose from 3.8% (stage 1) to 40.0% (stage 3), with ICU stay, hospital stay, and renal recovery worsening at each advancing stage (p<0.001 for all). Independent predictors of any AKI included lower haemoglobin, higher baseline creatinine, emergency surgery, older age, and longer CPB time; predictors of severe AKI were lower haemoglobin and emergency surgery. Higher SOFA score and lower haemoglobin predicted in-hospital mortality. All four risk scores showed moderate discrimination (AUC 0.707–0.763 for CRRT; 0.720–0.748 for severe AKI) with high negative predictive values (>97.9%) but poor positive predictive values (7.2–16.4%). No significant difference in mortality or renal recovery was observed between early and late CRRT initiation groups.

CSA-AKI affected one-third of this multi-ethnic Malaysian CABG cohort and conferred markedly worse outcomes with increasing severity. Perioperative anaemia and prolonged CPB time were the most consistent modifiable risk factors. All four preoperative risk scores demonstrated comparable moderate discrimination, with high negative predictive values supporting their utility in ruling out patients unlikely to require dialysis. These results provide the first systematic characterisation of CSA-AKI risk prediction in a Southeast Asian CABG population.