Background: Acute kidney injury (AKI) is a frequent complication of open-heart surgery, with a reported global incidence of 20-40%. Local Iraqi data on postoperative AKI incidence and predictors remain limited despite its designation as a 2025 Iraqi Ministry of Health perioperative research priority.

Objectives: To determine the incidence, severity, independent predictors, and short-term outcomes of AKI among adult patients undergoing open-heart surgery at a tertiary cardiac center in Iraq.

Methods: This single-center observational case-series analyzed 99 adults undergoing elective open-heart surgery at the Iraq Center for Heart Diseases, Baghdad, between January 2024 and December 2025. Patients with end-stage renal disease on dialysis or chronic kidney disease stage 4 were excluded. Preoperative renal dysfunction was defined as serum creatinine >1.1 mg/dL or estimated glomerular filtration rate <60 mL/min/1.73 m2. AKI was diagnosed and staged using KDIGO serum-creatinine criteria. Statistical analysis included Mann-Whitney U, chi-square/Fisher exact tests, and multivariable logistic regression.

Results: AKI occurred in 23/99 patients (23.2%): 19 (82.6%) were KDIGO stage 1, two (8.7%) stage 2, and two (8.7%) stage 3. One AKI patient (4.3%) required new postoperative renal-replacement therapy. In the adjusted model, male sex (adjusted OR 8.43, 95% CI 1.50-47.46, p=0.016) and impaired baseline renal function (adjusted OR 7.11, 95% CI 1.58-32.05, p=0.011) were independent predictors. CPB duration >120 minutes showed a numerically higher AKI incidence but was not statistically significant.

Conclusion: Postoperative AKI occurred in nearly one quarter of patients. Male sex and impaired baseline renal function were the only independent predictors, supporting targeted preoperative renal-risk stratification and postoperative renal surveillance in Iraqi cardiac centers.