Background and objectives In critically ill patients, acute kidney injury (AKI) influences mortality and morbidity. Few studies have looked at mortality and the frequency of AKI following successful heart and thoracic operations. The current study investigates the association between AKI and mortality rates among patients undergoing post-cardiac surgery care within the Cardiology & Cardio Vascular Thoracic Surgery (CVTS) Intensive Care Unit (ICU). Methodology In this prospective research, 124 patients who underwent successful cardiovascular and thoracic procedures between June 2022 and June 2023 were admitted to the CVTS ICU. To determine mortality, we contrasted the two scoring methods, Kidney Disease-Improving Global Outcomes (KDIGO) and Risk, Injury, Failure, Loss of kidney function, and End-stage kidney disease (RIFLE). Results Based on the KDIGO criteria, AKI was identified in 37.90% (n = 47) of the patients, and it was identified in 15.32% (n = 19) of the patients utilizing RIFLE. Notably, patients diagnosed with AKI using either the RIFLE criteria or KDIGO criteria exhibited considerably higher mortality rates (p< 0.001). Receiver operating characteristic (ROC) analysis demonstrated the effectiveness of both scoring systems in identifying mortality (area under the ROC curve for RIFLE = 0.224 and KDIGO = 0.150). Conclusion Post-cardiac surgery, AKI escalates both mortality and morbidity rates. Despite KDIGO detecting more severe renal injury and mortality, both scoring systems exhibit comparable sensitivity and specificity in predicting death among patients undergoing various cardiovascular and thoracic procedures., Competing Interests: Human subjects: Consent was obtained or waived by all participants in this study. University Clinical Studies Ethics Committee and Medical Institute Ethical Committee, DIT University, Dehradun, India issued approval DITU/UREC/2022/04/3. Animal subjects: All authors have confirmed that this study did not involve animal subjects or tissue. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Jan et al.)