Biochemical response to aortic cross-clamp duration: CK-MB and Troponin-I dynamics during myocardial ischemia in CABG patients.

Objective: To evaluate perioperative changes in creatine kinase–myocardial band (CK-MB) and cardiac troponin-I levels in patients undergoing coronary artery bypass grafting (CABG) in relation to aortic cross-clamp duration. Study Design: Cohart Study. Setting: Department of Cardiac Surgery, Punjab Institute of Cardiology, Lahore, Pakistan. Period: Six Months from November 2022 to April 2023. Methods: A total of 190 patients undergoing elective on-pump CABG were included using a non-probability consecutive sampling. Patients were categorized into two groups based on aortic cross-clamp duration: Group A (<75 minutes) and Group B (≥75 minutes). Blood samples were collected at baseline, after cross-clamp removal and during the early postoperative period. Serum CK-MB and troponin-I levels were measured. Data was analyzed by SPSS version 25. Quantitative variables were expressed as mean ± standard deviation and an independent sample t-test was used to compare biomarker levels between the groups. A p-value ≤0.05 was considered statistically significant. Results: Baseline CK-MB and troponin-I levels were similar between two groups. Both biomarkers showed a significant increase after cross-clamp removal, reflecting myocardial stress associated with surgical ischemia. CK-MB levels increased significantly after cross-clamp exposure=0.004) and remained elevated in the early postoperative period (p=0.030). Similarly, troponin-I levels showed a significant rise following cross-clamp removal (p=0.035) and remained elevated postoperatively (p=0.050). Conclusion: Perioperative monitoring of CK-MB and troponin-I provides useful insight into myocardial injury during CABG and may help improve assessment of myocardial protection during cardiac surgery.