COMPARISON OF POSTOPERATIVE CARDIAC ENZYME LEVELS IN ON-PUMP VERSUS OFF-PUMP CORONARY ARTERY BYPASS GRAFTING

Abstract

Background: Coronary artery bypass grafting (CABG) remains a fundamental procedure for myocardial revascularization in patients with coronary artery disease. The two principal surgical approaches, on-pump CABG (ONCAB), which utilizes cardiopulmonary bypass, and off-pump CABG (OPCAB), performed on a beating heart, differ markedly in their physiological effects on myocardial tissue. Postoperative cardiac biomarkers, including CK-MB, Troponin I, and Troponin T, serve as sensitive indicators of perioperative myocardial injury. Objective: To compare postoperative cardiac enzyme levels between ONCAB and OPCAB procedures and determine the relative extent of myocardial injury associated with each technique. Study Design:  Non-randomized controlled trial. Settings: Department of Cardiothoracic Surgery, Punjab Institute of Cardiology, Lahore, Pakistan. Duration of Study: 11 April to 11 July 2025. Methods: Sixty-eight patients undergoing elective CABG were enrolled using non-probability, consecutive sampling, and allocated equally to the ONCAB and OPCAB groups. Baseline demographic characteristics, comorbidities, and body mass index were documented. Serum CK-MB, Troponin I, and Troponin T levels were measured preoperatively and at 1, 4, and 8 hours postoperatively. Data were analyzed using SPSS version 27. Independent t-tests and chi-square tests were applied, with p ≤ 0.05 considered statistically significant. Results: The mean age of participants was 58.4 ± 6.8 years, and 79.4% were male. Common comorbidities included hypertension (61.8%), diabetes mellitus (55.9%), and hyperlipidemia (45.6%). Baseline enzyme values were statistically comparable between groups (p > 0.05). Postoperatively, mean CK-MB, Troponin I, and Troponin T levels at 1, 4, and 8 hours were significantly higher in the ONCAB group than in the OPCAB group (p < 0.001 for all). Stratified analysis revealed no significant influence of age, gender, BMI, or comorbidities on enzyme elevation, indicating procedure-related differences. Conclusion: On-pump CABG was associated with significantly greater postoperative elevation of cardiac enzymes compared with off-pump surgery, reflecting higher myocardial injury linked to cardiopulmonary bypass. The off-pump approach may thus offer superior myocardial protection and should be considered where technically feasible, particularly in high-risk populations with prevalent cardiovascular comorbidities in Pakistan.