Impact of Aortic Cross-Clamp Duration on Postoperative Troponin I Levels and Clinical Outcomes in Elective Coronary Artery Bypass Grafting

Abstract

Objectives: This study aimed to determine the effect of aortic cross-clamp duration on postoperative Troponin I levels in patients undergoing elective coronary artery bypass grafting (CABG) and to evaluate its association with both in-hospital and short-term clinical outcomes. Methodology: A prospective observational study was conducted at the National Institute of Cardiovascular Diseases (NICVD), Karachi, from January to August 2022. A total of 300 patients undergoing isolated elective CABG were enrolled. Aortic cross-clamp time (in minutes) and postoperative Troponin I levels (measured 12–24 hours after surgery) were recorded. Patients were stratified into groups based on Troponin I levels (<10 ng/ml and ≥10 ng/ml). Outcomes assessed included in-hospital morbidity and mortality, length of ICU and hospital stay, need for ventilation and inotropes, and 6-month cardiovascular events. Data were analyzed using SPSS version 20, with p<0.05 considered statistically significant. Results: The mean age of participants was 56.54 ± 7.58 years, and the mean cross-clamp time was 93.79 ± 24.53 minutes. Patients with Troponin I ≥10 ng/ml had significantly longer clamp times compared to those with lower levels (98.14 ± 26.59 vs. 91.74 ± 23.29 minutes, p=0.035). Elevated troponin levels were associated with prolonged ICU stay (58.69 ± 18.91 vs. 52.59 ± 12.99 hours, p=0.001), longer ventilation duration (9.25 ± 18.91 vs. 6.74 ± 2.58 hours, p<0.001), and increased need for defibrillation (p=0.032). Mortality occurred only in the high-troponin group. At 6-month follow-up, adverse cardiovascular events were more frequent in patients with elevated troponin, though not all reached statistical significance. Conclusion: Longer aortic cross-clamp duration is significantly correlated with higher postoperative Troponin I levels, which in turn predict adverse short-term outcomes after CABG. These findings emphasize the importance of minimizing clamp time as a strategy to reduce myocardial injury and improve surgical outcomes.