Ischemic Preconditioning as a Myocardial Protection Strategy in CABG: Evidence from a Prospective Clinical Study

Introduction: Ischemic preconditioning (IP) is a method that may help protect the human heart from injury during cardiac surgery. It is believed that IP prepares the heart for upcoming prolonged ischemia by activating local protective mechanisms. Objective: This prospective study aims to evaluate the degree of myocardial protection offered by IP compared to standard cold blood cardioplegia (CBC). Materials and Methods: Fifty patients with stable angina and coronary artery disease (CAD) scheduled for coronary artery bypass grafting (CABG) were randomized into two groups: IP (n=25) and control (n=25). In the IP group, two cycles of 2-minute ischemia followed by 3-minute reperfusion were applied before aortic cross-clamping. Blood samples were collected through a central venous catheter to measure creatine kinase-MB fraction (CK-MB), creatine phosphokinase (CPK), cardiac troponin I (cTnI), and lactate dehydrogenase (LDH). Postoperative cardiac rhythm was also monitored. Results: The release of cTnI and lactate was significantly lower in the IP group compared to the control group (cTnI p < 0.0001, CK-MB p = 0.005, CPK p = 0.005). However, there was no significant difference in LDH levels between the groups (p = 0.264). The need for defibrillation after cardiac arrest was lower in the IP group compared to the control group (18% vs. 40%). Conclusion: The role of IP in cardiac surgery remains uncertain. However, compared to CBC alone in low-risk CABG patients, IP as an adjunct to CBC reduced levels of cTnI, CK-MB, and CPK, and was associated with a lower incidence of postoperative atrial fibrillation.