Individual and combined effects of ischemic conditioning strategies on infarct size after myocardial ischemia reperfusion

Ischemic preconditioning (PreC), remote perconditioning (PerC), and postconditioning (PostC) are known to reduce myocardial infarct size, but their relative efficacy and potential additive effects remain unclear. This study compared the individual and combined effects of PreC, PerC, and PostC on infarct size and cardiac troponin I (cTnI) levels in a rat model of myocardial ischemia-reperfusion. Fifty-four male Sprague-Dawley rats underwent 40 min of coronary occlusion followed by 2 h of reperfusion. They were randomized into six groups: Control, PreC, PerC, PostC, PerC + PostC, or PreC + PerC + PostC. Infarct size was measured using Evans blue/TTC staining, and cTnI levels were assessed. All conditioning strategies significantly reduced infarct size and cTnI levels compared to control (p < 0.001). PreC and PreC + PerC + PostC were the most effective, while PostC was the least. No additive benefit was seen when combining PreC with other strategies (p = 0.9) or PerC with PostC (p = 0.9). These findings suggest that PreC provides the greatest cardioprotection, and combining conditioning strategies does not enhance outcomes, possibly due to overlapping protective mechanisms.