In this study, experiments were designed to determine whether microRNAs (miRNAs) play a role in the regulation or modulation of cardiomyocytic reactions under cardioplegia-induced cardiac arrest during cardiopulmonary bypass. MicroRNAs play powerful and unexpected roles in numerous cardiovascular diseases. MicroRNA-based therapeutics may provide a unique opportunity to translate this knowledge into the clinical setting. Sprague-Dawley rats (10 per group) were randomly divided into three groups: control, perfusion, and arrest groups. In the perfusion group, isolated hearts were perfused with oxygenated physiologic buffered solution for 3 h using a Langendorff apparatus. In the arrest group, cold crystalloid cardioplegia solution was used to induce and maintain cardiac arrest for 1 h; hearts were reperfused for 2 h with warm oxygenated phosphate-buffered saline solution. Cardiac miRNAs and protein expression patterns were detected using miRNA arrays and two-dimensional fluorescence difference gel electrophoresis followed by matrix-assisted laser desorption/ionization-time of flight mass spectrometry. Of 103 different miRNAs and 222 different proteins expressed in the three groups, miRNA-27a was the one considered to be related to the regulation of cardiomyocyte apoptosis by targeting the interleukin 10 pathway. Transfection of H9c2 cardiomyocytes with pre-miRNA-27a, which significantly decreased the mRNA and protein levels of interleukin 10 and increased expression of nuclear factor κB and its downstream cytokines during hypoxia/reperfusion injury, could activate caspase 3 and apoptosis. Our study demonstrated the altered expression of miRNAs in cardiomyocytes during cardioplegia-induced cardiac arrest. The involvement of miRNAs in cardiomyocytic apoptosis adds another level of complexity to gene regulation, which could open up novel avenues for cardiac protection strategies during cardiac surgery.