Objective: We aimed to evaluate whether surgical intracoronary shunt protects myocardium in patients with moderate left ventricular dysfunction (MLVD). Methods: Thirty-nine patients consisted the shunt group and 43 patients consisted the shuntless group. Troponin I, CK, and CK-MB were measured preoperatively, and at 6 and 24 h postoperatively. Cardiac enzymes, rate of postoperative atrial fibrillation (AF) and third month ejection fraction (EF) were compared between the groups. Results: There were no significant differences between the groups for preoperative troponin I, CK, CK-MB, and postoperative CK levels (at 6 and 24 h). Postoperative troponin I and CK-MB levels were significantly lower in the shunt group (p < 0.001). Although preoperative EF of the patients were not significantly different between groups, the third month EF were significantly increased in both groups, and this increment was significantly higher in the shunt group than the shuntless group. One patient (2.3%) died in the shuntless group whereas there was no death in the shunt group. Conclusion: Intracoronary shunt has protective effects on myocardium in patients with moderate left ventricular dysfunction. (c) 2008 European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved.