Objective: To analyze the difference in coronary artery bypass grafting (CABG) performed with normothermic cardiopulmonary bypass (CPB) and CABG supported with the intracardiac microaxial pump (ICP, Impella, Aachen, Germany). Methods: A prospective randomized study was conducted in seven centers. The study population consists of 199 patients undergoing isolated primary CABG (CPB group 94 patients, ICP group 105 patients). Both groups are equal in demographic variables, number of bypasses performed, and Euroscore predicted mortality. We analyzed clinical outcome, myocardial enzymes and blood parameters of hemolysis, organ function and inflammatory response. Results: Seventeen patients (16%), randomized in the ICP group, were switched to the CPB group. This was due to the inability to position the right side catheter adequately (n=8), to a pump failure (n=1) or to the perioperative decision that beating heart surgery is technically not possible (n=8). There was no significant difference between the two study arms regarding the pump assistance time (CPB 67.1±22.9 min; ICP 67.7±30.3 min; P=0.88861), the number of grafts (CPB 2.4±0.7; ICP 2.3±0.8) and the number of grafts to the back wall (CFX; both groups n=37). There is no significant difference in clinical outcome, evolution of myocardial enzymes, indices of organ function and hemolysis. There is a reduced inflammatory response in the ICP group as indicated in the postoperative release of granulocyte elastase (CPB 259±195; ICP 150±126 μg/l; P≪0.00001) and complement C3 (CPB 0.73±0.2; ICP 0.65±0.2 g/l; P=0.008). Conclusion: The intracardiac pump for the right heart is difficult to introduce. As a consequence the right side pump underwent design modifications. There were no differences in clinical outcome between both groups. The inflammatory response is significantly reduced in the ICP group.