Recently the Symmetry Bypass System (SJM, St. Paul, MN) became available. Now the system is frequently applied for vein-graft to aorta anastomoses in off-pump coronary artery bypass operations. This report describes a complication associated with the use of the Symmetry Bypass System (SJM) in a patient undergoing a standard off-pump coronary artery bypass procedure. A novel imaging system (SPY, Novadaq, Toronto, Canada) was applied for intraoperative assessment of graft function, and this system immediately diagnosed the occlusion of the proximal mechanical anastomosis caused by a mobile atheromatous aortic plaque.