Heart bypass or coronary artery bypass graft (CABG, pronounced cabbage) is a surgery that may become necessary when the arteries that supply blood and oxygen to the heart muscle become hardened and narrowed. This procedure treats blocked heart arteries by using arteries or veins from other parts of the body, called grafts, to create new passages for blood to flow to the heart muscle.

CABG is a relatively common procedure that requires expertise with the use of complex equipment; technical errors while using this equipment may lead to significant complications such as heart attack, stroke or death.  

A hospital that performs a higher volume of CABG may have more expertise with those procedures, which may result in less of a likelihood of complications. Therefore, a hospital that performs more CABG may have better outcomes for patients that undergo this procedure. The CABG volume measure should be used in conjunction with the CABG mortality measure.