There are more than 1,000 surgical groups in the U.S. that perform heart bypass surgery. About 90 percent of them provide performance data to the Society of Thoracic Surgeons, a nonprofit organization that represents doctors who operate on the chest. The groups in these ratings are those that agreed to share data with us. If a group you are interested in is not listed here, ask the heart surgeons if they would show you their results, and if they plan to share them publicly in the future. Read more about the heart bypass ratings and treating heart disease.