The coronary artery surgery study (CASS)--a randomized trial and a registry.

In 1973 the National Heart Lung and Blood Institute organized the Coronary Artery Surgery Study (CASS) including a patient registry and a randomized trial designed to compare medical and surgical therapy in patients with coronary artery disease. This study is discussed in detail and compared with two further large randomized trials of coronary artery bypass surgery, the US Veterans Administration Trial (VA) and the European Cooperative Surgical Study (ECSS). Although there are many differences between these three studies, their similarities warrant some conclusions on the improvement of survival in certain high risk patients, protection against myocardial infarction, the deterioration of graft patency, and the postponement of surgery in low risk patients.