Coronary artery surgery study (CASS): a randomized trial of coronary artery bypass surgery. Survival data.

Open Access
Publisher Website
Google Scholar
Abstract
CASS [coronary artery surgery study] includes a multicenter patient registry and a randomized controlled clinical trial. It is designed to assess the effect of coronary artery bypass surgery on mortality and selected nonfatal end points. Patients (780) with stable ischemic heart disease were randomly assigned to receive surgical (n = 390) or nonsurgical (n = 390) treatment and were followed. At 5 yr, the average annual mortality rate in patients assigned to surgical treatment was 1.1%. The annual mortality rate in those receiving medical therapy was 1.6%. Annual mortality rates in patients with single-, double- and triple-vessel disease who were in the surgical group were 0.7%, 1.0% and 1.5%; the corresponding rates in patients in the medical group were 1.4%, 1.2% and 2.1%. The differences were not statistically significant. Nearly 75% of the patients had entry ejection fractions of at least 0.50. The annual mortality rates in patients in the surgical group in this subgroup with single-, double- and triple-vessel disease were 0.8%, 0.8% and 1.2% and corresponding rates in the medical group were 1.1%, 0.6% and 1.2%. The annual rate of bypass surgery in patients who were initially assigned to receive medical treatment was 4.7%. The excellent survival rates observed both in CASS patients assigned to receive medical and those assigned to receive surgical therapy and the similarity of survival rates in the 2 groups of patients in this randomized trial lead to the conclusion that patients similar to those enrolled in this trial can safely defer bypass surgery until symptoms worsen to the point that surgical palliation is required.