Clinical Alert: Bypass Over Angioplasty for Patients with Diabetes
That rigorous investigation -- the BARI study -- tests whether the use of PTCA as an initial treatment compromised the clinical outcome for patients with multivessel coronary artery disease who needed revascularization and could be treated by either PTCA or CABG. BARI did not test outcomes for repeat procedures. It also studied only PTCAs performed with the standard balloon technique.
The trial is the largest randomized study of its type, with enough patients to be able to address key endpoints, both overall and in predetermined patient subgroups. The subgroups were based on patients' anginal status, number of diseased vessels, and left ventricular function. Also studied are various demographic factors such as gender, age, race, and the presence of diabetes.
The primary endpoint is mortality after 5 years of follow-up. Other important endpoints include the occurrence of a myocardial infarction, need of repeat revascularization procedures, angina, functional status, quality of life, and utilization of health-care resources. (Both quality of life and utilization of health-care resources are studied in detail in a separately funded ancillary study.)
Patients were eligible for the trial if they had coronary artery disease with a 50 percent or more luminal obstruction (as measured by calipers) in at least two of the coronary vessels supplying two or three major coronary territories. They also had to have clinically severe ischemia but not a prior revascularization. Patients were ineligible for the trial if they had, for example, insufficient angina or ischemia, required emergency revascularization, left main stenosis of 50 percent or greater, a noncardiac illness expected to result in limited survival, primary coronary spasm, or a poor quality angiogram. Baseline angiograms were reviewed and classified by the Central Radiographic Laboratory (Dr. Edwin L. Alderman, director) at the Stanford University Medical Center in Palo Alto, CA.
Between August 1988 and August 1991, 18 clinical centers randomized 1,829 patients, ages 17 to 80 and including 353 on drug treatment for diabetes. Half of the patients were randomly assigned to PTCA and the other half to CABG. At baseline, the mean age of the randomized patients was 61 years. Thirty-nine percent of the randomized patients were age 65 or older, 27 percent were women, 25 percent were classified as having diabetes (of these, 76 percent were being treated with oral hypoglycemic agents or insulin), 60 percent had two-vessel disease and 40 percent had three-vessel disease, and 98 percent had angina (of these, 64 percent had unstable angina and 17 percent had class 3-4 angina). At the time of this alert, 66 percent of patients had completed follow-up. Patients will be followed for a minimum of 7 years. The trial is expected to finish follow-up on all patients by November 1998.
Follow-up includes annual functional status assessments and an electrocardiogram (ECG), and a biennial exercise stress test. As required by the protocol, risk factor modification was initiated for all patients after their enrollment. This includes help with smoking cessation, exercise, and diet. Patients also were treated as needed for hypertension, elevated blood cholesterol, and diabetes. Risk factors and medical problems were managed by each patient's primary care physician.