Bypass Angioplasty Revascularization Investigation (BARI)

BACKGROUND:

The management of patients with symptomatic coronary heart disease has evolved considerably in the past twenty years with the application of invasive techniques in an ever increasing proportion of patients.

With refinements in CABG surgery over the past twenty years, operative myocardial revascularization is feasible in most patients with myocardial ischemia. Several multicenter, randomized trials have been reported, comparing medical with surgical management in patients with coronary artery disease. Based on the three largest trials and an extensive observational literature, a consensus appears to be emerging regarding the circumstances under which medical or surgical management appears to be the method of choice.

It is clear that CABG relieves angina in the vast majority of patients with severe symptoms. It is also apparent that this procedure can be performed with very low risk by experienced operative teams. Thus, CABG is indicated for patients with suitable coronary anatomy who have severe angina refractory to medical therapy and those with significant obstruction of left main coronary artery.

The timing of operative intervention in patients with less severe angina is a point of some dispute at present. It is, however, apparent that certain categories of patients have improved survival after elective bypass surgery. These categories include patients with left main coronary stenosis, triple vessel disease with modestly impaired ventricular function, and possibly other clinically defined high risk patients. The remaining patients with mild, symptomatic coronary disease, it would appear, can afford to defer operative intervention until such time as symptoms worsen and require palliation.

Long-term information is available on some patients who had CABG in the early 1970s. By ten years substantial progression of disease is present in both the native coronary circulation and in the bypass grafts. Investigators have reported that as many as two-thirds of vein bypass grafts are closed or narrowed and intrinsic coronary disease has progressed in as many as one-half of non-bypassed vessels at 10 years following surgery. The timing of surgery in less severely symptomatic patients, strategies to decrease disease progression in grafted vessels and native circulation, and renewed interest in the use of the internal mammary artery to revascularize the heart are very active research issues at present.

PTCA was first applied to human coronary disease in 1977. There have been major advances in catheter design, balloon construction, and identification of both high and low risk patients for this procedure. Experienced angioplasty teams can now successfully dilate severe lesions in more than 90 percent of patients attempted. This success rate can be achieved with less than one percent operative mortality and less than five percent myocardial infarction and/or emergent coronary artery bypass graft surgery. However, as many as one-third of successfully dilated patients will experience the return of angina within the following six months to one year, reflecting restenosis of the dilated lesion. Most of these individuals can successfully undergo a second dilatation.

Thus, two quite effective interventions are available for patients with symptomatic coronary artery disease sufficient to require palliation by some mechanical means. Each has strengths and weaknesses. PTCA is relatively noninvasive, requires initially fewer hospital days and less intensive care, and preserves veins and mediastinum for CABG should it be required later. However, not all lesions present in a patient with multivessel disease can be dilated. There is substantial risk of restenosis and recurrence of symptoms, and a small but finite risk of having to undergo immediate CABG surgery following a failed PTCA, considerably increasing the risk of the surgery. CABG surgery results in more complete revascularization and relatively low short-term graft closure, and it can be done with an acute risk approximately equal to PTCA. However, it is apparent that surgical intervention does not change a patient's propensity to atherosclerosis; in ten years two-thirds of grafts have been compromised with atherosclerosis or thrombosis and there has been progression of atherosclerosis in the native, non-bypassed coronary circulation in roughly one-half of the patients. Second operations are considerably more difficult technically, carry a higher operative risk, and result in less dramatic relief of symptoms. There is a substantial population of patients with severe, symptomatic, multivessel coronary disease in whom it is unclear whether PTCA or CABG should be applied first.

In September 1984, the Workshop on Coronary Artery Bypass Graft Surgery recommended consideration of a clinical trial involving surgery and angioplasty. An NHLBI Task Force, established in January 1985, recommended that a clinical trial in multivessel coronary artery disease be considered by the Institute. The Cardiology Advisory Committee unanimously recommended the design and execution of a trial. In September 1985, the National Heart, Lung, and Blood Advisory Council discussed this clinical trial initiative and recommended it enthusiastically.

DESIGN NARRATIVE:

Patients who received coronary arteriography at the clinical units because of severe angina or unstable angina, with or without antecedent myocardial infarction, were asked to participate in the study. A total of 2,013 eligible patients who refused randomization and 422 who were ineligible on the basis of angiographic findings were asked to participate in the follow-up registry. The remaining patients were then randomized, 914 to CABG and 915 to PTCA, between August 1988 and August 1991. Baseline data included the clinical profile, 12-lead electrocardiogram, and information on coronary angiographic features, angina and functional status, medications, risk factors, and quality of life. Initial revascularization was performed within two weeks after randomization. Angiograms (baseline and sub study directed at 1 year and 5 years), and ECG's are interpreted by respective core laboratories. Scheduled multiple stages of PTCA were counted as a single procedure. New interventional devices, such as stents, were not used during the initial revascularization. Follow-up visits were conducted at the clinics at weeks four through fourteen after study entry and at one, three, and five years, with telephone contacts at six months and two and four years. The importance of risk factor modification was emphasized throughout the study to the patients and their primary physicians. The primary end point was mortality from all causes.

The trial has been extended through November 2002 to complete the minimum ten-year followup on all BARI patients, determine the relative efficacy of PTCA versus CABG in subgroups of women, Blacks, diabetics, and elderly, and assess the public health impact of BARI. In the followup, all currently enrolled patients will have annual telephone interviews. At ten years, the electrocardiogram will be obtained on all patients and blood lipid levels will be performed on randomized patients only. All hospitalizations that occurred since the last contact will be identified on the annual telephone contact. Angina will be assessed for the preceding six weeks. At each patient contact, patients will be instructed in behavior modification in the areas of smoking cessation, exercise, and diet. Angiographic studies will also be conducted as part of the ten-year follow-up. The four centers which participated in the first phase of these BARI activities will again conduct the angiograms. Patients will consist of the established cohort drawn from the randomized participants who completed one and five year angiograms.

A substudy of BARI, Study of Economics and Quality of Life (SEQOL), was initially funded by the Robert Wood Johnson Foundation to assess the impact of a specific revascularization on quality of life, functional and economic (hospital and physician charges) outcomes in patients randomized to BARI, and to examine factors other than treatments that affect these outcomes. Beginning in July 1997, support for SEQOL was assumed by the NHLBI under grant R01HL58324. The grant, ending in June 2002, extends the follow-up of the randomized SEQOL substudy cohort (752 subjects surviving as of May 1, 1996) to ten years to study the long-term determinants of cost and quality of life and to develop a model to project the impact of technologic changes on outcomes and cost of CABG and PTCA.

The study completion date listed in this record was obtained from the "End Date" entered in the Protocol Registration and Results System (PRS) record.