VA Coronary Artery Bypass Surgery Cooperative Study Group - VA Coronary Artery Bypass Surgery Cooperative Study Group

Description:

Medical vs surgical therapy for stable angina.

Hypothesis:

To compare bypass surgery (CABG) with medical therapy in patients with stable angina.

Study Design

Study Design:

Patients Screened: Not reported
Patients Enrolled: 686
NYHA Class:
Mean Follow Up: Average 11.2 years
Mean Ejection Fraction: Assessed by left ventriculography

Patient Populations:

Stable angina pectoris of >6 months’ duration and receiving medical therapy for three months and with resting or exercise ECG evidence of myocardial ischemia

Exclusions:

MI in prior 6 months, unstable angina, DBP >100 mm Hg, uncompensated congestive heart failure, left ventricular aneurysm or other serious cardiac disease, serious comorbidity with life expectancy <5 years

Primary Endpoints:

All-cause mortality.

Secondary Endpoints:

Myocardial infarction, severity of angina

Drug/Procedures Used:

CABG surgery or medical therapy.

Concomitant Medications:

Nitrates, beta-blockers, and other medications allowed for symptomatic relief of angina.

Principal Findings:

At 7 years, the CABG group had a significantly lower mortality compared to the medical therapy group (23% survival vs. 30%, p=0.043) but this benefit did not persist at 11 years (42% vs. 43%). There was no benefit at 7 or 11 years in patients without left main disease. At 11 years, surgery was beneficial in the following subgroups: 1.) three-vessel disease plus left ventricular dysfunction (50% vs. 62% mortality, p=0.026), 2.) clinically high-risk patients with 2 or more of the following: resting ST depression, history of MI, history of hypertension (51% vs. 64%, p=0.015) and 3.) combined angiographic and clinically high risk (46% vs. 76%, p = 0.005). High risk was defined as two or all of the following: ST depression of resting ECG, history of MI, history of hypertension. Patients with left ventricular dysfunction (ejection fraction <45%, end-diastolic pressure >14 mm Hg, or any contraction abnormality) benefited from surgery at 7 years (26% vs. 37%, p = 0.049) but not at 11 years (47% vs. 51%). Of note, the 30-day operative mortality rate is 5.8%. A subsequent 18-year follow-up report showed no benefit of surgery, even in the high-risk subgroups. Overall, the benefits of surgery began to diminish after 5 years, a time course that parallels the development of graft disease.

Interpretation:

Among high risk patients with stable ischemic heart disease, in this early trial, surgical treatment provided an early mortality benefit. The benefits of surgery began to diminish after 5 years, a time course that parallels the development of vein graft disease. However, it is important to note that this study was undertaken prior to the common use of arterial conduit(s) such as the left internal mammary artery. It was also undertaken before the availability of stents and glycoprotein 2b3a inhibitors.

References:

N Engl J Med 1984; 311: 1333-9. Circulation 1992; 86: 121-130. 18 year follow-up.

Clinical Topics: Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, Prevention, Stable Ischemic Heart Disease, Hypertension, Chronic Angina

Keywords: Myocardial Ischemia, Follow-Up Studies, Angina, Stable, Nitrates, Blood Pressure, Electrocardiography, Ventricular Dysfunction, Left, Hypertension, Stents


< Back to Listings