Initial medical therapy did not adversely affect long-term quality of life in the Coronary Artery Surgery Study (CASS)
ACP J Club. 1991 Mar-April;114:38. doi:10.7326/ACPJC-1991-114-2-038
Rogers WJ, Coggin CJ, Gersh BJ, et al. Ten-year follow-up of quality of life in patients randomized to receive medical therapy or coronary artery bypass graft surgery. The Coronary Artery Surgery Study (CASS). Circulation. 1990 Nov; 82:1647-58.
To assess the effectiveness of bypass graft surgery for coronary artery disease combined with medical therapy in improving quality of life through 10 years of follow-up when compared with medical therapy alone.
Randomized controlled trial.
11 clinical sites in North America.
Patients were included if they had operable coronary arteries with lesions of ≥ 70% stenosis. Patients were excluded if they had previous coronary artery bypass graft surgery, an ejection fraction < 0.35, overt heart failure or shock as the main symptoms of myocardial ischemia, left main coronary artery stenosis ≥ 70%, angina severity of Canadian Cardiovascular Society class 3 or 4, or age > 65 years. Of 2099 eligible patients, 780 were randomized.
Assignment to coronary bypass graft surgery combined with medical therapy (n = 390) or medical therapy alone (n = 390).
Main outcome measures
Chest pain, heart failure, activity limitation, employment status, recreation, drug therapy, and hospitalization.
By 10 years after entry, coronary artery surgery had been done once or more in 93% of those assigned to surgery and 37% of those initially assigned to medical therapy. Rates of angina for the surgical and medical groups, respectively, were entry, 78% compared with 78%; 5 years, 37% compared with 62%; 10 years, 53% compared with 58%. At 10 years, there were no statistically significant differences between the treatment groups in the proportion of patients who were free from heart failure symptoms (surgery 75% vs medical 72%); who had activity limitation (34% vs 28%); or who were alive (81% vs 78%). There was less use of β-blockers and long-acting nitrates by the surgical group at 1 and 5 years, but little difference from the medical group at 10 years. No significant differences were found in recreational status, employment status, use of other medications, or hospitalization frequency.
There were no significant differences in quality of life at 10-year follow-up when initial coronary bypass graft surgery was compared with medical therapy in patients with coronary artery disease. The results reflect return of symptoms in surgically-treated patients as well as selective performance of surgery in medically-assigned patients.
Source of funding: The National Heart, Lung, and Blood Institute.
Address for article reprint: Dr. K.B. Davis, CASS Coordinating Center, University of Washington, 1107 NE 45th Street, Room 530, Seattle, WA 98015, USA.
Previous studies showed greater likelihoods of patients with coronary artery disease being free from angina and requiring less medicine at 5-year follow-up if bypass surgery is an initial treatment (1), but no differences in return to employment or rehospitalization. This follow-up report from the CASS trial confirms previous 5-year results, but the 10-year rates of angina, congestive heart failure, and physical activity limitations do not remain higher in the medical group compared with the surgical group.
Although these findings are consistent with 10-year follow-up data recently reported from the Veterans Administration Cooperative Study of Coronary Artery Surgery (2), they must be interpreted with caution. First, more than one third of patients originally assigned to medical therapy crossed over to coronary artery bypass surgery. Multiple cross-overs could result in significant overestimation of the long-term benefits of medical therapy. Second, β-blockers with potential negative effects on physical activity and heart failure were more commonly used in the medical group. The use of β-blockers rather than newer antianginal agents could lead to underestimates of the actual benefits of medical therapy.
Clinically, the important results of this study are that medical therapy can be initially used in patients with normal ventricular function provided that coronary artery bypass graft surgery is offered if anginal symptoms worsen. This selective late performance of surgery in appropriate patients will result in near equalization of quality-of-life outcomes between patients originally given surgery compared with those given medical therapy alone.
Cynthia Mulrow, MD, MSc
Audie L. Murphy Memorial Veterans HospitalSan Antonio, Texas, USA
2. Peduzzi P, Hultgren H, Thomsen J, Detre K. Ten-year effect of medical and surgical therapy on quality of life: Veterans Administration Cooperative Study of Coronary Artery Surgery. Am J Cardiol. 1987;59:1017-23.