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Do coronary artery bypass operations prolong life?
Insights
Coronary artery bypass surgery improves survival for some patients with coronary artery disease, particularly those with left ventricular dysfunction. For most patients, limiting angina symptoms is the primary reason for surgery due to small survival differences.
Area of Science:
- Cardiovascular Surgery
- Interventional Cardiology
- Clinical Trials
Background:
- The survival benefit of coronary artery bypass operations for patients with coronary artery disease has been debated, especially in those without left main stenosis.
- Previous studies lacked sufficient control for patient risk factors and cohort heterogeneity.
Purpose of the Study:
- To evaluate the long-term survival benefits of coronary artery bypass surgery compared to medical management in various patient subgroups.
- To clarify the role of coronary artery bypass surgery in patients with different severities of coronary artery disease and left ventricular function.
Main Methods:
- Analysis of data from large-scale clinical studies, including randomized trials like the Veterans Administration Cooperative Study, European Coronary Surgery Study Group, and Coronary Artery Surgery Study (CASS).
- Subgroup analysis based on the number of diseased coronary arteries and the degree of left ventricular dysfunction.
Main Results:
- Coronary artery bypass surgery prolonged survival only in high-risk subgroups, specifically those with symptomatic left main coronary artery stenosis and those with double- and triple-vessel disease and left ventricular dysfunction.
- Survival with single-vessel disease is excellent with medical management and not improved by surgery.
- Medically treated patients with double- and triple-vessel disease and good left ventricular function generally have >85% five-year survival, with limited evidence of improvement from surgery.
Conclusions:
- Coronary artery bypass surgery offers survival benefits primarily for symptomatic patients with left main coronary artery stenosis and those with double- or triple-vessel disease coupled with left ventricular dysfunction.
- For patients with less severe disease or good left ventricular function, the survival benefits of surgery are minimal, making symptom management the primary indication.
- Ongoing improvements in surgical techniques may influence future survival differences, but current evidence suggests limiting angina is key for individual patient decisions.
Abstract:
Coronary artery bypass operations improve survival in patients with symptomatic left main coronary artery stenosis, but whether or not longevity is improved in other patients has been controversial. Small clinical studies, even when randomized, have not sufficiently controlled for the heterogeneous distribution of risk factors in patient cohorts treated medically and surgically. The first randomized study large enough to overcome such problems, the Veterans Administration Cooperative Study, showed that coronary artery bypass procedures prolonged survival only in the high-risk subgroup. The surgically treated patients suffered more perioperative morbidity and mortality and had worse long-term survival than similar patients operated on in more recent years. The European Coronary Surgery Study Group recently reported that the three-year to five-year survival of symptomatic patients with triple-vessel disease and normal left ventricular function was better if patients were randomly assigned to surgical therapy. The third and by far the largest randomized study, the Coronary Artery Surgery Study (CASS), has not yet reported long-term follow-up results. Large clinical studies, both randomized and nonrandomized, that have subgrouped patients by the number of diseased coronary arteries and by the degree of left ventricular dysfunction all show that survival with single-vessel disease is excellent and not improved by operation. Medically treated patients with double- and triple-vessel disease who have good left ventricular function generally now have a five-year survival greater than 85 percent and only two of the major studies suggest that it is improved by operation. The results of most studies, however, suggest that bypass operation prolongs survival in symptomatic patients when left ventricular dysfunction coexists with double- and triple-vessel disease. Continually improving surgical techniques may potentiate the small survival differences that are now apparent, but until then, because the survival differences are so small, it is recommended that limiting anginal symptoms remain the primary indication for a coronary bypass procedure for an individual patient.