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Updated: Aug 10, 2026
Surgical Swine Model of Chronic Cardiac Ischemia Treated by Off-Pump Coronary Artery Bypass Graft Surgery
Published on: March 27, 2018
A randomized trial of coronary artery bypass surgery. Survival of patients with a low ejection fraction
Insights
Coronary artery bypass surgery improved survival for patients with stable coronary artery disease and reduced ventricular function. Elective bypass surgery offered better long-term survival for those with triple-vessel disease and moderate ejection fractions.
Area of Science:
- Cardiology
- Cardiac Surgery
- Clinical Trials
Background:
- Coronary Artery Surgery Study (CASS) evaluated medical vs. surgical treatment for chronic, stable coronary artery disease.
- Focus on a subset of 160 patients with reduced ventricular function (ejection fraction 0.34-0.50).
- Patients followed for an average of seven years post-randomization.
Purpose of the Study:
- To compare the efficacy of medical therapy versus surgical intervention in patients with coronary artery disease and impaired ventricular function.
- To determine if surgical treatment improves survival rates in this specific patient subgroup.
- To analyze survival differences based on disease severity (single, double, or triple-vessel disease).
Main Methods:
- Randomized controlled trial comparing medical and surgical treatment arms.
- Inclusion of 160 patients with ejection fractions between 0.34 and 0.50.
- Long-term follow-up (average seven years) to assess survival outcomes.
Main Results:
- Overall survival at seven years was 84% for the surgical group versus 70% for the medical group (P=0.01).
- Patients with triple-vessel disease and moderate ejection fractions showed significantly better survival with surgery (88% vs. 65%, P=0.009).
- No significant survival difference was observed between treatment groups for patients with single or double-vessel disease.
Conclusions:
- Elective coronary artery bypass surgery improves seven-year survival in patients with triple-vessel disease and moderate ventricular dysfunction (ejection fraction 0.34-0.50).
- Medical management may be equivalent for patients with less severe coronary artery disease (single or double-vessel disease) in this functional group.
- Findings support surgical intervention for specific high-risk subgroups within stable coronary artery disease management.
Abstract:
The Coronary Artery Surgery Study (CASS) was designed to compare medical and surgical treatment of selected patients with chronic, stable coronary artery disease. This report concerns a subset of patients with reduced ventricular function. Of 780 patients randomly assigned to medical or surgical treatment, 160 had ejection fractions above 0.34 but below 0.50 at base line and have been followed for an average of seven years. Eighty-two patients were assigned to medical therapy, and 78 to surgery; the two groups were comparable at base line with regard to prognostically important variables. At seven years, 84 per cent of patients in the surgical group were alive, as compared with 70 per cent of the medical group (P = 0.01). Nearly half the patients with impaired ventricular function had triple-vessel disease at entry; at seven years, observed survival in this group was 88 and 65 per cent for those assigned to surgical and medical treatment, respectively (P = 0.009). Survival of patients with single-vessel or double-vessel disease was similar in the two treatment groups. We conclude that patients with triple-vessel disease and ejection fractions higher than 0.34 but lower than 0.50 appear to have improved seven-year survival with elective bypass surgery.
