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The long-term influence of coronary bypass grafts on myocardial infarction and survival
Insights
Coronary artery bypass grafting significantly reduced operative mortality from 28% to under 3% in patients with angina. This procedure greatly improved or eliminated angina in 86% of survivors, demonstrating its effectiveness in improving cardiac outcomes.
Area of Science:
- Cardiovascular Surgery
- Cardiac Surgery Outcomes
- Coronary Artery Disease Management
Background:
- Coronary artery bypass grafting (CABG) has been a cornerstone treatment for severe coronary artery disease.
- Early surgical outcomes and long-term efficacy required further evaluation to optimize patient selection and technique.
Purpose of the Study:
- To review the outcomes of elective coronary artery bypass grafting for angina performed between 1968 and 1972.
- To assess changes in surgical techniques, operative mortality, graft patency, and long-term survival.
Main Methods:
- Retrospective analysis of 448 patients undergoing elective CABG for angina from 1968-1972.
- Evaluation of operative mortality, graft patency rates via late angiograms, and survival using life-table analysis.
Main Results:
- Operative mortality decreased from 28% to less than 3% over the study period.
- 86% of surviving patients experienced angina elimination or significant improvement.
- Five-year survival was 77%, with 71% graft patency rate observed in late angiograms.
Conclusions:
- Coronary artery bypass grafting demonstrates significant reduction in operative mortality and substantial improvement in angina symptoms.
- Long-term survival following CABG compares favorably to non-operative management, highlighting its therapeutic value.
- Ongoing advancements in grafting techniques, such as internal mammary artery grafts, hold promise for further improving long-term outcomes and graft patency.
Abstract:
Approximately 1,000 coronary bypass procedures were performed at New York University between February 1968 and December 1973. This report reviews all elective operations performed for angina between 1968 and 1972, a total of 448 patients. In this five-year period the percentage of diseased arteries bypassed rose from 40% to 84%, and operative mortality decreased from 28% to less than 3%. There were a total of 28 operative deaths, mostly from myocardial infarction and low cardiac output. Operability was nearly 95%. The only fixed contraindication was chronic congestive failure. Over one-half of the patients had an abnormal ventriculogram, and there was some history of mild congestive failure in nearly 20%. Elevation of left ventricular end-diastolic pressure above 20 mm before operation was associated with a higher operative mortality, but the late mortality was similar to those with a normal preoperative end-diastolic pressure. In 383 surviving patients, angina was eliminated or greatly improved in 86%, unimproved in 12% and worse in 2%. Late angiograms were performed on 201 patients, studying a total of 445 venous grafts with an overall patency rate of 71%. Graft occlusion was sporadic and unpredictable, but over 90% of patients with multiple grafts remained with at least one patent graft. A late myocardial infarction occurred in 32 out of 420 patients surviving operation, and was fatal in eight. The cumulative incidence over a period of five years was 17%. Twenty-three deaths occurred following discharge from the hospital. Life-table analyses showed a five-year survival of 77% when all deaths were included, and a five-year cardiac survival of 81% when non-cardiac deaths were withdrawn alive at the time of death. The expected survival in a comparable population group without coronary disease was 92%, while data published by Sones of patients treated without operation showed a five-year cardiac survival of 66%. Current operative techniques have an operative mortality of 2-3% and a subclinical infarction rate of 5-10%. The ideal graft is yet evolving, but data with internal mammary artery grafts are most encouraging. A future goal should be a five-year graft patency of at least 80%. Because many infarcts probably develop from a relatively small decrease in coronary blood flow, either during rest or mild activity, the likelihood that future data will demonstrate a marked increase in longevity with bypass grafting is great.