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Determinants of risk for coronary artery bypass grafting in stable and unstable angina pectoris
Insights
Predictors for operative mortality and morbidity after coronary artery bypass grafting (CABG) vary between stable and unstable angina patients. Understanding these risk factors improves patient outcomes.
Area of Science:
- Cardiology
- Cardiac Surgery
- Clinical Risk Analysis
Background:
- Coronary artery bypass grafting (CABG) for chronic stable angina has low operative risk.
- Clinical and angiographic factors can predict varied outcomes in patient subsets undergoing CABG.
Purpose of the Study:
- To identify clinical and angiographic predictors of operative mortality and morbidity in patients undergoing CABG.
- To analyze risk factors based on patient clinical presentation (stable vs. unstable angina) and surgical timing (elective vs. urgent).
Main Methods:
- Prospective recording of 45 variables in 1302 patients undergoing CABG.
- Analysis of 12 selected variables using univariate and multivariate techniques.
- Stratification of patients into stable/unstable angina and elective/urgent surgery groups.
Main Results:
- Unstable angina patients had four mortality predictors (sex, age, left ventricular function, left main coronary stenosis >50%); stable patients had three (sex, age, left ventricular function).
- Morbidity predictors for unstable patients included sex, age, left ventricular function, surgery timing, coronary artery disease extent, and myocardial protection type.
- Stable patients had three morbidity predictors, identical to their mortality predictors.
- Operative mortality: 2.9% (stable) vs. 5.4% (unstable). Perioperative infarction rate: 9.1% (stable) vs. 13.7% (unstable).
Conclusions:
- Determinants of operative risk differ significantly between stable and unstable angina patients undergoing CABG.
- Risk factor analysis stratified by clinical presentation and surgical urgency enhances understanding of CABG outcomes.
- Identification of specific predictors allows for tailored risk assessment and management strategies in CABG patients.
Abstract:
Although the operative risk and morbidity associated with coronary artery bypass grafting for chronic stable angina is exceptionally low, clinical and angiographic factors exist that may predict differing outcomes in patient subsets. Forty-five variables were prospectively recorded on all 1302 patients who underwent coronary artery bypass grafting at Toronto General Hospital over a 24-month period. Twelve selected variables were analysed by univariate and multivariate techniques. The patients were divided in two groups depending upon their clinical presentation (stable versus unstable angina) and the timing of surgery (elective versus urgent). The results of risk-factor analysis revealed that the unstable cohort had four predictors for operative mortality: sex, age, left ventricular function and left main coronary stenosis greater than 50%, whereas the stable cohort had only three predictors: sex, age and left ventricular function. The results for postoperative morbidity (perioperative myocardial infarction or low-output syndrome) showed that the unstable cohort had six predictors: sex, age, left ventricular function, timing of surgery, extent of coronary artery disease and the type of myocardial protection used. The stable cohort had only three predictors of morbidity, the same as for mortality. This analysis of multiple risk factors on patients grouped according to stability and timing of surgery clearly demonstrated determinants of risk in the two groups (operative mortality for the stable group of 2.9% versus 5.4% for the unstable group, and perioperative infarction rate for the stable group of 9.1% and for the unstable group of 13.7%).