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Usefulness of a postoperative exercise test for predicting cardiac events after coronary artery bypass grafting
S Yli-Mäyry1, H V Huikuri, K E Airaksinen
1Department of Medicine, Oulu University Central Hospital, Finland.
Insights
A postoperative exercise test has limited predictive value for cardiac events after coronary artery bypass grafting (CABG). Impaired left ventricular function is a more significant predictor of long-term outcomes post-CABG.
Area of Science:
- Cardiology
- Cardiac Surgery
- Clinical Outcomes
Background:
- Coronary artery bypass grafting (CABG) is a common procedure for managing coronary artery disease.
- Assessing long-term prognosis after CABG is crucial for patient management and risk stratification.
- Postoperative exercise testing is often used to evaluate functional capacity and identify patients at risk.
Purpose of the Study:
- To prospectively evaluate the predictive value of postoperative exercise testing for cardiac events within 5 years after CABG.
- To identify significant predictors of cardiac events and long-term prognosis following CABG.
Main Methods:
- Prospective study of 231 consecutive patients undergoing CABG.
- 5-year follow-up to record cardiac events (cardiac death, myocardial infarction).
- Analysis of exercise test parameters (duration, workload, ST-segment depression) and ejection fraction in relation to cardiac events.
Main Results:
- A low postoperative ejection fraction and diuretic treatment were significant predictors of cardiac events within 5 years post-CABG.
- Exercise test duration and maximal workload did not show significant predictive value.
- No difference in graft patency was observed between groups with and without cardiac events.
Conclusions:
- The predictive value of postoperative exercise tests for long-term cardiac events after CABG is limited.
- Impaired left ventricular function (indicated by lower ejection fraction) is a more significant prognostic factor than exercise test findings for 5-year outcomes post-CABG.
Abstract:
The predictive value of a postoperative exercise test in terms of cardiac events after coronary artery bypass grafting (CABG) was prospectively studied in 231 consecutive patients. During a 5-year follow-up there were 28 cardiac events (12%), of which 15 were cardiac deaths (13 sudden), and 13 were nonfatal myocardial infarctions. There was no difference in the rate of graft patency between groups with and without cardiac events, but ejection fraction was lower in patients with than without events (51 +/- 16% vs 58 +/- 10%; p less than 0.05). Duration of the exercise test was shorter, and maximal work load was lower in patients with cardiac events (p less than 0.05 for both). The prevalence of greater than or equal to 1 mm ST-segment depression was 22% (symptomatic in 25%, and silent in 75%) and did not differ between groups with and without cardiac events. After adjustment for prognostic variables using the proportional hazards method, diuretic treatment (p = 0.007) and a low postoperative ejection fraction (p = 0.04) remained significant for predicting the risk of cardiac events within 5 years of CABG, but exercise duration and work load did not have any significant predictive value. Thus, the predictive value of a postoperative exercise test is limited, and signs of impaired left ventricular function are of greater significance for the 5-year prognosis after CABG than are those of myocardial ischemia.