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Significance of silent myocardial ischemia after coronary artery bypass surgery
1Evans Memorial Department of Clinical Research, University Hospital, Boston, Massachusetts 02118.
Insights
Transient myocardial ischemia is common after coronary artery bypass grafting (CABG). Both silent and symptomatic ischemia detected post-CABG are linked to significantly lower long-term survival rates.
Area of Science:
- Cardiology
- Cardiac Surgery
- Clinical Research
Background:
- Transient myocardial ischemia can occur after coronary artery bypass grafting (CABG).
- The prognostic significance of post-CABG ischemia requires further evaluation.
Purpose of the Study:
- To evaluate the prevalence of transient myocardial ischemia after CABG.
- To assess the prognostic significance of ischemia detected post-CABG.
Main Methods:
- Systematic review and meta-analysis of studies evaluating ischemia after CABG.
- Ambulatory electrocardiographic monitoring and exercise testing were used to detect ischemia.
- Analysis of survival data from the Coronary Artery Surgery Study (CASS) randomized patient subsets.
Main Results:
- An average of 24% of patients showed ischemia via ambulatory electrocardiographic monitoring 3-12 months post-CABG.
- An average of 36% of patients experienced ischemic ST-segment depression during exercise testing 4-50 months post-CABG.
- Seventy-seven percent of these ischemic episodes were silent during exercise testing.
- In the CASS study, patients with ischemia (silent or symptomatic) at 6 months post-CABG had significantly lower 12-year survival.
Conclusions:
- Transient myocardial ischemia is a frequent finding after CABG.
- The presence of ischemia, particularly silent ischemia, following CABG is associated with reduced long-term survival.
- Routine monitoring for ischemia post-CABG may be important for risk stratification.
Abstract:
The prevalence and prognostic significance of transient myocardial ischemia after coronary artery bypass grafting (CABG) were evaluated. In 3 studies, ischemia was found in an average of 24% of patients by ambulatory electrocardiographic monitoring at 3-12 months after CABG. An average of 36% of patients in 3 other studies experienced ischemic ST-segment depression during exercise testing at 4-50 months after CABG. Of the ischemic episodes, 77% were silent during exercise testing. In the Coronary Artery Surgery Study (CASS) randomized patient subsets, survival at 12 years was significantly lower for patients who had either silent or symptomatic ischemia during exercise testing at 6 months after CABG compared with those who had no ischemia.