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Myocardial Ischemia in the Asymptomatic Older Patient
1Human Cardiovascular Studies Unit Laboratory of Cardiovascular Science, Gerontology Research Center, National Institute on Aging, National Institutes of Health, Baltimore, MD.
Insights
Detecting asymptomatic coronary artery disease (CAD) is crucial. Combining exercise stress tests with thallium scans effectively identifies high-risk older adults prone to cardiac events.
Area of Science:
- Cardiology
- Geriatric Medicine
- Diagnostic Imaging
Background:
- Coronary artery disease (CAD) affects a significant portion of older adults.
- Many individuals have asymptomatic coronary artery stenoses, detectable only by inducible myocardial ischemia.
- Identifying asymptomatic individuals at high risk for coronary events is a major challenge.
Purpose of the Study:
- To identify high-risk asymptomatic individuals with coronary artery disease.
- To evaluate strategies for predicting future coronary events in older adults.
- To assess the utility of exercise stress testing and thallium-201 scintigraphy.
Main Methods:
- Utilized data from the Baltimore Longitudinal Study of Aging (BLSA).
- Employed serial treadmill exercise testing and thallium-201 perfusion scans.
- Analyzed ST segment response and perfusion defects to predict coronary events.
Main Results:
- Serial changes in ST segment response alone did not improve prediction of coronary events.
- Combining ischemic ST segment depression with thallium-201 perfusion defects identified a high-risk subgroup.
- This high-risk subgroup had a 48% incidence of coronary events over a 4.6-year follow-up.
Conclusions:
- Exercise stress testing combined with thallium-201 scintigraphy is effective in identifying high-risk asymptomatic older adults.
- This combined approach aids in predicting future coronary events like myocardial infarction and sudden death.
- Further research into the pathophysiology, risk factors, and treatment of silent myocardial ischemia is warranted.
Abstract:
Although clinically manifest CAD is present in about one-fourth of individuals older than 65 years, a like proportion of additional persons have asymptomatic coronary artery stenoses, manifest only by inducible myocardial ischemia. A major challenge to contemporary cardiology is to detect the subset of such asymptomatic subjects at highest risk for future coronary events, especially myocardial infarction and sudden death. In the BLSA, we have employed various strategies toward this goal. In apparently healthy BLSA men and women, conversion from a normal to an ischemic ST segment response to treadmill exercise testing on serial biennial visits did not improve the prediction of subsequent coronary events. However, the combination of ischemic ST segment depression and a segmental thallium-201 perfusion defect induced by treadmill exercise identified a small subset of asymptomatic older subjects, 48% of whom developed a coronary event over a 4.6 year mean follow up period. The pathophysiology, risk factors, and treatment of silent myocardial ischemia are also briefly reviewed.