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Relation of exercise-induced myocardial ischemia to cardiac and carotid structure
P M Okin1, M J Roman, J E Schwartz
1Department of Medicine, The New York Hospital-Cornell Medical Center, New York 10021, USA. pokin@mail.med.cornell.edu
Insights
Myocardial ischemia detected during exercise stress tests is linked to carotid atherosclerosis and left ventricular abnormalities, even without apparent coronary disease. This suggests a connection between these conditions in cardiovascular health.
Area of Science:
- Cardiovascular Medicine
- Diagnostic Cardiology
- Vascular Biology
Background:
- Carotid atherosclerosis is linked to coronary artery disease and left ventricular hypertrophy.
- Carotid structural abnormalities correlate with left ventricular geometry and structure.
- The relationship between exercise-induced ST depression and carotid/left ventricular structure is not well understood, especially in asymptomatic individuals.
Purpose of the Study:
- To assess the relationship between exercise ECG myocardial ischemia and carotid atherosclerosis.
- To evaluate the association of myocardial ischemia with carotid and left ventricular structure.
- To identify predictors of exercise-induced ST depression in asymptomatic subjects.
Main Methods:
- Assessed 204 asymptomatic subjects free of clinical cardiovascular disease.
- Defined myocardial ischemia using a chronotropically adjusted ST/HR slope >3.47 microV/bpm.
- Utilized stepwise logistic regression to identify independent predictors.
Main Results:
- Myocardial ischemia was associated with a nearly threefold greater likelihood of carotid atherosclerosis.
- Ischemia correlated with older age, male sex, higher blood pressure, and increased left ventricular mass and carotid artery dimensions.
- Carotid artery cross-sectional area index and systolic blood pressure independently predicted abnormal ST/HR slope.
Conclusions:
- Subendocardial ischemia on exercise ECG is strongly associated with carotid atherosclerosis.
- This association is related to systolic blood pressure, carotid artery cross-sectional area index, and left ventricular mass index, independent of traditional risk factors.
- Findings suggest a link between ischemia and structural abnormalities in the carotid and left ventricles, potentially contributing to coronary events.
Abstract:
There is a strong relation of carotid atherosclerosis to coronary artery disease and left ventricular hypertrophy. In addition, abnormalities of carotid structure are strongly associated with abnormal left ventricular geometry and structure. However, little is known regarding the relation of exercise-induced ST depression to carotid atherosclerosis, carotid, or left ventricular structure in the absence of apparent coronary disease. The relationship of exercise ECG myocardial ischemia to the presence of carotid atherosclerosis and to carotid and left ventricular structure was assessed in 204 asymptomatic subjects free of clinical evidence of cardiovascular disease. Myocardial ischemia on the exercise ECG, defined by a chronotropically adjusted ST/HR slope of >3.47 microV/bpm, was associated with a nearly threefold greater likelihood of discrete carotid atherosclerosis (50% [6 of 12] versus 17% [29 of 192], P=.007) and with older age, male sex, higher systolic and diastolic blood pressures, greater left ventricular mass and mass index, and greater common carotid artery intimal-medial thickness and cross-sectional area index. Stepwise logistic regression analyses, including standard risk factors, revealed that only carotid artery cross-sectional area index (P=.0007) and systolic blood pressure (P=.005) independently predicted an abnormal chronotropically adjusted ST/heart rate slope. Moreover, among 132 subjects with > or = 10 microV of ST-segment depression, only left ventricular mass index and carotid artery cross-sectional area index were significant predictors of the chronotropically adjusted ST/heart rate slope response. Subendocardial ischemia on the exercise ECG is strongly associated with the presence of carotid atherosclerosis and is related to systolic blood pressure, carotid artery cross-sectional area index, and left ventricular mass index, independent of age, sex, and other cardiac risk factors. These findings provide additional insights into the relation between coronary and carotid atherosclerosis and suggest that an association among ischemia and left ventricular and carotid structural abnormalities may contribute to the pathogenesis of coronary events.