The Effect of Exercise Training on Mental Stress-Induced Silent Ischemia
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Coronary artery disease (CAD) remains the leading cause of death in the elderly. Silent myocardial ischemia (SI) is a manifestation of CAD in which there is a transient alteration in myocardial perfusion, function, and/or electrical activity not accompanied by chest pain. Mental and emotional stress, in particular hostility and anger are potent inducers of SI, Individuals with SI are at a 3-5 fold higher risk for the development of angina, myocardial infarction and death than subjects without SI.
Condition or disease
The hypothesis of this study is that older individuals with occult cad, mental stress/ emotional arousal (anger) increases sympathetic nervous system activity resulting in vasoconstriction thereby eliciting transient episodes of SI. Therefore an aerobic exercise intervention that reduces the response to anger/hostility and improves vascular compliance will decrease the ischemic burden in SI patients. The specific objectives are: To determine if non-smoking older individuals with exercise-induced SI have increased vasoreactivity (blood pressure, heart rate) responses to the laboratory presentation of mental stressors, decreased vascular compliance and brachial artery endothelial reactivity compared to matched non-ischemic controls; 2) To perform a randomized clinical trial that will examine the effects of 9 months of aerobic exercise training versus usual care on vasoreactivity, vascular compliance and ischemic burden on Holter monitor. Older individuals without a history of overt CAD will be recruited and evaluated for the presence of exercise-induced SI. Baseline cross-sectional comparisons of vasoreactivity and cardiovascular function will be performed between those with SI and non-ischemic controls. The individuals with SI will be enrolled in a randomized clinical trial of exercise vs usual care. Exercise treadmill testing with measurement of maximal aerobic capacity will be used to determine fitness. Vasoactivity will be quantified during a mental stress test with real time 2d echo imaging. Vascular function will be assessed using high frequency ultrasound measurements of flow-mediated brachial artery endothelial reactivity.
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