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.
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.
Older individuals without a history of overt CAD.