The Effects of Exercise on Endothelial Function in Patients with Coronary Artery Disease

Abstract

1657 Although there is no direct link between endothelial dysfunction and coronary artery disease, there is evidence that the loss of normal endothelial function may contribute to the pathophysiology of coronary ischemia and the development of atherosclerosis. Despite the clear association between exercise and the reduction of coronary artery disease, the mechanism responsible for the reduction has not been elucidated. PURPOSE: The purpose of this study was to determine the effect of exercise typical to most cardiac rehabilitation programs, on endothelial-dependent vasodilatation in patients with coronary artery disease. METHODS: Participants completing this study were 14 males and 2 females (mean age 59 yrs, range 44–79 yrs) with no prior history of regular exercise. Each of the participants began this 12-week study after undergoing an angiogram that confirmed the presence of coronary artery disease. Following recruitment, participants came to the testing site for determination of their baseline endothelial function. Endothelial function was determined by measuring the brachial artery vasoreactivity following 5 min of upper arm ischemia. This measurement was done non-invasively using ultrasound. Vasodilation following upper arm occlusion was expressed relative to the average of three measurements at rest. Subjects began a monitored exercise program following their baseline measurements in which they were encouraged to exercise 3 times per week. Subjects had exercise prescribed each day they trained that was equal to a RPE of 3 (moderate) on the modified Borg RPE scale. Modalities used were treadmills, bikes, and recumbent stepping machines. Exercise was continuously monitored by exercise technicians trained in cardiac rehabilitation. RESULTS: To test the hypothesis that endothelial function improves with exercise a one-way repeated measures ANOVA was conducted. For this analysis, maximum percent change in brachial artery diameter post blood pressure cuff release following 5 min upper arm occlusion served as the dependent variable and exercise served as the independent variable. Time served as the within subjects' factor. No significant difference in the change in the brachial artery diameter was observed. CONCLUSION: These results suggest that brachial artery reactivity to increased blood flow was not altered by exercise as typically prescribed in cardiac rehabilitation programs.