Study of the mechanism involved in the beneficial effects of exercise aerobic training in patients with coronary microvascular dysfunction

Abstract

A study recently conducted in our research group showed that 4 months of aerobic exercise training promoted significant improvement of myocardial perfusion and chest pain in patients with coronary microvascular dysfunction. These original results suggested that.aerobic exercise training could be a effective therapeutic intervention in patients with coronary microvascular dysfunction. The present project aims at investigating the mechanisms by which aerobic exercise training exerts beneficial effects in patients with coronary microvascular dysfunction. We will specifically focus on the individual quantitative correlation between the reduction of reversible perfusion defects in myocardial perfusion scintigraphy and 1 - endothelium-dependent vasodilation, 2 - vascular reactivity associated with sympathetic stimulation (cold pressor test), 3 - changes in cardiac sympathetic neuronal activity by use of scintigraphic images with I123-MIBG, and 4 -changes in the cardiac sympathetic/vagal balance through analysis of the heart rate variability. Patients diagnosed with coronary microvascular dysfunction (n=60) will be prospectively investigated and divided into four research groups: Two groups will be submitted to physical training: primary microvascular ischemia group (n = 15) and Group microvascular ischemia associated with coronary atherosclerotic disease (n = 15). Two control groups (n = 15 per group) with the same characteristics, but not trained. Patients will undergo initial assessment including: myocardial perfusion scintigraphy with gated-SPECT-99Tc-sestamibi, cardiopulmonary exercise testing, evaluation of endothelial function (vasodilator response after ischemia), assessment of vascular reactivity to cold pressor test, quantitative assessment of cardiac sympathetic activity by use of myocardial scintigraphy I123-MIBG and heart rate variability. After the initial assessment, patients of the physical training groups will be submitted to aerobic physical training on a treadmill three times a week for a period of eight weeks. After this period of 8 weeks, all groups will undergo repeated evaluation employing the same methods applied at the baseline. (AU)