Effect of regular exercise on coronary endothelial function in patients with recent myocardial infarction

Physical Exercise Protects Against Endothelial Dysfunction in Cardiovascular and Metabolic Diseases

Increasing evidence shows that endothelial cells play critical roles in maintaining vascular homeostasis, regulating vascular tone, inhibiting inflammatory response, suppressing lipid leakage, and preventing thrombosis. The damage or injury of endothelial cells induced by physical, chemical, and biological risk factors is a leading contributor to the development of mortal cardiovascular and cerebrovascular diseases. However, the underlying mechanism of endothelial injury remains to be elucidated. Notably, no drugs effectively targeting and mending injured vascular endothelial cells have been approved for clinical practice. There is an urgent need to understand pathways important for repairing injured vasculature that can be targeted with novel therapies. Exercise training-induced protection to endothelial injury has been well documented in clinical trials, and the underlying mechanism has been explored in animal models. This review mainly summarizes the protective effects of exercise on vascular endothelium and the recently identified potential therapeutic targets for endothelial dysfunction.

Short-term exercise training prevents micro- and macrovascular disease following coronary stenting

The purpose of this study was to determine the effects of exercise on coronary blood flow and macrovascular atherosclerosis in response to stent deployment. Male Yucatan swine were placed on a control diet (C); on a high-fat/cholesterol diet (hypercholesterolemic; H); or on a high-fat/cholesterol diet and aerobically exercise trained (HX) starting after 36 wk on the diet. All pigs underwent coronary angiography and intravascular ultrasound (IVUS) guided placement of a bare metal stent in the circumflex coronary artery after 40 wk on diets and 3 wk later pigs underwent repeat angiography and IVUS and coronary blood flow (CBF) measurement. Average peak velocity (APV) was measured under basal conditions and in response to intracoronary application of the endothelium-independent vasodilator adenosine and the endothelium-dependent vasodilator bradykinin. There was a similar approximately 8-fold increase in total cholesterol in H and HX compared with control. Baseline CBF was increased above control and H in HX (P<0.05). At all doses adenosine-induced CBF was impaired in H, but preserved in HX. Similarly, bradykinin-induced CBF was impaired in H vs. control, yet was potentiated in HX. Microvessel density was decreased in H and preserved in HX vs. control. Native atheroma in HX was lower relative to H and control, while in-stent stenosis in HX was not different from H. Hyperlipidemia-induced microvascular dysfunction after stent deployment may be a result of reduction in microvessel density. This is the first report that short-term exercise training near the time of stenting prevents stent-induced microvascular dysfunction and attenuates native atheroma independent of changes in plasma cholesterol in this porcine model.

Clinical evidence for a health benefit from cardiac rehabilitation: an update

The recent decision by the Centers for Medicare and Medicaid Services to expand the indications for cardiac rehabilitation (CR) provides an opportunity to review the clinical evidence of the efficacy of exercise in the CR setting for patients who have experienced an acute myocardial infarction, coronary artery bypass graft surgery, stable angina, percutaneous coronary intervention, chronic heart failure, cardiac transplant, or cardiac valve repair/replacement. Evidence shows that physician-directed, exercise-based CR positively affects the basic pathophysiology of coronary artery disease, the extent of disability and level of quality of life, and the ability to potentially impact events of both morbidity and mortality. The role of CR, including regular exercise, lifestyle modification, and appropriate medical therapy, is effective in younger and older men and women with cardiac diagnoses. The efficacy of this important therapeutic modality warrants its more widespread application.

Changes in myocardial perfusion due to physical exercise in patients with stable coronary artery disease

PURPOSE

Percutaneous transluminal coronary angioplasty (PTCA) is one of the main therapy options for patients with coronary artery disease (CAD), resulting in an improvement in myocardial perfusion and exercise capacity. Nevertheless, studies have also demonstrated a positive effect of regular exercise training on myocardial perfusion and maximum exercise capacity. The aim of this study was to evaluate changes in myocardial stress perfusion after 1 year of exercise training in comparison with the effects of PTCA in patients with CAD.

METHODS

In 66 male patients with angiographically confirmed significant coronary artery stenosis in one target vessel, myocardial perfusion scintigraphy was performed at baseline and 12 months after randomisation into either a physical exercise group or a PTCA group. Circumferential count rate profiles in 16 wall segments were classified according to their relative count rate and localisation within or outside the area supplied by the stenosed vessel.

RESULTS

Ischaemic segments showed a significant improvement in myocardial count rate within the target area after 12 months in both the PTCA and the training group (PTCA group: from 76.8+/-4.9% to 86.6+/-10.9%, p=0.03; training group: from 74.0+/-7.3% to 83.7+/-10.8%, p<0.01). Outside the target area only the training group showed a significant improvement (from 77.7+/-4.4% to 91.7+/-4.8%, p<0.01).

CONCLUSION

Our data indicate a significant improvement in stress myocardial perfusion in the training group after 12 months. The ischaemia is reduced not only in the target region of the leading stenosis but also in other ischaemic myocardial areas. In contrast, after PTCA stress perfusion improves only in the initially ischaemic parts of the target area.

Improved Endothelium Dependent Vasodilation in Endurance Athletes and Its Relation With ACE I/D Polymorphism

BACKGROUND

Aerobic exercise enhances endothelium-dependent vasodilation in healthy individuals. It is thought that exercise increases nitric oxide (NO) production and decreases NO inactivation, leading to an increase in NO bioavailability. Angiotensin II and NO have important roles in maintaining vascular tone. There are polymorphisms of the angiotensin converting enzyme (ACE) gene and the presence of the deletion (D) allele has been associated with higher concentrations of circulating and tissue ACE. In this study, the relationship between endothelial function and ACE gene polymorphisms was investigated in athletes and sedentary subjects.

METHODS AND RESULTS

The study group comprised 56 endurance athletes and 46 sedentary subjects who underwent brachial artery ultrasonographic examination. ACE insertion (I) and D allele frequencies were analyzed in all patients. Baseline brachial artery diameter and resting blood flow were similar in athletes and controls (p > 0.05). The flow-mediated dilation (FMD) was 8.48+/-3.65% in athletes and 5.16+/-2.5% in controls (p = 0.0001). FMD was significantly different between ACE genotypes in the athletes (p < 0.0001): it was higher in ACE II (10.5+/-1.6%) subjects than in the DI (8.4+/-2.3%) or DD (7+/-1.2%) subgroups.

CONCLUSION

Regular isotonic exercise can improve endothelium-dependent vasodilation especially in those with the ACE II genotype.