Pathophysiology of Coronary Heart Disease and Biological Mechanisms for the Cardioprotective Effects of Regular Aerobic Exercise

Abstract

Atherosclerosis, the underlying cause of coronary heart disease (CHD), is a chronic inflammatory condition involving the subendothelial layer of coronary as well as other large-and medium-sized arteries. This disease process is initiated early in life by multiple risk factors. Endothelial dysfunction and lipid infiltration are fundamental for the initiation and progression of the atherosclerotic process. After many asymptomatic decades, acute coronary syndromes are generally triggered by a coronary occlusion, caused by a thrombosis initiated by disruption of a vulnerable lipid-laden plaque with a thin, noncalcified fibrosis cap. Epidemiology studies over the past 50 years have consistently observed an inverse association between CHD and regular physical activity and/or cardiorespiratory fitness. Supporting evidence of causative relationships has been provided by exercise training studies demonstrating multiple, plausible, cardioprotective, biological mechanisms. These pleotropic effects may be classified as (1) direct antiatherosclerotic effects and indirect effects via reduction of other risk factors, (2) anti-ischemic effects by decreasing myocardial oxygen demands and increasing its vascular supply and by decreasing the severity of ischemic injuries by direct conditioning effects on cardiomyocytes, (3) antiarrhythmic effects by improving electrical stability of the heart, and (4) antithrombotic (and prothrombolytic) effects, reducing risk of a coronary thrombotic occlusion. It is concluded based on an impressive body of evidence that regular aerobic exercise attenuates the risk of CHD at all stages of the atherothrombotic process.