Salutary effects of myocardial ischemia in coronary artery disease

Although myocardial ischemia in patients with coronary artery disease should be eliminated with medical and surgical treatment, it paradoxically contributes to the preservation of compromised myocardium through various mechanisms. First, ischemic vasodilation of coronary and collateral vessels resulting from the activation of the ATP-sensitive K+ channel maximizes a blood supply to the area having imbalance between myocardial oxygen supply and demand. Second, myocardial ischemia secondary to severe coronary stenosis develops functionally significant collateral circulation, which alleviates the deleterious sequelae of coronary obstructive disease. Finally, myocardial preconditioning with ischemia attenuates the subsequent ischemic insult. Particularly if combined with early reperfusion of the infarct-related coronary artery, the infarct size is decreased to one fourth of the permanent occlusion in dogs. A thorough understanding of the mechanisms of self-protecting benefits of myocardial ischemia would be useful in the care of patients with coronary artery disease.