Can free radicals induce coronary vasospasm and acute myocardial infarction?

Spontaneous acute occlusion of the coronary artery produces regional myocardial ischemia and infarction. This coronary occlusion could be due to rapid progression of atherosclerosis or vasospasm. The factors that can precipitate an acute attack of myocardial infarction or coronary spasm are not known. It is proposed that a stress-induced rise of unesterified arachidonic acid could trigger a leukocyte respiratory burst with the release of free radicals such as superoxide anion (O2-), hydrogen peroxide, hydroxyl radical, and singlet oxygen. These free radicals have the ability to inhibit prostacyclin (PGI2) formation and enhance the breakdown of endothelium-derived vascular relaxing factor (EDRF) which are potent vasodilators and platelet anti-aggregators. This may lead to rapid progression of atherosclerosis or coronary vasospasm leading to acute myocardial infarction. If this is true, free radical quenchers and inhibitors of leukocyte oxidative burst may be useful in the prevention of progression of atherosclerosis and coronary vasospasm.