[Acute coronary syndrome-initiating factors].

Acute coronary syndrome(ACS), including acute myocardial infarction and unstable angina, is a clinical state induced by the thrombus formation following the disruption of unstable atherosclerotic plaque. Recent studies have reported that activated macrophages in the vulnerable plaques destabilize the fibrous cap by the induction of protease such as matrix metalloproteinases. Also, macrophages produce tissue factor and plasminogen-activator inhibitor type 1 those activate thrombus formation following plaque rupture. On the other hand, coronary spasm plays an important role in the pathogenesis of ACS especially in Japan. In this article, we review related factors leading to plaque rupture and erosion in the basic aspect.