Annexin V Levels in Young Patients with Acute Myocardial Infarction: New Answers Bring New Questions

Rev Esp Cardiol 2002;55(12):1223-5 1223 The sharp reduction in coronary blood flow produced by a thrombus generally precipitates acute or unstable coronary syndromes (ACS). Unlike venous thrombosis, arterial thrombosis takes place in areas where the vessel wall is damaged in some way. In the coronary arteries, the lesion usually is a fissured or ruptured atheroma plaque, endothelial denudation of an atherosclerotic lesion, or, as recently reported, a calcified eruptive nodule.1 However, only a small percentage of the coronary lesions associated with thrombosis (complicated lesions) originate clinical manifestations. Postmortem studies of young patients who die from non-cardiovascular causes have demonstrated ruptured or simply eroded coronary plaques on which thrombi have formed that do not limit coronary flow and do not cause acute clinical manifestations.2,3 Generally speaking, these thrombi, known as mural thrombi, show monocyte-macrophage invasion, are organized, and incorporated into the underlying plaque that further protudes into the vascular lumen. Repetition of this process is one of the mechanisms by which atheroma plaques progressively narrow the coronary lumen.4 Nevertheless, sometimes the mural thrombi serves as a basis for a new thrombosis originated days after formation, giving rise to an unstable coronary syndrome.4 What factors influence the final size and attendant clinical manifestations of a coronary thrombus? The degree of thrombosis will depend on the balance between anticoagulant and procoagulant activity present in a given moment. On the one hand, the type of vascular lesion has an influence as a prothrombotic factor: for example, a large plaque rupture that exposes the lipid nucleus to circulating blood is an important thrombotic stimulus that would give rise to a larger, possibly occlusive, thrombus. Another important factor is the thrombogenicity of the blood, understood as the amount of thrombus that an individual develops in resED I TO R I A L S