Relation of microcirculatory thrombosis to thrombus in the proximal coronary artery: Effect of aspirin, dipyridamole, and thrombolysis

A study was designed to determine the distribution of platelets in the microcirculation of the myocardium following experimental platelet thrombosis in a major coronary vessel. Determination was made by means of 51Cr-labelled platelets and histologic examination. The results suggest that thrombosis in a major coronary artery is associated, at least in the first hours following its occurrence, with the presence of platelet thrombi in the microcirculation of the ischemic area. Pretreatment with aspirin or dipyridamole minimized significantly the extent of microcirculatory thrombosis without affecting the thrombus in the proximal coronary artery. A thrombolytic agent given after thrombus formation had a similar effect upon microcirculatory thrombosis remaining also independent of its effect upon proximal coronary artery thrombosis. There was a decrease in incidence of arrhythmias and mortality rate in the group of animals pretreated with aspirin and dipyridamole.