Proportion of fibrin and platelets differs in thrombi on ruptured and eroded coronary atherosclerotic plaques in humans

Objective: To determine the proportion of platelets and fibrin in coronary thrombi. Design: Immunohistochemical and morphometric means to examine the coronary arteries of 31 patients who died of acute myocardial infarction. Results: Fresh thrombi were detected in the feeding arteries of infarction areas in 23 cases (74%) and were associated with plaque rupture in 18 (78%) and plaque erosion in 5 (22%). An immunohistochemical study showed that the thrombi consisted of a mixture of fibrin and platelets as well as some other types of blood cells. The fibrin and platelet positive areas in the thrombi associated with plaque rupture accounted for 74 ( 19)% and 35 ( 20)% ( p< 0.01) and those associated with erosion accounted for 51 ( 6)% and 70 ( 21)%, respectively, of the total areas. Areas of positive immunoreactivity for tissue factor and C reactive protein were also significantly greater in ruptured than in eroded plaques. Conclusion: These results indicate that the proportions of fibrin and of platelets differ in coronary thrombi on ruptured and eroded plaques. Higher proportions of tissue factor and C reactive protein contribute more significantly to thrombus formation on plaque rupture than on plaque erosion.