Background: Coronary thrombosis is the major cause of acute myocardial ischaemia but can be, albeit rarely, clinically silent. We investigated a series of autopsy hearts from hospitalized patients who died from non-cardiac causes, to detect and study coronary thrombosis.
Methods: The series consisted of 132 autopsy cases (81 men and 51 women, age range 32-39 years, mean 63 +/- 14), in whom cause of death was confirmed as extracardiac. Major epicardial coronary arteries were isolated from the hearts and routinely processed for histopathological study. We evaluated the presence of coronary atherosclerosis and thrombosis. Plaque size was histologically graded with low magnification lenses.
Results: Coronary atherosclerosis, which was found in 110 hearts, caused critical stenosis or occlusion of at least one major vessel in 55 (41.6%) cases. Coronary thrombosis was found in 10 vessels from nine different hearts. One coronary tree presented two thrombi in two different vessels. Thrombi were mural in all but one vessel. We did not observe either deep sub-thrombotic ulceration or atheromatous material mixed with thrombus. Deep thrombus layers often presented organizing features. There was no correlation between thrombosis and degree of vessel stenosis, which was only mildly increased by thrombus. Plaque rupture without thrombus was found in five coronary arteries of five different cases.
Conclusions: Coronary thrombus may overlay the intima of a diseased vessel independently of plaque type and severity. Moreover, thrombosis is more frequent than expected, although it is rare when compared with the spread of coronary atherosclerosis. It may represent a plaque progression mechanism in the natural history of coronary atherosclerosis.