Arteriosclerotic narrowing or obliteration of one or more coronary arteries is present in almost all instances of myocardial infarction, but no generally acceptable statement can be made on the incidence of arterial thrombosis in such hearts. Reports of the incidence of coronary-artery thrombosis in acutely infarcted hearts, varying from 21% to 85%, emphasize the technical difficulties in dissection, postmortem artefacts, and hazy criteria for the definition of arterial thrombus which have hampered investigators in arriving at true values.
In an attempt to resolve these difficulties, Ehrlich and Shinohara in the October issue of the Archives of Pathology1 describe the results from microscopic examination of serial blocks of previously unopened, fixed, and decalcified specimens of the entire extramural coronary arterial tree. Rigid criteria were observed in the microscopic differentiation of thrombi from clots; 67 hearts, 38 with acute infarcts and 29 controls without infarcts, were analyzed by these techniques. These