Myocardial infarction and the intrinsic calibre of coronary arteries.

Thrombotic occlusion of a coronary artery occurs in most cases of fatal myocardial infarction (Mitchell and Schwartz, 1963; Allison et al., 1963), and it has been suggested that thrombosis is most likely to occur where the lumen is small (Osborn, 1963). Although the size of arterial plaques and the relative narrowing that they produce have been extensively studied, the absolute size of the effective lumen must also depend on the intrinsic calibre of the artery in which the lesions occur. This variable has occasionally been considered inwork on animals (Tepperman and Pearlman, 1961; Stevenson et al., 1964), but in human disease it seems to have been ignored. We have therefore measured intrinsic coronary artery calibre at necropsy in a representative sample of persons without infarction, and have compared the findings with those in a series of patients with necropsy evidence of infarction.