For some time a transitory insufficiency of the coronary blood flow has been accepted as the physiologic basis for the anginal syndrome. Only recently,1 however, has it been sufficiently realized in this country that infarction of the myocardium may result from acute coronary insufficiency, in the absence of coronary occlusion or even of coronary sclerosis. The German literature2 has emphasized the frequency of cardiac infarction due to coronary insufficiency. In two large series of cases of myocardial infarction studied post mortem, Graef3 and Horn4 found recent coronary occlusion in only 60 per cent, the remaining infarcts being associated with coronary insufficiency. Several authors5 have stated that in sudden death due to disease of the coronary arteries an acute occlusion frequently is not found.
These two types of infarction differ sharply in their pathogenesis and in the pathologic changes they present. Occlusion of a coronary artery