Fifty five anatomo-clinical cases of patients who died of a recent myocardial infarction were divided into two groups according to existence of a complete block of one of the branches of the bundle of His, which occured at the same time as the myocardial necrosis: group A: 14 cases comprising 13 complete right blocks and only one complete left block, or absence of intraventricular conduction disorders: group B: 41 cases. The macroscopic anatomical study separated the two groups: in group A there was a very high frequency of healed posterior infarction, extensive recent anterior infraction, transeptal through the anterior and upper half of the interventricular septum by occlusion of the anterior interventricular artery in its proximal segment, above the origin of the second anterior septal artery, associated to severe stenosing lesions of the other coronary trunks, in particular the right coronary artery.