Different types of disorders, varying in time, concerning atrio-ventricular (AV) conductivity may occur during myocardial infarction (MI). Similarly, angiography may reveal the dynamics within lesions of thrombosis in arteries. A case of 58 year-old man, who suffered from temporal AV block of all degrees, and what is more, a block in anterior fascicle or the whole left bundle branch in the bundle of His is presented. Only the second coronary arteriography revealed a thrombosis in coronary artery. Successful angioplasty resulted in relief of symptoms and conductivity disorders. Clinical course of MI was discussed on the basis of the described case.