高倍镜示心肌梗死大约1到2天。心肌纤维有暗红的收缩带经过，心肌细胞核几乎全部消失，有急性炎症的迹象，急性心肌梗死在临床上表现为心电图改变以及肌酸激酶同工酶升高。
This high power microscopic view of the myocardium demonstrates an infarction of about 1 to 2 days in duration. The myocardial fibers have dark red contraction bands extending across them. The myocardial cell nuclei have almost all disappeared. There is beginning acute inflammation. Clinically, such an acute myocardial infarction is marked by changes in the electrocardiogram and by a rise in the MB fraction of creatine kinase.