Electrocardiogram (ECG) illustration from a 47 year old man admitted to hospital when he did not pay attention to intermittent chest pain for 2 days. High-sensitivity troponin is positive. Coronary angiography revealed 99% subtotal occlusion of the middle segment of left anterior descending branch. The coronary artery lesions were mainly located in the middle of left anterior descending artery. The left ventricular free wall myocardium is supplied by the developed diagonal branch and left circumflex branch, which provides ischemic protection, so the ECG myocardial infarction pattern is not typical.