Objective To analyze the seemingly normal electrocardiogram（ECG） characteristics of precordial leads in patients with acute myocardial infarction and the ECG parameters of the infarct related artery（IRA）. Methods The upright T wave and QRS complex characteristics of precordial leads data were analyzed retrospectively in patients with acute myocardial infarction from Janurary 2018 to December 2019

whose ECG seemed normal and the diagnosis was identified by emergency coronary angiography. Results Ten patients were enrolled

whose IRA was left anterior descending artery（LAD） in 7 patients and left circumflex artery（LCX） in 3 patients. All ECG showed upright T wave in precordial leads and TV2/TV6ratio>1. Wellens syndrome type Ⅱ ECG characteristics were developed in patients with LAD occlusion. However

no significant changes were observed in patients with LCX occlusion post percutaneous coronary intervention. The RV3and RV2/SV2ratio in LCX group were higher than those in LAD group（p=0.03

p=0.02

respectively）. RV3≥0.7mV was found in 4 cases

including 3 patients with LCX occlusion（0.7mV in another case with LAD occlusion）. RV2/SV2≥0.7 was detected in 3 cases and

all IRA was LCX. Conclusions Attention should be paid to the T wave and the R wave amplitude in the precordial leads in patients with typical angina pectoris-like persistent chest discomfort

even whose series ECG appear normal

which is helpful for the early diagnosis and timely reperfusion treatment of acute myocardial infarction.