Objective To explore the infarct sites in patients with inferior wall acute myocardial infarction（AMI） concomitant with ST segment elevation in leads V1-V3 and leads V3R-V5R.Methods Five patients diagnosed as inferior

right ventricular

and anteroseptal walls AMI at admission were enrolled.Electrocardiographic data and results of isotope 99mTc-methoxyisobutylisonitrile（MIBI） myocardial perfusion imaging and coronary angiography（CAG） were analyzed.Results Electrocardiogram showed that ST segment significantly elevated in standard leads II

III

aVF

and leads V1-V3

V3R-V5R in all five patients.The magnitude of ST segment elevation was maximal in lead V1 and decreased gradually from lead V1 to V3 and from lead V1 to V3R-V5R.There was isotope 99mTc-MIBI myocardial perfusion imaging defect in inferior and basal inferior-septal walls.CAG showed that right coronary artery was infarct-related artery.Conclusions The diagnostic criteria for basal inferior-septal wall AMI can be formulated as follows:（1） ST segment elevates≥2 mm in lead V1 in the clinical setting of inferior wall AMI;（2） the magnitude of ST segment elevation is the tallest in lead V1 and decreases gradually from lead V1 to V3 and from lead V1 to V3R-V5R.With two conditions above

the basal inferior-septal wall AMI should be diagnosed.