We intended to assess the characteristics of ST segment deviation in lateral leads(aVL, I, V5, V6) in patients with acute inferior myocardial infarction(AIMI) and find out the relationship with culprit arteries.

The subjects were 51 patients diagnosed as AIMI by standard electrocardiogram, cardiac enzymes and typical chest pain. Subjects were devided into two groups by angiographically proven culprit arteries ; left circumflex artery(LCx) group and right coronary artery(RCA) group. We compared the frequencies of ST segment depression more than 1 mm and less than 1 mm in aVL and I, and ST segment elevation more than 0.5 mm and less than 0.5 mm in V5 and V6 in each culprit artery group.

Among 51 patients with AIMI, 42 were RCA group and 9 were LCx group. The frequency of ST segment depression more than 1 mm in aVL was 44% in LCx group and 71% in RCA group(p=0.140). 11% of LCx group and 43% of RCA group showed more than 1 mm ST segment depression in lead I (p=0.128). 56% of LCx group showed more than 0.5 mm ST segment elevation in V5 and V6 and 81% of RCA group showed less than 0.5 mm ST segment elevation in V5 and V6 (p=0.036).

Culprit arteries in patients with AIMI and ST segment deviation in V5 and V6 are significantly related with each other. ST segment elevation more than 0.5 mm in V5 and V6 was predominantly found in LCx group than RCA group. Observation for ST segment deviation in lateral precordial lead V5 and V6 would be important in predicting the culprit artery in AIMI.