The severity of ST segment elevation in acute inferior myocardial infarction: does it predict the presence of a proximal culprit lesion along the right coronary artery course?

OBJECTIVE: Acute inferior myocardial infarction (AIMI) is generally characterized by ST segment elevation in the limb leads (D2, D3, aVF). Many trials have reported the close relation between the severity of this ST segment elevation and the extent of infarction, and also the prognosis. Based on the clinical studies, several electrocardiographic (ECG) criteria have also been propounded to identify the infarct-related artery. This study was conducted to investigate the possible relation between the severity of ST segment elevation and the proximity of the culprit lesion along the right coronary artery (RCA) course in AIMI.

METHODS: Sixty patients (31 female, 29 male) admitted to our centre with diagnosis of first AIMI were included in the study. All cases underwent coronary angiography (CAG) on the 6th day of hospitalization. Patients with non-dominant RCAs were excluded from the study. The lesion with the highest degree of stenosis along the RCA course was accepted as the culprit lesion. The RCA was divided into 3 segments: proximal portion (from ostium to the first acute marginal (AM) artery), midportion (from the first AM to the last AM), distal portion (from the last AM on). In each case, a single value (STSE) was obtained by the addition of the amplitudes (mm) of ST segment elevation in the limb leads (D2, D3, aVF) during the hyperacute stage of AIMI.

RESULTS: The patients with the culprit lesions in the proximal portion of the RCA were found to have a mean STSE value of 12.61+/-3.79 mm, while the patients having the culprit lesions in the mid and distal portions were found to have mean STSE values of 6.88+/-1.20 mm and 5.05+/-0.97 mm, respectively. There was a significant positive correlation between the severity of ST segment elevation and the culprit lesion proximity (r=0.82, p<0.01 for the proximal and r=0.7, p<0.05 for the mid portions of RCA).

CONCLUSION: In AIMI, the severity of ST segment elevation and the proximity of the culprit lesion along the infarct-related RCA was found to be closely related, indicating the informative feature of ST segment elevation in the prediction of culprit lesion location.