The Value of Lead aVR ST Segment Changes in Localizing Culprit Lesion in Acute Inferior Myocardial Infarction and Its Prognostic Impact

BACKGROUND: Identifying infarct-related artery (IRA) in patients with inferior ST elevation myocardial infarction (STEMI) has prognostic and therapeutic benefits. OBJECTIVES: To differentiate IRA and the location of culprit lesion in inferior STEMI, using ST segment changes in lead aVR. METHODS: ST segment changes in lead aVR were recorded in 150 patients, admitted with first inferior STEMI. The association of IRA and the location of culprit lesion with ST segment changes in aVR were investigated. RESULTS: ST elevation ≥ 0.5 mm in lead aVR was present in 17 patients (11.3%), ST depression ≥ 0.5 mm in 74 patients (49.3%) and 59 patients (39.3%) did not have significant ST segment changes. Right coronary artery (RCA) was the IRA in 117 patients (78%) and left circumflex artery (LCX) in 33 patients (22%). Prevalence of RCA involvement as the IRA was different in three study groups (94.1% in ST elevation group, 83.1% in isoelectric group and 70.3% in ST depression group, P = 0.049). Presence of ST elevation had a sensitivity and specificity of 13.68 % and 96.97%, for detecting RCA lesions, respectively. ST depression had 66.67% sensitivity and 55.56% specificity for identifying LCX lesions. Clinical complications were low in our study with no significant difference among patients of three groups. CONCLUSIONS: Presence of ST elevation is highly suggestive of RCA lesions versus LCX lesions, whereas absence of ST elevation cannot rule out RCA lesions. Presence of ST depression has a moderate sensitivity and specificity for LCX lesions.