ST Segment Depression in Lateral Leads in Inferior Wall Acute Myocardial Infarction

BACKGROUND: The electrocardiogram may provide valuable information regarding the identity of the culprit coronary artery and the location of obstructing lesion within the artery, which may be of guidance in selecting the therapeutic modality. Previous studies have concluded that changes in lateral leads (I, aVL, V5, V6) are predictive of left circumflex coronary artery obstruction in inferior wall acute myocardial infarction. Elect-rocardiographic criteria for determining the location of the obstructing lesion, however, have not been well established. The purpose of this study is to investigate the patterns of ST segment depression in lateral leads in inferior wall acute myocardial infarction and the obstruction site of culprit artery according to ST segment depression in lateral leads. METHODS: We examined 78 patients with inferior wall acute myocardial infarction analizing their electrocardiogram and coronary angiography which performed during acute hospitalization. RESULTS: Of the fifty-five patients in which the culprit artery could be determined, 1)in 41 the culprit artery was the right coronary artery (19 proximal to the right ventricular branch and 22 distal), and in 14 the left circumflex coronary artery (7 proximal to the first obtuse marginal branch or involving a high first obtuse marginal branch, and 7 with distal obstruction). 2)Significant ST depression (ST< or =1 mm) in leads I and aVL was more common in right coronary artery obstruction (p<0.05 and p=0.01 respectively) than left circumflex artery. 3)It was difficult to define the location of obstruction with ST segment change of lateral precordial leads (V5, V6). CONCLUSIONS: In acute inferior wall myocardial infarction, ST segment depression in lateral limb leads (I, aVL) can be indicative of the right coronary artery obstruction and the ST segment depression pattern in lateral precordial leads was not indicative of the site of obstruction.

Significance of three electrocardiographic indexes in predicting the myocardial infarct-related artery in inferior wall of acute myocardial infarction / 中国介入心脏病学杂志

Objective To investigate the significance of three electrocardiographic indexes in predicting the myocardial infarct related artery (IRA) in inferior wall of acute myocardial infarction (IAMI) Methods One hundred and twenty patients with IAMI were studied Results (1) IRA was related to right coronary artery (RCA) in 98 (81 7%) case, left circumflex branch (LCX) in 22 (18 3%) cases (2) ST segment depression in lead Ⅰ identified RCA occlusion with a sensitivity of 77 6%, specificity of 90 9% in patient with IAMI, but isoelectric or elevated ST segment in lead Ⅰ identified LCX occlusion with a sensitivity of 90 9%, specificity of 77 6% (3) About QRS wave of lead aVL, S/R≥1/3 identified RCA occlusion with a higher sensitivity of 93 9% and a lower specificity of 63 6% (4) When IRA was RCA, ST segment elevated amplitude Ⅲ≥Ⅱ identified as a diagnostic index no matter the location of occlusion Conclusion Three electrocardiographic indexes have significant value in predicting the infarct related artery in inferior wall acute myocardial infarction