Severity of residual stenosis of infarct-related lesion and left ventricular function after single-vessel anterior wall myocardial infarction: Implication of ST-segment elevation in lead aVL of the admission electrocardiograms

Background: The relationship between the severity of chronic-phase stenosis of infarct-related lesions (IRLs) and chronic left ventricular function in anterior acute myocardial infarctions (AMI) has not been adequately invest igated. Hypothesis: This study investigated whether ST elevation in lead a VL of ad mission electrocardiogram (ECG) would be a determinant factor of the relati onship between the severity of stenosis of the IRL and chronic left ventric ular function after anterior wall AMI. Methods: One month after AMI, the IRL was evaluated by coronary angiography in 98 patients with anterior AMI, and left ventricular ejection fraction ( LVEF) was determined using multigated radionuclide angiocardiography. Patie nts were classified according to the severity of the IRL: patients with 100 % occlusion (Group O), patients with 90 to 99% stenosis (Group H), and pati ents with less than or equal to 75% stenosis (Group L). Patients with ST el evation greater than or equal to 0.1 mV in the a VL lead on their admission ECG were included in the ST-elevation group, and those with ST elevation < 0.1 mV were included in the non-ST-elevation group. Results: The LVEF was greater in the non-ST-elevation group than in the ST- elevation group (p<0.0001), and the LVEF in a whole group as follows: Group L LVEF > Group H LVEF>Group O LVEF (p = 0.0160). Ln the ST-elevation, grou p, LVEF was higher in Group L than in the other groups (p = 0.0251). There were three independent predictors of a reduced LVEF: ST-elevation in a VL [ odds ratio (OR): 3.38, p = 0.0044], IRL stenosis greater than or equal to 9 0% (OR: 2.90, p = 0.0044), and the IRL occurring in the left anterior desce nding artery proximal to the first diagonal branch (OR: 6.31, p = 0.0024). Conclusion: Left ventricular function was preserved, regardless of the seve rity of residual stenosis, in patients without ST elevation in a VL if the IRL was not totally occluded. In patients with ST elevation in a VL, LVEF w as lower in patients with more severe stenosis, even if the IRL was patent.