Determinants of Exercise-Induced ST-Segment Displacement in the aV_L Lead in Patients With Known or Suspected Coronary Artery Disease

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Although the aV_L lead in exercise electrocardiography is reported to be helpful in identifying a significant narrowing of the left anterior descending coronary artery (LAD), its role in exercise testing has not been fully evaluated. Accordingly, 821 patients who underwent both standard exercise testing and coronary angiography were evaluated. In patients with aV_L lead ST elevation, the incidence of a significant narrowing of the LAD (124/165 vs 348/656; p<0.001) was higher than in those without. Multiple logistic regression analysis revealed that the 2 most important variables that correlated with aV_L lead ST elevation were a greater number of leads with ST depression in the inferior leads and a smaller amplitude of R wave in the aV_L lead. In contrast, variables correlating with aV_L lead ST depression in the majority of cases were a greater number of leads with ST depression in all leads and the presence of inferior lead ST elevation. The results of this study indicate that although aV_L lead ST elevation could be a marker for LAD narrowing, more important factors such as inferior lead ST-segment depression and the R-wave amplitude of the aV_L lead should be taken into consideration. In contrast, ST depression in the aV_L lead mostly represents exercise-induced myocardial ischemia of greater extent and severity. (Jpn Circ J 1999; 63: 104 - 110)