945-67 Diagnostic Significance of Exercise-induced ST-Segment Depression in the Lateral Limb Leads

Abstract

To evaluate the diagnostic significance of ST-segment depression in the lateral limb leads (I and aVL), 366 consecutive patients suspected of having CAD underwent standard exercise testing. They were aged 34 to 85 years; 234 were men and 132 women. No patient had previous myocardial infarction. A significant ST-segment depression of ≥ 0.1 mV were observed in the lateral limb leads in 57 patients (16%). In patients with ischemic ST-segment depression, those with the lateral limb lead ST-segment depression had a shorter duration of exercise (3.7 ± 1.6 vs 4.7 ± 1.8 min; p < 0.001), a slower peak heart rate (111 ± 20vs 125 ± 20 beats/min; p < 0.001), a greater magnitude of the maximal ST-segment depression (0.29 ± 0.14 vs 0.16 ± 0.08 mV; p < 0.001), and a greater number of leads with ischemic ST-segment depression (6.6 ± 1.6 vs 3.6 ± 1.8; p < 0.001) than those without. Sensitivities to detect significant CAD were lower by the lateral limb lead ST-segment depression than by the anterior or inferior lead ST-segment depression (23 vs 75, 53%; p < 0.0001 for both). In detecting multi-vessel CAD, however, the lateral limb lead ST-segment depression had a higher specificity and a positive predictive value than the anterior (92 vs 54%; P < 0.0001 and 67 vs 47%; P < 0.01, respectively), or the inferior lead ST-segment depression (92 vs 68%; p < 0.0001 and 67 vs 50%; p = 0.03, respectively). In particular, a positive predictive value in detecting multi-vessel CAD was 82% in 44 patients with ST-segment depression in both lateral limb and inferior leads. The lateral limb leads may be the last to develop ST-segment depression during exercise testing, which is regarded as a specific marker for severe coronary artery disease.