THE RELATIONSHIP OF INFERIOR ST DEPRESSION, LATERAL ST ELEVATION, ANDLEFT PRECORDIAL ST ELEVATION TO MYOCARDIUM AT RISK IN ACUTE ANTERIOR MYOCARDIAL-INFARCTION

The purpose of this study was to examine the relationship between the presence or absence of ST segment depression in inferior leads (II, II I, and aV(F)) and ST segment elevation in lateral (I and aV(L)) or lef t precordial (V5 and V6) leads with the amount and location of myocard ium st risk for infarction in patients with acute anterior myocardial infarction. Forty-three patients with anterior infarctions were inject ed with technetium 99m-sestamibi when they were first seen and underwe nt tomographic imaging to measure the amount and location of myocardiu m at risk. Patients with inferior ST depression (n = 10) compared with those without ST depression (n = 33) had perfusion defects that exten ded significantly further into the lateral wall (47 degrees vs 20 degr ees, p = 0.04) and larger anterior injury vectors (6.47 vs 4.92, p = 0 .008). There was no significant association with the percentage of myo cardium at risk, disease of the right coronary artery, the presence of an inferior perfusion defect, or the size of the inferior injury vect or. Among the patients with ST elevation in lateral leads (n = 16) com pared with those without (n = 27), there was a significantly more late ral defect border (47 degrees vs 25 degrees, p = 0.007) and a larger a nterior injury vector (6.07 vs 4.81, p = 0.01). There was no significa nt correlation with the percentage of myocardium at risk. A significan t relationship could not be demonstrated between the presence of ST el evation in the left precordial leads and any measure of the amount or location of myocardium at risk. These data support the theory that inf erior ST depression in patients with transmural anterior ischemia is a ''reciprocal'' finding and does not represent inferior ischemia. The presence of inferior ST depression or lateral ST elevation is associat ed with a more lateral perfusion defect. Neither of these ECG findings is associated with the amount of myocardium at risk for infarction.