INFEROSEPTAL MYOCARDIAL-INFARCTION - ANOTHER CAUSE OF PRECORDIAL ST-SEGMENT DEPRESSION IN TRANSMURAL INFERIOR WALL MYOCARDIAL-INFARCTION

ECG ST-segment depression in the anterior precordial leads is a frequent observation during the initial hospital phase of acute transmural inferior myocardial infarction (MI), but is of uncertain significance. No available clinical studies have examined the prevalence of inferoseptal necrosis complicating inferior MI. The clinical course, ECG features, radionuclide angiograms and cardiac enzyme changes in 57 patients with transmural inferior MI who did not have prior anterior or concomitant true posterior MI, associated anterior or posterolateral asynergy by radionuclide ventriculography, or left or right bundle branch block were reviewed retrospectively. Patients were categorized according to the presence (group A) or absence (group B) of precordial ST-segment depression and according to the presence (group I) or absence (group II) of radionuclide septal wall motion abnormalities. There were no significant differences in global left ventricular ejection fraction (group A, 49 .+-. 8, group B, 52 .+-. 41; group I, 51 .+-. 7, group II, 51 .+-. 6), right ventricular ejection fraction (group A, 45 .+-. 9, group B, 42 .+-. 7; group I, 43 .+-. 8, group II, 41 .+-. 8), or clinical outcome in the hospital. Chi-square analysis revealed a significant (P < 0.05) association between the presence or absence of septal asynergy and the presence or absence of precordial ST depression. Average peak creatine kinase elevation (group I, 761 .+-. 164 IU; group II, 698 .+-. 178 IU) attained marginal significance by paired t test (P = 0.06). Precordial ST-segment depression during transmural inferior MI is frequently associated with septal asynergy by gated radionuclide angiography (15 of 26 patients, 58%). Inferoseptal MI may be another explanation for the reciprocal precordial ST-segment depression observed in these patients.