USEFULNESS OF CONTINUOUS ST MONITORING IN INFERIOR WALL ACUTE MYOCARDIAL-INFARCTION FOR DESCRIBING THE RELATION BETWEEN PRECORDIAL ST DEPRESSION AND INFERIOR ST ELEVATION

To explore the relation between precordial and inferior ST-segment cha nges within individual patients, continuous 12-lead electrocardiograph ic recording was performed in 19 patients with acute inferior infarcti on given intravenous thrombolytic therapy. Monitoring was performed fo r 519 +/- 269 minutes. The extent of inferior ST elevation varied cons iderably with time in all patients. With use of the maximal precordial ST depression recorded to classify patients, 11 had precordial ST dep ression (SIGMAV1-3) > 0.2 mV (group A) and 8 had less-than-or-equal-to 0.2 mV or no precordial ST depression (group B). The maximal recorded precordial ST depression correlated inversely with the corresponding inferior SF elevation in the 19 patients (r = -0.78, p < 0.001). Withi n individual patients, continuous 12-lead monitoring revealed a dose n egative correlation between the inferior and precordial ST levels for the entire recording period in many patients, but 5 of the 19 patients (26%) (2 in group A and 3 in group B) did not have this relation. Mor eover, precordial ST depression was not always present during inferior ST elevation in group A patients: 4 of 11 (36%) had some electrocardi ographs showing < 0.1 mV precordial ST depression despite summed infer ior ST elevation > 0.6 mV. These data indicate that precordial ST depr ession is not just the simple electrical reciprocal projection of the abnormal inferior wall ST vector, and its fluctuation cannot be predic ted by changes in inferior ST level in every patient . The reciprocal correlation between precordial and inferior ST levels in the whole gro up and within many individual patients over time may suggest that prec ordial ST depression reflects an area of ischemia adjacent to but anat omically distinct from the inferior wall which shares a common vascula r supply from the infarct -related artery.