Determination of the Site of Myocardial Infarction by QRST Isointegral Mapping in Patients with Abnormal Ventricular Activation Sequence

QRST isointegral maps were constructed from 87-lead ECGs in 37 patients with abnormal ventricular activation, such as ventricular premature beats, WPW syndrome, left bundle branch block and right bundle branch block. Patients were divided into 2 groups, the old myocardial infarction (OMI) group (n=18) and the non-infarction group (n=19). In the latter group, QRST isointegral maps showed smooth bipolar surface distributions, with positive values located over the precordium and negative values over the right upper anterior chest and the back, independent of the ventricular activation sequence. In the OMI group, for individual patients, the distribution patterns of QRST isointegral maps were similar between normal sinus rhythm and VPB or WPW conduction. Including the patients with BBB, a decrease of the time-integral value was consistently found in leads which corresponded to an asynergic site indicated by left ventriculography. To evaluate the abnormalities of QRST isointegral maps, particular attention was given to the area where the QRST time-integral value was less than the lower limit determined by 40 normal subjects; this area was designated as the negative departure area. Characteristic distribution patterns of the negative departure area seem to indicate the asynergic site, independent of the activation sequence. Thus, the QRST isointegral map may be useful for identifying the asynergic site in patients with abnormal ventricular activation sequence, that is hardly detected with conventional electrocardiograms.