COMPARATIVE-STUDY OF QRST VALUES FROM BODY-SURFACE POTENTIAL MAPPING, 12-LEAD ECGS, VCGS IN DETECTING INFERIOR MYOCARDIAL-INFARCTION, AND EVALUATING THE SEVERITY OF LEFT-VENTRICULAR WALL-MOTION ABNORMALITIES IN SIMULATED LEFT-BUNDLE-BRANCH BLOCK

The authors compared the ability of QRST time-integral values (QRST values) from body surface potential maps (BSPM), 12-lead electrocardiograms (ECGs), and Frank lead vectorcardiograms (VCGs) in diagnosing a prior inferior myocardial infarction (MI) in simulated left bundle branch block (LBBB). The study included 32 patients whose digitized ECGs were recorded simultaneously for BSPM, ECGs, and VCGs during normal sinus rhythm and during right ventricular pacing simulating LBBB (1 8 with and 14 without an inferior MI). QRST values were calculated in each lead point of ECGs. Data on 608 normal subjects were used as controls; mean +/- 2 SD was regarded as the normal range. The following parameters were derived: SIGMADM, SIGMADE, SIGMADV, the sum of the differences between the normal mean QRST value, and the QRST value of a given patient in leads where the QRST value was less than the normal range (''-2 SD area'') in BSPM, ECGs, and VCGs (Y lead). The correlation coefficients for SIGMADM, SIGMADE, and SIGMADV between the two activation sequences were highly significant. Sensitivity and specificity were as follows: 89% and 93% for SIGMADM >100 mV.ms, 89% and 93% for SIGMADE > 50 mV.ms, and 56% and 100% for SIGMADV >10 mV.ms, respectively. Although SIGMADM, SIGMADE, and SIGMADV were significantly (P < .01) correlated with the asynergy index calculated from left ventriculograms, SIGMADM showed the best correlation. QRST values from BSPM, ECGs, and VCGs provide information that is useful in detecting an inferior MI and in estimating the severity of left ventricular wall motion abnormalities in the setting of LBBB. Of the three parameters, BSPM showed the best correlation with the severity of left ventricular wall motion abnormalities.