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 va lues) from body surface potential maps (BSPM), 12-lead electrocardiogr ams (ECGs), and Frank lead vectorcardiograms (VCGs) in diagnosing a pr ior inferior myocardial infarction (MI) in simulated left bundle branc h block (LBBB). The study included 32 patients whose digitized ECGs we re recorded simultaneously for BSPM, ECGs, and VCGs during normal sinu s rhythm and during right ventricular pacing simulating LBBB (1 8 with and 14 without an inferior MI). QRST values were calculated in each l ead point of ECGs. Data on 608 normal subjects were used as controls; mean +/- 2 SD was regarded as the normal range. The following paramete rs were derived: SIGMADM, SIGMADE, SIGMADV, the sum of the differences between the normal mean QRST value, and the QRST value of a given pat ient in leads where the QRST value was less than the normal range (''- 2 SD area'') in BSPM, ECGs, and VCGs (Y lead). The correlation coeffic ients for SIGMADM, SIGMADE, and SIGMADV between the two activation seq uences were highly significant. Sensitivity and specificity were as fo llows: 89% and 93% for SIGMADM >100 mV.ms, 89% and 93% for SIGMADE > 5 0 mV.ms, and 56% and 100% for SIGMADV >10 mV.ms, respectively. Althoug h SIGMADM, SIGMADE, and SIGMADV were significantly (P < .01) correlate d with the asynergy index calculated from left ventriculograms, SIGMAD M showed the best correlation. QRST values from BSPM, ECGs, and VCGs p rovide information that is useful in detecting an inferior MI and in e stimating the severity of left ventricular wall motion abnormalities i n the setting of LBBB. Of the three parameters, BSPM showed the best c orrelation with the severity of left ventricular wall motion abnormali ties.