Right-to-left T-wave discordance in acute myocardial infarction: A new electrocardiographic sign of apical and left lateral infarction

Abstract

IntroductionA new ECG method producing Precordial Bipolar Leads (PBL) enables a computerized subtraction of the electrical activity detected by the precordial V1 lead from that of the V6 electrode (V6-V1 PBL). This calculation can also be performed manually using measurements from standard simultaneous 12 lead ECG (SS12LECG) tracings. We compared the magnitude of T-waves generated by PBL V6-V1 (measured by computer) to the SS12LECG V6-V1 T-waves (measured on the tracing) to determine whether these measurements are equivalent. Although Lead I and Lead V6-V1 PBL examine almost the same right-to-left axis, we noted that Lead I and Lead V6-V1 PBL sometimes have opposite T-wave polarities. We investigated this observation further using a database containing control and patient data. Material and methodsRecords of 79 patients and 52 controls from the Physionet database were used to generate the V6-V1 PBL for comparison to manual calculations from the V1 and V6 unipolar T-wave measurements on the tracings. The accuracy of these measurements was validated against the computer measurements by correlation and paired t-tests. ResultsThe T-wave automated and manual measurements in patients were strongly correlated (0.9895), consistent with the premise that measurements from tracings are accurate. The V6-V1 T-wave calculation was positive in 48 of the 52 control subjects. Nearly half of the acute myocardial infarction (AMI) patients had discordant T-wave polarity between Lead I and V6-V1 PBL; ventriculography results on 24 of these patients identified 13 patients with apical and 11 with lateral wall motion abnormalities. ConclusionA discordant T-wave in Lead I and in the V6-V1 PBL is a potential diagnostic criterion for apical or left-lateral infarction.