Comparison of the spatial QRS-T angle derived from digital ECGs recorded using conventional electrode placement with that derived from Mason-Likar electrode position

Background: The spatial QRS-T angle is ideally derived from orthogonal leads. We compared the spatial QRS-T angle derived from orthogonal leads reconstructed from digital 12-lead ECGs and from digital Holier ECGs recorded with the Mason-Likar (M-L) electrode positions. Methods and results: Orthogonal leads were constructed by the inverse Dower method and used to calculate spatial QRS-T angle by (1) a vector method and (2) a net amplitude method, in 100 volunteers. Spatial QRS-T angles from standard and M-L ECGs differed significantly (57 degrees +/- 18 degrees vs 48 degrees +/- 20 degrees respectively using net amplitude method and 53 degrees +/- 28 degrees vs 48 degrees +/- 23 degrees respectively by vector method; p < 0.001). Difference in amplitudes in leads V4-V6 was also observed between Holter and standard ECGs, probably due to a difference in electrical potential at the central terminal. Conclusion: Mean spatial QRS-T angles derived from standard and M-L lead systems differed by 5 degrees-9 degrees. Though statistically significant, these differences may not be clinically significant. (C) 2016 Elsevier Inc. All rights reserved.