The spatial QRS-T angle in the Frank vectorcardiogram: accuracy of estimates derived from the 12-lead electrocardiogram

Schreurs, Charlotte A.; Algra, Annemijn M.; Man, Sum-Che; Cannegieter, Suzanne C.; van der Wall, Ernst E.; Schalij, Martin J.; Kors, Jan A.; Swenne, Cees A.

doi:10.1016/j.jelectrocard.2010.03.009

« Previous Next »Journal of Electrocardiology
Volume 43, Issue 4 , Pages 294-301, July 2010

The spatial QRS-T angle in the Frank vectorcardiogram: accuracy of estimates derived from the 12-lead electrocardiogram

Charlotte A. Schreurs, BSc
- Department of Cardiology, Leiden University Medical Center, The Netherlands
- Shared first authorship.
Annemijn M. Algra, BSc
- Department of Cardiology, Leiden University Medical Center, The Netherlands
- Shared first authorship.
Sum-Che Man, MD
- Department of Cardiology, Leiden University Medical Center, The Netherlands
Suzanne C. Cannegieter, MD
- Department of Clinical Epidemology, Leiden University Medical Center, The Netherlands
Ernst E. van der Wall, MD
- Department of Cardiology, Leiden University Medical Center, The Netherlands
Martin J. Schalij, MD
- Department of Cardiology, Leiden University Medical Center, The Netherlands
Jan A. Kors, PhD
- Department of Medical Informatics, Erasmus Medical Center Rotterdam, The Netherlands
Cees A. Swenne, PhD
- Department of Cardiology, Leiden University Medical Center, The Netherlands
- Corresponding author. Department of Cardiology, C5-P Leiden University Medical Center, PO Box 9600, 2300 RC Leiden, The Netherlands.

Received 29 January 2010 published online 26 April 2010.

Abstract

Background and Purpose

The spatial QRS-T angle (SA), a predictor of sudden cardiac death, is a vectorcardiographic variable. Gold standard vertorcardiograms (VCGs) are recorded by using the Frank electrode positions. However, with the commonly available 12-lead ECG, VCGs must be synthesized by matrix multiplication (inverse Dower matrix/Kors matrix). Alternatively, Rautaharju proposed a method to calculate SA directly from the 12-lead ECG. Neither spatial angles computed by using the inverse Dower matrix (SA-D) nor by using the Kors matrix (SA-K) or by using Rautaharju's method (SA-R) have been validated with regard to the spatial angles as directly measured in the Frank VCG (SA-F). Our present study aimed to perform this essential validation.

Methods

We analyzed SAs in 1220 simultaneously recorded 12-lead ECGs and VCGs, in all data, in SA-F-based tertiles, and after stratification according to pathology or sex.

Results

Linear regression of SA-K, SA-D, and SA-R on SA-F yielded offsets of 0.01°, 20.3°, and 28.3° and slopes of 0.96, 0.86, and 0.79, respectively. The bias of SA-K with respect to SA-F (mean ± SD, −3.2° ± 13.9°) was significantly (P < .001) smaller than the bias of both SA-D and SA-R with respect to SA-F (8.0° ± 18.6° and 9.8° ± 24.6°, respectively); tertile analysis showed a much more homogeneous behavior of the bias in SA-K than of both the bias in SA-D and in SA-R. In pathologic ECGs, there was no significant bias in SA-K; bias in men and women did not differ.

Conclusion

SA-K resembled SA-F best. In general, when there is no specific reason either to synthesize VCGs with the inverse Dower matrix or to calculate the spatial QRS-T angle with Rautaharju's method, it seems prudent to use the Kors matrix.