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Value of the Signal-Averaged ECG in Supraventricular Tachycardia Diagnosis
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  • Romain CASSAGNEAU,
  • Allan Skanes,
  • Peter Leong-Sit,
  • Jaimie Manlucu,
  • Raymond Yee,
  • Lorne Gula,
  • Anthony Tang,
  • George Klein
Romain CASSAGNEAU
LONDON HEALTH SCIENCE CENTRE
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Allan Skanes
University Of Western Ontario
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Peter Leong-Sit
Western Univeristy
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Jaimie Manlucu
University of Western Ontario
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Raymond Yee
London Health Sciences Cntr-University Campus
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Lorne Gula
London Health Sciences Centre
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Anthony Tang
Island Medical Program, University of British Columbia, BC, Canada
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George Klein
University Hospital
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Abstract

Background: We hypothesized that signal averaged ECG during tachycardia would facilitate P wave recognition and assist in SVT diagnosis. P waves adjacent to the QRS during tachycardia would lengthen the filtered QRS and be recognized by subtracting QRS duration during sinus rhythm from that of tachycardia. Aims: to assess the feasibility of SaECG during SVT; to correlate the difference between the filtered QRS duration in SVT and sinus rhythm (ΔfQRSd) with the endocardial VA time; Methods & Results: Patients referred for an EP study and ablation of any SVT were included. A SAECG was acquired during SVT and compared with another during SR. 40 patients were included, 20 had AVNRT and 20 AVRT. For AVNRT, the P wave was detected as a pseudo-late potential in 16 patients. In 4 patients, P wave was invisible and presumed within the confines of the QRS. The mean ΔfQRSd was 2017 ms and the VA time was 1415 ms. For AVRT a distinct P wave separated from the QRS was detected in all patients. The ΔfQRSd was 10742ms and the VA time was 9631 ms. ΔfQRSd was longer during AVRT than AVNRT (p<0.0001). Over all, the ΔfQRSd correlated with the longest VA time (R=0.796). Motion artifact and sensing of T waves during tachycardia were 2 confounders. Conclusion: SaECG provides a rapid adjunct to the 12 lead ECG and is capable of identifying P waves and facilitating diagnosis of SVT mechanism.