What are the ECG discrimination criteria for ventricular tachycardia (VT)?

Updated: Dec 05, 2017
  • Author: Steven J Compton, MD, FACC, FACP, FHRS; Chief Editor: Jeffrey N Rottman, MD  more...
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Answer

Unfortunately, most VT tracings do not show obvious clues of AV dissociation, fusion, or capture. In such cases, the QRS morphology may often (depending on the clinical context) provide enough information to permit an accurate diagnosis. The two most commonly applied sets of ECG criteria are described below.

Brugada et al proposed ECG discrimination criteria for VT that focused primarily on the QRS morphologies in the precordial leads (V1-V6). [15]  They reported a sensitivity of 98.7% and a specificity of 96.5% with the following criteria:

  • Absence of RS complexes in the precordial leads
  • RS duration exceeding 100 ms in any precordial lead
  • Ventriculoatrial dissociation in any of 12 leads
  • Certain QRS morphologies, such as QR or QS in lead V6

Vereckei et al refined a different ECG algorithm based on a single lead, aVR, and reported better accuracy than was achieved with the Brugada criteria. [16]  They noted the presence of a negative QRS complex in lead aVR during right or left bundle-branch conduction of SVTs. VT was predicted by the following:

  • Presence of an initial R wave in lead aVR
  • Width of an initial R or Q wave exceeding 40 ms in lead aVR
  • Notching on the initial downstroke of a predominantly negative QRS complex in lead aVR
  • A ventricular activation-velocity ratio (V i/V t) of 1 or less

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