RWPT-VT-2There are several algorithms that are currently used to help distinguish Supraventricular Tachycardia (SVT) with aberrancy and Ventricular Tachycardia (VT). Many of these algorithms lack specificity, and let’s face it, who can remember if the absence of an RS complex in the precordial leads is VT or SVT with aberrancy. So what if there was a criterion that had a good sensitivity (SN), specificity (SP), and was one simple step?

 What are some of the algorithms used to differentiate SVT with aberrancy and VT?

  • Brugada Algorithm (Most commonly used): SN 89%, SP 59.2%1 (ALiEM post, PV card)
  • Vereckei aVR Algorighm: SN 87.1%, SP 48% 2 (PV card)
  • Bayesian Algorithm: SN 89%, SP 52% 3
  • Griffith (Bundle Branch Block) Algorithm: SN 94.2%, SP 39.8% 4

 What is the R-Wave Peak Time (RWPT) in lead II?

  • Duration from the QRS depolarization onset until the first change of polarity (independent of whether the QRS deflection is positive or negative) as measured in lead II
  • Another way to think of this is, duration from the isoelectric line to its first deflection

619px-RWPT 2

Image from ECGPedia.org

Why is lead II used and not other leads?

  • Almost always present on ECG rhythm strips recorded in different settings

How good is RWPT in lead II at differentiating between SVT with aberrancy and VT? 5

  • In a retrospective study of 218 wide complex tachycardia ECGs, RWPT ≥ 50 msec had a positive LR of 51.3
TestValue
 Sensitivity 93.2%
 Specificity 99.3%
 Positive Predictive Value 98.2%
 Negative Predictive Value 93.3%
  • A 2013 study (n=69) showed lower sensitivity numbers for the RWPT ≥ 50 msec criterion – SN 67% and SP 97% 6

Is RWPT ≥ 50 msec more accurate than QRS width ≥ 130 msec in lead II for differentiation of wide complex tachycardia? 5

  • Yes
  • QRS width ≥ 130 msec in lead II: SN 83.33% and SP 58.97%

If this criterion is so sensitive, specific, and easy to use, why don’t we use it instead?

  • There is some difficulty in defining the initiation and peak of ventricular complexes
  • Further prospective studies need to validate this rule

Conclusion

RWPT ≥ 50 msec in lead II seems to be simple, reproducible, and highly sensitive and specific for VT, but more prospective studies need to be performed to validate this rule.

 

1.
Brugada P, Brugada J, Mont L, Smeets J, Andries E. A new approach to the differential diagnosis of a regular tachycardia with a wide QRS complex. Circulation. 1991;83(5):1649-1659. [PubMed]
2.
Vereckei A, Duray G, Szénási G, Altemose G, Miller J. Application of a new algorithm in the differential diagnosis of wide QRS complex tachycardia. Eur Heart J. 2007;28(5):589-600. [PubMed]
3.
Lau E, Pathamanathan R, Ng G, Cooper J, Skehan J, Griffith M. The Bayesian approach improves the electrocardiographic diagnosis of broad complex tachycardia. Pacing Clin Electrophysiol. 2000;23(10 Pt 1):1519-1526. [PubMed]
4.
Griffith M, Garratt C, Mounsey P, Camm A. Ventricular tachycardia as default diagnosis in broad complex tachycardia. Lancet. 1994;343(8894):386-388. [PubMed]
5.
Pava L, Perafán P, Badiel M, et al. R-wave peak time at DII: a new criterion for differentiating between wide complex QRS tachycardias. Heart Rhythm. 2010;7(7):922-926. [PubMed]
6.
Datino T, Almendral J, Avila P, et al. Specificity of electrocardiographic criteria for the differential diagnosis of wide QRS complex tachycardia in patients with intraventricular conduction defect. Heart Rhythm. 2013;10(9):1393-1401. [PubMed]
Salim Rezaie, MD

Salim Rezaie, MD

ALiEM Associate Editor Clinical Assistant Professor of EM and IM University of Texas Health Science Center at San Antonio Founder, Editor, Author of R.E.B.E.L. EM and REBEL Reviews
Salim Rezaie, MD

@srrezaie

EM/IM Doc; Founder of REBEL EM & REBEL Cast; Doing my Part to Cut Down on KT Time; Viva #FOAMed #FOAMcc (Tweets are opinion only)