R.E.B.E.L. ECG of the Week #5

04 Dec
December 4, 2013

R.E.B.E.L. EM ECG of the Week #555 year old male with chief complaint of palpitations.  Denies any chest pain, shortness of breath, diaphoresis, or syncope.  His past medical history is significant for diastolic congestive heart failure, type 2 diabetes mellitus, hypertension, and hyperlipidemia. Per patient he had a diagnosis of atrial fibrillation vs ventricular tachycardia 2 years prior, but he is unsure of which one exactly.

BP: 153/83     HR: 183     RR: 18     O2 on RA: 99%     Temp: 36.3

ECG from triage is shown…

Before reading on, try to come up with your own interpretation of this ECG before moving on to the final impression

Ventricular Tachycardia

  • Rate: Ventricular rate 180
  • Rhythm: A-V Dissociation
  • Axis: Extreme Axis
  • QRS: Wide Complex (Consistent with VT)
  • Final ECG Interpretation: Wide Complex Tachycardia consistent with VT

When confronted with a 12-lead ECG that shows wide complex tachycardia (WCT), is a correct diagnosis vital for acute treatment, prognosis, and even subsequent work-up? The vast majority of WCT is due to ventricular tachycardia (VT) or supraventricular tachycardia with aberrancy (SVT-A). It is taught that the ECG remains the cornerstone for diagnosis of VT vs SVT-A, and there are several criterion that can be used to help in differentiating WCT. Obviously, a physician cannot memorize all of the algorithms, so if you were to pick one, which would it be? or should you even bother picking one?

What are the criteria used for differentiation of VT vs SVT-A?

What are the original article sensitivities, specificities, and accuracies of the above algorithms? (22333239)

AlgorithmSensitivity (%)Specificity (%)Accuracy (%)
Brugada Algorithm98.796.5---
Vereckei (aVR) Algorithm96.075.095.5
R-Wave Peak Time (RWPT) in Lead II93.099.0---
Griffith (Bundle Branch Block) Algorithm64.096.0---
Bayesian Algorithm97.056.0---
Sasaki Rule (NOT VALIDATED YET)86.097.086.0

What are the subsequent sensitivities, specificities, and accuracies of the above algorithms? (22333239)

AlgorithmSensitivity (%)Specificity (%)Accuracy (%)
Brugada Algorithm89.059.277.5
Vereckei aVR Algorithm87.148.071.9
R-Wave Peak Time (RWPT) in Lead II60.082.768.8
Griffith (Bundle Branch Block) Algorithm94.239.873.1
Bayesian Algorithm89.052.074.7

Case Conclusion: Pt was given 150mg of amiodarone and converted to NSR within 1 minute of receiving this medication (Shown below).

Normal Sinus Rhythm

Patient ended up having an extensive workup including:

  1. Heart catheterization: Minimal coronary artery disease with a 70 – 80% occlusion of a distal obtuse marginal vessel
  2. Cardiac biopsy: No pathology consistent with amyloidosis, sarcoidosis, or myocarditis
  3. EP Study: LVOT Tachycardia secondary to aorto-mitral valve continuity
  4. Final Dx: LVOT Tachycardia

Take Home Points

  • In unstable patients, JUST USE ELECTRICITY. Synchronized cardioversion works no matter what the diagnosis is.
  • Most of the algorithms are not as sensitive, specific, or accurate as their original studies
  • All algorithms have only moderate accuracy and should NOT be used in determining Vtach vs SVT with aberrancy, just assume Vtach!!

Bibliography

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Salim Rezaie

Emergency Physician at Greater San Antonio Emergency Physicians (GSEP)
Creator & Founder of R.E.B.E.L. EM
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2 replies
  1. Ken Grauer, MD says:

    Important post by Salim about an always important topic. Reasons why the regular WCT at ~170/minute shown here is VT with >99% certainty include the following: i) Extreme axis deviation (QRS all negative in lead I); ii) very wide and amorphous (ie, “ugly”) QRS; and iii) Global positivity in all precordial leads.

    The tracing is small in size – but I admit that I don’t see AV dissociation. One often can’t make out AV dissociation with certainty for VT rhythms that are relatively rapid. I do see notching in the middle of the R-R interval in several leads that looks to have a 1:1 retrograde (V:A) relationship – but as best I can tell, distance of this notch to the preceding QRS is constant.

    I agree that there are MANY systems proposed for distinguishing VT from SVT with preexisting bundle branch block or aberration. I’d like to propose my own, that admittedly is not validated as a separate system – but rather reflects criteria described by others. I call it, “The 3 Simple Rules”. In my experience (admittedly anecdotal) – these rules are easy to remember – can be applied in seconds – and are highly accurate in a majority of cases. Full details at THIS LINK: https://www.kg-ekgpress.com/acls_comments-_issue_11/#3%20SIMPLE%20RULES%20-%20Main%20HEADING

    Thanks again Salim for this post!

    Reply
    • Salim Rezaie says:

      Hello Ken,
      TY again for your thoughts, wisdom, and algorithm for SVT-A vs VT. Feel free to always put links to these ECG pearls. I appreciate you coming on and reading. Agree with everything that you have stated.

      Salim

      Reply

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