Case: A 57 yo patient with PMHx of CAD and HTN presents with a regular wide-complex tachycardia, HR 150 but otherwise vitals signs stable. You vaguely remember that there are various algorithms to distinguish VTach from SVT + aberrancy, and wonder if you can potentially give them adenosine and save them an admission.
This week we’re talking about wide-complex tachycardias. There are a number of methods to attempt distinguishing a wide SVT from ventricular tachycardia, and this paper compares their clinical utility.
Article: Jastrzebski M, Kukla P, Czarnecka D, Kawecka-Jaszcz K. Comparison of five electrocardiographic methods for differentiation of wide QRS-complex tachycardias. Europace. 2012 Aug;14(8):1165-71. doi: 10.1093/europace/eus015. Epub 2012 Feb 14. PMID: 22333239.
What: A retrospective study in which five different criteria of diagnosing ventricular tachycardia were applied to 260 ECGs with Wide-Complex Tachycardia (WCTs), defined as a rhythm of 100-250 bpm with a QRS>120 ms and confirmed by electrophysiologic studies. This included the Brugada, Griffith, Bayesian, Lead aVR, and Lead II RWPT methods. Two cardiologists, one general and one electrophysiologist with an EM resident, IM resident and a cardiology fellow looked through the 260 ECGs and applied the criteria to the ECG. Afterwards, this was compared to the definitive final diagnosis made by electrophysiology studies, calculating the sensitivity/specificity and accuracy of each algorithm.
Why: The results showed that accuracy (percentage of correct diagnosis) for all five algorithms ranged from 68.8% to 77.5%. Sensitivities also show a similar range with the Griffith method showing the highest sensitivity of diagnosing SVT at 94.2%. Notably, this study did not reproduce the SN/SP initially reported in the original studies, showing significantly lower sensitivity and specify. This paper was remarkable because it was at the first “head-to-head” comparison of the various ECG algorithms used to differentiate VTach from SVT with aberrancy.
In the ED, how can we readily differentiate between a true ventricular tachycardia and an SVT with aberrancy? Based on this paper and other articles, there is no algorithm that can give you a certain answer. Even the “best” algorithm utilized by cardiologists can misdiagnose a wide-complex tachycardia and lead us astray, with potentially devastating consequences (for example, using a CBB in a patient with VTach). Furthermore, most studies investigating the application of these ECG algorithms utilized cardiologists or electrophysiologists, rather than emergency physicians. Even if one is exceptionally sharp with ECGs, it may be more difficult to apply nuanced criteria in the midst of a busy ED shift.
Dr. Amal Mattu in ECGWeekly often warns of the dangers of assuming that a wide-complex rhythm is an SVT. Even the response to Adenosine does NOT rule out ventricular tachycardia.(1) And this study highlights how any current algorithm is far from perfect.
Bottom-line: There is no perfect method to differentiate a wide-complex SVT from Ventricular tachycardia. If there is any doubt, we should assume that a regular wide-complex tachycardia represents ventricular tachycardia and act accordingly.
As always, read for yourself and discuss with your attending/colleagues and local cardiologist.
Written by:
Dr. Jorge Aceves
Chief Resident
Cook County Health
Twitter: @joaceve91
Reviewed by:
Dr. Neeraj Chhabra
Attending Physician
Cook County Health
Twitter: @NeerajBC