The arrhythmia from Hell! Everyone stresses about wide complex tachycardias(WCT). In the Cardiac Bootcamp Course we make it simple.
A recent article in JAMA Internal Medicine looked at the ECG features that differentiated VT from SVT.
In the course you learn my 120CRAM rule. Let’s see what this paper found.
Cerantola M et al. Diagnostic Approach to Wide Complex Tachycardia. JAMA Intern Med 2021 Sep 1;181(9):1231-1233
A few points of summary from this article. 90% of patients with a WCT and a history of myocardial infarction, will be in Ventricular Tachycardia(VT).
We know that about 80% of WCT is VT, so it is a safe assumption. But there are a few other things to take into account.
The ECG factors that were associated with VT included:
A. AV Dissociation, Capture and Fusion Beats
B. Positive QRS in aVR
C. QRS Concordance in the precodial leads
D. QRS duration > 160ms
E. A deflection in the initial portion of the QRS
Causes of WCT
There are really only a few causes of Wide Complex Tachycardia:
- VT
- Sinus + Bundle Branch Block
- SVT with Aberrancy
- Hyperkalaemia
- Na Channel Blocker
- Paced Rhythm
- Ischaemia
What’s my 120CRAM formula?
120: This is a critical number. The rate must be faster than 120bpm and wider than 120ms. However BEWARE, if the QRS is too wide always think of HYPERKALAEMIA.
C: Concordance
R: Dominant R wave in aVR
A: AV dissociation
M: Morphology which includes capture and fusion beats and an Rsr pattern in V1 and a QS in V6 ( refer to the section on Wide Complex Tachycardia in the Course)
Below is a slide from the course.
