Syncope makes up approximately 1% of acute care visits in Canadian emergency departments and is a common symptom for a wide range of underlying etiologies.1 Identifying any serious underlying condition for syncope and disposition planning is the main area of focus in the emergency department. In addition to a comprehensive history and physical, the 12-lead ECG is a part of the initial evaluation in any patient presenting with syncope.
The mnemonic, WOBBLER can be used as a memory aid for pertinent ECG findings for patients with syncope aside from obvious ischemic changes or dysrhythmias.
W – Wolff-Parkinson-White Syndrome
Delta wave with PR shortening and QRS widening2
O – Obstruction
Obstruction of AV node (e.g. Mobitz type II, third degree heart block) or obstructive causes (pulmonary embolism, cardiac tamponade)
B – Brugada Syndrome
Brugada – Type 1 (Coved ST segment elevation in anterior precordial leads)3
B – Bifasicular block
Right bundle branch block + Left anterior fasicular block/left posterior fasicular block4
L – Left ventricular hypertrophy
Hypertrophic obstructive cardiomyopathy (HOCM), aortic stenosis. Eg. Voltage criteria for LVH and q-waves found in HOCM5
E – Epsilon
Epsilon wave: arrhythmogenic right ventricular dysplasia. Positive blip found at the end of the QRS complex, best seen in V1-V26
R – Repolarization
Long QTc (>500 ms) or short QTc (<350 ms). To rule out long QTc, a useful rule of thumb is that a normal QTc is less than half the R-R interval.
- 1.Primary Writing Committee., Sandhu R, Raj S, et al. Canadian Cardiovascular Society Clinical Practice Update on the Assessment and Management of Syncope. Can J Cardiol. 2020;36(8):1167-1177. doi:10.1016/j.cjca.2019.12.023
- 2.Delta Wave. Life in the Fast Lane. https://litfl.com/wp-content/uploads/2018/08/ECG-Delta-wave-3.png
- 3.Brugada Syndrome . Life in the Fast Lane. https://litfl.com/wp-content/uploads/2018/08/ECG-Brugada-Syndrome-Type-1-2.jpg
- 4.Bifascicular Block. Life in the Fast Lane. https://litfl.com/wp-content/uploads/2018/08/ECG-Bifascicular-Block-RBBB-LAFB.jpg
- 5.Dagger Q Waves. Life in the Fast Lane. https://litfl.com/wp-content/uploads/2018/08/ECG-HCM-Dagger-Q-waves-.jpg
- 6.Epsilon Wave. Life in the Fast Lane . https://litfl.com/wp-content/uploads/2018/08/ARVD-Epsilon_wave-590×155.jpg
Reviewing with the Staff #1
Life-threatening causes of syncope are primarily cardiac in nature, and thus the ECG becomes a great screening tool for these causes. We must be as good at searching ECGs for dangerous causes of syncope as we are at spotting STEMIs.
The WOBBLER mnemonic, in this case, provides the ED practitioner with a very useful memory aid to search for the other causes of syncope that don’t necessarily “jump out” of the ECG, as do the obvious commonly-seen dysrhythmias.
Reviewing with the Staff #2
When reading EKGs for patients who present with syncope, it is important to remember that some findings in this list can be transient and may not show up on the EKG in the ED. One prominent example is Brugada syndrome. The key in these patients is in the history. Syncope that happens without a prodrome, that results in significant facial trauma, or happens in the context of exertion are key features that warrant cardiology consultation, regardless of the EKG findings.