ECG of the Week: ECG of the Week - 13th March 2017

Wednesday 15 March 2017

ECG of the Week - 13th March 2017 - Interpretation

This ECG is from a 50 yr old male who presented with 2 hours of central chest pain. He has a history of palpitations and is a smoker.

Click to enlarge

Rate:

72 bpm

Rhythm:

Regular
Sinus rhythm

Axis:

Normal

Intervals:

PR - Short (~100ms)
QRS - Prolonged (110-120ms)

Segments:

ST Elevation II, III, aVF, V5-6
ST Depression lead aVL

Additional:

Delta wave
Biphasic T wave V2-4
T Inversion lead aVL

Interpretation:

Wolff-Parkinson-White / Pre-excitation

Short pr
Delta wave
QRS Prolongation
Type 'A' Pattern / Left sided accessory pathway
Left posterior AP using Modified Arruda Algorthm

ST changes on single ECG could be secondary to pre-excitation vs ACS

What happened ?

This patient had no old ECG's for comparison and had never been given a diagnosis of pre-excitation before today. The nature and history of the chest pain was suspicious of myocardial ischaemia. The patient was pain-free following initial ED treatment and serial ECG's did not show dynamic changes. He had raised troponins, peak trop I 0.28 ug/L, and underwent angiography which showed:

LM: Normal
LAD: Mild - mod / mild disease
Cx: Normal
RCA: 70% mid stenosis --> PCI with BMS

Post stent echo showed:

Normal LV size and function
Basal posterior wall motion abnormality due to pre-excitation
Normal RV size and function

The patient was commenced on DAPT, statin and beta-blocker therapy with planned electro-physiologist follow-up for EPS +/- ablation.

This case highlights the challenges of assessing for acute ischaemia in the setting of pre-excitation in this scenario clinical suspicion, serial ECG's and comparison with old ECG's are paramount. This are no 'rules' we can apply in these scenarios to differentiate acute ischaemia from the abnormalities seen due to pre-excitation.

A must read post

I'd encourage all our readers to look at this post from Dr Smith with some great examples of WPW with and without superimposed ischaemia:

http://hqmeded-ecg.blogspot.com.au/2014/07/repost-certain-pattern-of-pseudostemi.html

Accessory Pathway Location

There are a number of algorithms that can be used to estimate the location of the accessory pathway (AP). Many of these algorithms can be found in smartphone apps, I use EP Mobile which contains the following algorithms: