ECG of the Week - 3rd August 2015 - Interpretation

This ECG is from a 50 year old male who presented with 2 hours of typical chest pain on a background of progressive dysponea for the preceding 2 weeks. Past medical history of hypertension, diabetes and hyperlipidaemia. 
Check out the comments from our original post here.

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Rate:

• 84

Rhythm:

• Regular
• Sinus Rhythm

Axis:

• LAD

Intervals:

• PR - Normal (~200ms)
• QRS - Prolonged (200ms)
• QT - 400ms

Segments:

• ST Elevation leads II, III, aVF, V1-5
• ST Depression leads aVR, aVL, V6
• ST changes are discordant i.e. in the opposite direction to the QRS vector
• Discordant change is 'appropriate' in magnitude

Additional:

• T inversion leads aVR, aVL, V6
• Again discordant to QRS vector
• Deep Swave V1-4
• Notching R wave in V6

Interpretation:

• LBBB
• Sgarbossa / Modified Sgarbossa Negative

• Duration of LBBB unknown - nil prior ECG's available

What happened ?

The patient was referred to the cardiology team given his typical history and risk factors.
He underwent early coronary angiogram which revealed multi-vessel diffuse disease (<50% stenosis).

An echo showed:

• Mod to severe dilated left ventricle with severe global impaiment - EF ~21%
• Mild diastolic dysfunction
• Elevated pulmonary artery pressure with normal right ventricular size & function

The patient was given lifestyle education and commenced on ACE-inhibitor, statin, diuretics and beta-blocker.

'New' LBBB remains in the Australian Heart Association guidelines as a trigger for reperfusion therapy. However, the last update of these guidelines was in Sept 2011 and since we have seen a move away from 'new' LBBB or 'presumed new' LBBB being a trigger for urgent reperfusion. The American Heart Association 2013 guidelines removed LBBB as an indication for urgent reperfusion. There is clear variation in international guidelines on this topic and clinicians need to be aware of their own local policies and practices regarding reperfusion criteria.

There are some interesting posts on LBBB significance in ACS here:

• "New" Math: LBBB Does Not Equal STEMI - Medscape
• New Left Bundle Branch Block is a poor indicator of coronary occlusion - Dt Smith's ECG Blog
• R.E.B.E.L. ECG of the Week: LBBB and STEMI - Sgarbossa & Modified Sgarbossa

References / Further Reading

Life in the Fast Lane

• LBBB
• AMI in LBBB - Sgarbossa Criteria

Textbook

• Chan TC, Brady WJ, Harrigan RA, Ornato JP, Rosen P. ECG in Emergency Medicine and Acute Care. Elsevier Mosby 2005.