62 year old male presents to the emergency department complaining of chest discomfort.
** Update 05/19/2010 **
After oxygen and nitroglycerin the patient reports a significant decrease in pain.
An additional 12-lead ECG is captured.
There is now slightly less ST-elevation in leads V3 and V4.
Remember that a secondary ST-segment abnormality (as opposed to a primary ST-segment abnormality) should not "improve" with oxygen and nitroglycerin!
In other words, if this ST-elevation was caused just by the LBBB, it shouldn't be "getting better". Changing ST-segments suggest the dynamic supply vs. demand characteristics of ACS!
Now, let's go back to the initial 12-lead ECG. Is the ST-elevation in the anterior leads cause for concern?
Go back and read Identifying AMI in the presence of left bundle branch block (or paced rhythm). Remember, discordant ST-elevation = or > 5 mm is the least specific of Sgarbossa's criteria! That's why we use the modified rule that I learned from Dr. Stephen Smith of Dr. Smith's ECG Blog.
That criterion states that discordant ST-elevation should not be more than 0.2 (or 20%) the depth of the S-wave in the setting of left bundle branch block (ST/S ratio).
Using that criterion, how does this ECG measure up? Let's take a look.
Ladies and gentlemen, we have a winner!
The patient was ultimately cathed and angiography revealed 100% occlusion of the LAD.
Does it get any more difficult that that? If Dr. Smith's decision rule works this great, shouldn't we be shouting it from the rooftops?
Discordant ST-elevation in LBBB or paced rhythm
Identifying AMI in the presence of LBBB
Sgarbossa's criteria - new graph
"New" LBBB - What's the big deal?
New left bundle branch block is a poor indicator of coronary occlusion - Dr. Smith's ECG Blog
STEMI best seen in PVC (Dr. Smith's ECG Blog)