This is the conclusion to 47 year old male: Holiday Indigestion. Thanks go to a long time reader Nicholas Eisele for this holiday case! Editor's Note: sorry for the delay, it helps to press "publish"!

When we left off, our patient was in the back of the truck with a burning sensation radiating to his back. We had run a 12-Lead ECG and our partner was wondering which facility you wanted him to drive to.

To answer that question, we should look at the 12-lead!

This 12-Lead shows a normal sinus rhythm at 70 bpm without ectopy or bundle branch block. A case could be made for incomplete right bundle branch block given a QRSd of ~110ms. Strikingly we have ST-depression in I, aVL, and V1-V5 with ST-elevation in lead III. Anytime you see flat or downsloping ST-depression in aVL you should look for elevation in the inferior leads (typically III). When present, it is almost certainly an inferior wall MI.

Many readers commented that the ST-depression in V1-V5 could be either a sign of a posterior wall MI or a "anterior ischemia". It is important to remember that ST-depression from ischemia does not localize! This concept is so important, I'm going to list it again:

ST-depression from ischemia does not localize.

Traditional evaluation of ST-depression has taught that focal ischemia may cause localized ST-depression, however, this is not the case. Subendocardial ischemia causes diffuse ST-depression and will not be found in a localized pattern. Any time you have localized ST-depression you must consider it to be a reciprocal change first!

In our case, we have ST-elevation in lead III which clinches the diagnosis of an inferior wall myocardial infarction with possible posterior extension. A subsequent ECG revealed evolving ST-elevation in the inferior leads:

Remember, all patients who receive one 12-Lead should at least receive a second 12-Lead! If you were not comfortable activating a STEMI from the first clean tracing, serial 12-Leads provide improved diagnostic sensitivity. A single 12-Lead may only identify ~80% of STEMI patients.

The paramedics in this case recognized this fact, activated a STEMI alert, and transported the patient to their nearest PCI center. The in-hospital ECG showed continued evolution of the IWMI with the most impressive elevation and depression of the patient's clinical course:

They achieved an impressive 83 minute first medical contact to balloon time with one stent placed in the RCA.

We hope you've enjoyed this case as much as we did, but more importantly this case presents some great teaching points:

• Sometimes STEMI patients will have atypical symptoms.
• A single ECG is not enough to detect all STEMI patients, serial 12-Lead ECG's should be acquired on all patients who receive one.
• ST-depression from ischemia does not localize, localized ST-depression should be considered a reciprocal change until proven otherwise.