An interesting ECG case -inferoposterior STEMI with CHB

An inferoposterior STEMI with CHB. 

SOURCE: https://litfl.com/inferior-stemi-ecg-library/ (Example 8)

Let’s walk through this ECG together: 

1.  ST elevation in leads II, III and aVF, consistent with an inferior STEMI

2. ST depression in V1 and V2, suggests posterior involvement 

3. There are reciprocal changes in I and aVL

   This fits with an acute inferoposterior STEMI

Don’t forget to look at the rate and rhythm:

1.  The rhythm is sinus as there are upright p waves in leads I and II 

2.  No 1:1 relationship between the P waves and QRS complexes

3.  On lead II rhythm strip, PR interval prolongs before a beat is dropped (1st red circle below)

4.  This may lead you to think that the patient has 2nd degree AV block, Mobitz 1

   However, last PR interval too short to conduct before the QRS complex (2nd red circle)

   This suggests AV dissociation and complete heart block (CHB)

In summary, this ECG represents an inferoposterior STEMI with CHB.

Approximately 20% of inferior STEMIs are associated with CHB.

SOURCE: https://litfl.com/inferior-stemi-ecg-library/ (Example 8)