This is the conclusion to 88 year old male CC: Chest pain. You may wish to go back and review the history and clinical presentation.
First, let's look at the rhythm strip.
This shows an undetermined regular rhythm at a rate of about 60 with demand ventricular pacing.
This is an oversimplification but as long as the intrinsic rhythm has an R-R interval of 1000 ms or less (blue arrows for reference) the pacemaker will inhibit itself because it's not needed.
Then we see the first 12-lead ECG.
Lead V1 is often a good place to see atrial activity. Now we can see flutter waves which explains why there is no atrial pacing (assuming this is a dual chambered pacemaker). You will note that the "wide" QRS complexes in the 12-lead ECG are exactly 1000 ms apart and are functioning in an apparent demand capacity which means these complexes are almost certainly paced.
As at least one person mentioned in the comments a typical paced rhythm with the pacing lead in the apex of the right ventricle will show LBBB morphology (this ECG shows RBBB morphology) so this is a bit unusual. However, in this modern day and age of mutlisite pacing none of these rules are set in stone.
I will say, however, that when I first saw this 12-lead ECG the T-waves in the right precordial leads (V1-V3) looked unusually large to me even though they are appropriately discordant with the QRS complex.
Now let's look at the next 12-lead ECG.
Interestingly, the intrinsic rhythm does not look particularly concerning in the right precordial leads (V1-V3). However, I do see a problem! To demonstrate I'm going to place leads V5 and V6 from 12-Lead 1 and 12-Lead 2 side-by-side.
This is a subtle finding but note the loss of upward concavity in the ST-segments between 12-Lead 1 and 12-Lead 2. In other words, there is a "straightening" of the ST-segment (it's not curved upward anymore) and that's bad!
Now let's look at the final 12-lead ECG.
This ECG appears to show acute lateral STEMI. Would it be better to have seen a previous 12-lead ECG with paced rhythm in the left precordial leads (V4-V6)? Absolutely! But clearly there is excessive discordance in leads V5 and V6 and the T-waves look hyperacute.
Here is the ECG that was taken in the emergency department.
These changes were not appreciated by the paramedics, the ED physician or the cardiologist.
- CKMB 2.14
- CPK 58
- Trop < 0.01
- K+ 2.8 (low)
- Na 142
- Calcium 5.8 mg/dL (critical) – non-ionized
- Renal profile WNL
- CPK 254
- CKMB 30.03
- Trop 0.341
CT was negative for PE or aneurysm.
It was also noted in the chart that the patient had a history of AF and MVP S/P repair (could this explain the RBBB morphology with the paced rhythm?).
This was ultimately diagnosed as an acute coronary syndrome but not a STEMI. The case was handled medically (did not go to the lab) and the patient was discharged home.
Was it a missed STEMI? I can't say conclusively due to the abnormal lab values but I'm curious to hear what Stephen Smith, M.D. has to say!