77 year old female CC: Chest pain – Conclusion

This is the conclusion to 77 year old female CC: Chest pain.

Thanks for all the great comments! You guys never disappoint.

Let's take another look at the initial 12-lead ECG.

Here is one of the serial 12-lead ECGs taken about 15 minutes later.

It's subtle but there are clear changes in QRS, ST and T wave morphology between these 12-lead ECGs (nice catch NJ Newbie). This suggests that a dynamic process is at work. Namely, the dynamic oxygen supply vs. demand characteristics of true ACS.

But is it a STEMI?

There are several things that make this case confusing.

In the first place, PR-depression is present in several leads, and we're already thinking about the possibility of pericarditis because of the unusual constellation of ST-elevation (and the atypical nature of the chest pain). But, women often present with atypical symptoms!

Second, pathological Q-waves are present in the inferior leads (nice catch Dave O and Neil H) but he is correct in that this finding could be old or new. Normally lead aVL is our "go to" lead to help confirm acute inferior STEMI and while there is the tiniest little "dip" after the J-point in this lead, I'm not prepared to call it a reciprocal change.

Third, low voltage is present throughout the 12-lead ECGs which makes analysis of the ST-segments and T-waves more difficult. To help, we can use the "rule of proportionality". That means that our threshold for ST/T wave abnormalities is lower when the QRS complex is smaller. In other words, we don't necessary need 1 (or 2) mm of ST-elevation to be significant, especially when the QRS complex is < 5 mm in amplitude. We also need to be suspicious when the T-waves appear disproportionately large for the size of the QRS complex (again, nice catch Dave O).

Let's take a closer look at some of the most suspicious leads. Here I have used PowerPoint to "stretch" the leads vertically while preserving the ST/QRS ratio.

These T-waves are way too large considering the relatively small size of the QRS complex.

But what about ST-elevation?

Let's take a close look at leads V4 and V5 (I'd include lead V3 but there's some wandering baseline that makes finding the TP segment too difficult).

First lead V4 (again stretched vertically while preserving the ST/QRS ratio).

When we compare the TP segment to the J-points we can see that ST-elevation is clearly present.

Next we'll look at lead V5 (stretched vertically while preserving the ST/QRS ratio).

Again, when we compare the TP segment to the J-points we see that ST-elevation is present.

Just "eye-balling" it we can also appreciate ST-elevation in lead V3. So, do we have ST-elevation in 2 or more contiguous leads?

Yes.

In this case, the cardiac cath lab was activated while paramedics were still out in the field and the cath team was waiting when the patient came through the door.

So, what did they find?

Diagnosis: Acute ST-elevation myocardial infarction