Here is the discussion for “71 year old male: chest discomfort”
let’s review the prehospital 12 lead:
Here are the precordial leads blown up:
There is slight ST elevation in V1, ST elevation in V2 (saddleback morphology), as well as slight ST elevation in V3 and V4. The STE in V3 and V4 is between 1 and 2 millimeters at 60 milliseconds after the J-point. This looks like what we might see in normal variant, but we have no idea what the baseline ECG would look like, and with the patient’s presentation must be suspicious. Additionally, the T wave in V3 has a “hyperacute” feel to it.
The Paramedic, known to be an excellent one, was approrpriately concerned about the above findings. A STEMI alert was called, and the patient was taken to the community hospital, which was closest but is also a PCI center.
Another wrinkle is the “saddleback” morphology of the ST elevation in lead V2. If you are a frequent reader of Dr. Smith’s ECG Blog you know that the “saddleback” morphology is rarely due to occlusion myocardial infarction (OMI). But, rarely doesn’t mean never.
Upon arrival at the hospital, the following ECG was acquired approximately 22 minutes after the last prehospital ECG:
There are significant changes from the prehospital ECG.
Here are V1-V3 side by side:
Most notably, the “saddleback” morphology is no longer present. The ST elevation in V2 and V3 appears to be slightly less, but there is a straightening of the ST segment. You can also see slight T wave inversion in V3.
V4-V6 side by side:
Compared to the prehospital ECGs, you can clearly see reperfusion T waves (up-down) in V4-V6.
At this point, the STEMI alert was cancelled. The patient did go to the cath lab, but benchmark times are not available due to the cancellation of the STEMI alert.
During cath, the patient was found to have a 90% stenosis of the proximal-mid LAD, which was stented. Flow was noted to be TIMI-1 prior to intervention, with restoration of TIMI-3 flow. This was classified as NSTEMI.
The hospital ECG proves that there was indeed occlusion. The artery was closed at the time of the prehospital ECG, and spontaneously reopened, resulting in the reperfusion ECG (Wellens’) acquired upon arrival at the ED. The patient was expected to recover well.
Although the ECG that showed the most dynamic changes was acquired at the hospital, there are times when these types of changes could easily show up in the field. The practice of serial ECGs in the field can not be understated, and often times it is the dynamic changes that clinch the diagnosis.