This is the discussion for 50 year old male CC: Chest Pressure.
We could not have been happier at the number of insightful comments we received on this case! Many of you caught on to our purpose for this case as we could not have picked a better borderline example!
When we last left our crew they were preparing to transport a 50 year old male who appeared acutely ill. Their first 12-Lead ECG suffered from excessive baseline wander, but appeared to have some ST-elevation present. Attempts were made at improving the quality of the tracings with little success.
Here is the initial 12-Lead ECG, this time with the computerized interpretation included:
This 12-Lead ECG shows marked baseline wander, sinus bradycardia, ST-elevation of at least 1 mm in II, aVF, and V4-V6 with ST-depression in leads aVR and V1. The monitor's algorithm believes the ST-changes are the result of Early Repolarization.
They attempted to troubleshoot the baseline wander with patient coaching, and after two more attempts they captured the following 12-Lead ECG; again with the computerized interpretation included:
This 12-Lead ECG also shows marked baseline wander, a sinus rhythm, ST-elevation of at least 1 mm in II, aVF, and V4-V6 with ST-depression in leads aVR and V1. In this tracing, just 2 minutes later, the monitor's interpretation has changed to read the ominous *** ACUTE MI SUSPECTED *** message, suggesting an inferiolateral infarct pattern.
Between these two 12-Lead ECGs we can clearly see that ST-elevation is present in leads II, aVF, and V4-V6 with ST-depression clearly visible in aVR and V1. It is difficult to tell with the baseline wander whether any PR-segment changes exist or if the J-point in aVL is depressed.
At this point our differentials should include:
- Acute inferiolateral myocardial infarction
- Early repolarization
Given our patient's recent history of strep throat, diffuse ST-elevation, concave-up T-waves, and ST-depression in aVR and V1 we should strongly consider pericarditis. The baseline wander present makes accurate evalution of the PR-segment difficult, but a case could be made for PR-elevation in aVR. Compare our tracings with the discussion to 39 year old male CC: "Sick".
However, given the presentation of typical MI symptoms and a borderline ECG (albeit without reciprocal changes), we have no conclusive means of ruling out an inferiolateral myocardial infarction. If your service area has the ability to, it would be beneficial to transmit these borderline ECGs to a receiving facility for a second opinion. Compare our tracings with the discussion to 77 year old female CC: Chest Pain.
Our crew found themselves in quite the pickle!
In these instances it is prudent to err on the side of the patient and treat this as a STEMI, which is exactly what the crew did.
Upon arrival at the PCI center the following ECG was acquired:
The ED 12-Lead shows a normal sinus rhythm without ectopy. ST-elevation of at least 1 mm exists in leads II, aVF, and V4-V6. ST-depression is present in lead aVR. The monitor's interpretation is unknown.
The ED physician concurred with the activation and the patient was sent for an emergent cardiac catheterization.
No culprit lesion was found and the crew was later informed the patient was being treated for pericarditis.
This case represents a false positive, however, it is the author's opinion that this case does not represent an inappropriate field activation due to the borderline field ECG.
Some clues on the 12-Leads that favor pericarditis include a lack of reciprocal ST-depression in aVL, a normal QTc, concave-up ST-segments, and ST-depression in aVR and V1. When available echocardiography could be utilized to look for wall motion abnormalities prior to sending this patient to the cath lab.
When designing a STEMI system to provide maximal benefit to the patient a certain false positive rate is to be expected. The system must recognize the existence of this gray area and allow for overtriage in order to be successful for both the patients and their providers.
- What are your thoughts on the conclusion to this case?
- How many attempts at acquiring a clean tracing should be made?
- If your system allows Paramedic activation of STEMI, are you provided constructive feedback?