EMS responds to a 76 year old male with dispatch complaint of shortness of breath.
At the time of EMS arrival, the patient appears acutely ill. He is slightly diaphoretic but not overly anxious. He admits to chest discomfort but denies nausea, vomiting, or palpitations. No jugular venous distension. Breath sounds are clear bilaterally.
He reports his past medical history as “healthy” and takes no prescription medications.
- Onset: While walking (he takes a long walk every day)
- Provoke: Nothing makes the pain better or worse
- Quality: Described as pressure
- Radiate: The pain does not radiate
- Severity: Started mild and progressed to 8/10 in severity over 30 minutes
- Time: The patient experienced similar symptoms 2 days ago but symptoms resolved with rest
Vital signs are assessed.
- RR: 18
- Pulse: 58
- NIBP: 155/90
- SpO2: 98% on room air
The cardiac monitor is attached.
A 12 lead ECG is captured.
Let us assume for the sake of discussion that you live in a rural community.
You are 25 minutes away from your local receiving hospital (no cath lab) and 55 minutes away from a hospital in the next county over that is capable of primary PCI.
Do you bypass the local community hospital?
Should the cardiac cath lab be activated prior to your arrival?
This ECG shows LAD occlusion although it does not meet the guideline requirement of “new ST elevation at the J point in at least 2 contiguous leads of 2 mm (0.2 mV) in men or 1.5 mm (0.15 mV) in women in leads V2-V3 and/or of 1 mm (0.1 mV) in other contiguous chest leads or the limb leads.”
The problem with arbitrary mm criteria is that they do not take into account the depth of the S-wave. This is a violation of the rule of proportionality which states that repolarization is proportional to depolarization.
Also note that the T-waves a disproportionately large because they are hyperacute.
The mean R-wave amplitude between leads V1-V4 is less than 5 mm which essentially rules out early repolarization.
The ST-segments in lead V1 are upwardly convex with terminal T-wave inversion (something I have noticed on many occasions with LAD occlusion).
There is also a flattening of the ST-segments in the inferior leads that probably represents reciprocal changes.
Although the treating paramedics were concerned about the ECG this was not recognized as acute STEMI in the field.
However, the patient was delivered to a PCI-hopsital. The initial ECG in the Emergency Department (which I do not have) was unequivocal and the cardiac cath lab was activated. The patient was found to have 100% occlusion of the left anterior descending artery (LAD).
O’Gara P, Kushner F, Ascheim D et al. 2013 ACCF/AHA Guideline for the Management of ST-Elevation Myocardial Infarction: Executive Summary: A Report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Circulation. 2012;127(4):529-555. doi:10.1161/cir.0b013e3182742c84.