Here is a case of an 89 year old woman who had syncope but no chest pain or shortness of breath. Her initial EKG (#1) shows some nondiagnostic ST depression in V4-V6, probably due to LVH. She has a troponin of 0.13 ng/ml (ref range up to 0.09).
She is admitted, her trop peaks at 0.23, her next day EKG done 8 hours later is shown below (#2) and shows some terminal T inversion in V3, consistent with the positive trop and suggesting tight LAD occlusion but open artery (T inversions are "reperfusion T waves; an inverted T wave is a sign of an open artery and an upright T wave is a sign of occlusion or re-occlusion). Echo the next day is normal. She is diagnosed with "demand ischemia" and discharged home.
The patient returned with another episode of syncope 15 days later. She had no other symptom except weakness; none whatsoever. She had the following EKG at 0700:
Here there is 4 mm of ST elevation that can only be due to myocardial ischemia. If there is any doubt, then the presence of new ST elevation and T inversion in I and aVL should erase that. If there is still any doubt, the loss of R-wave amplitude in V2 and V3 should erase that as well. The inversion of the T wave in aVL and V2 suggests an open artery. However, this is a very strange looking Wellens' T wave because of the marked ST elevation.
The treating physician contacted the cardiologist immediately, but the cardiologist was not convinced, mostly because of the minimal symptoms and partly because it is not the classic morphology of anterior STEMI due to persistently occluded LAD, which should have upright T waves.
So they recorded another EKG at 0720:
Now the ST elevation is unmistakable, even with the persistently inverted T waves. But because the patient was asymptomatic, the cath lab was not yet activated. A bedside echo suggested anterior wall motion abnormality.
Another EKG was done at 0739:
This shows even more ST elevation. The patient was still asymptomatic. An initial troponin returned at 12 ng/ml. The cath lab was activated. There was a ruptured plaque with thrombus in the LAD, with some flow still (accounting for the inverted T waves).
Fortunately, the physicians were attentive and kept ordering frequent serial EKGs.
Learning point: some EKGs represent STEMI no matter what the symptoms, until proven otherwise by angiography.