A 68 y.o. female with an unknown past medical history presents for shortness of breath. On arrival, the patient is hypoxic to 87% on room air, tachypneic, and tachycardic to 120’s. She is not hypotensive. She appears to be in respiratory distress with crackles and wheezing throughout all lung fields. Although history is limited secondary to respiratory distress she is not endorsing chest pain.
Arrival EKG shows:
There is a rate of approximately 120. There is ST elevation in II, III, aVF as well as v1-v3. There is depression and inversion in I and aVL.
Should the cath lab be activated?
Looking a little closer at the EKG, there are signs of LVH as well as peaked T waves. We were able to obtain an old EKG for the patient that showed prior LVH as well as flat T waves in I and aVL. The old EKG however did not have the ST elevation noted above (except minimal elevation in v1-v3) and did not have the depressions noted above.
This was a scary looking EKG, however, there were some findings on the EKG that caught our eye. The patient was tachycardic with a rate ranging from 120-130 while on the monitor. Although you can manifest tachycardia with a STEMI, tachycardia should make you think about other possible etiologies and STEMI mimics. The EKG also had peaked T waves which made us consider hyperkalemia. LVH with strain can already cause a variety of EKG changes and hyperkalemia plus LVH with strain can create a scary looking EKG. One reassuring thing on the EKG was that the ST elevations remained concave rather than convex. We decided to empirically treat first with calcium, insulin, and glucose while we called interventional cardiology to discuss the case.
Repeat EKG showed:
The EKG changes have essentially resolved. The ST elevations have nearly resolved as well as the peaked T waves and reciprocal T wave inversions. When compared to prior EKGs in our system, this one appears nearly identical to prior.
After discussion with cardiology and review of the EKGs, the cath lab was not activated as this seemed to be more of a metabolic process and possibly LVH with strain rather than ACS. Further workup revealed that the patient had new onset renal failure with severe hyperkalemia. She was admitted to the ICU for further workup, care, and consideration of dialysis. Serial troponins were negative.
LVH with strain: (Of note this section borrows from Dr. Mattu’s ECG Weekly which I highly recommend. It is an amazing resource for EKG learning and cases)
It can be extremely difficult to differentiate LVH with a strain pattern versus cardiac ischemia. LVH can cause STE as well as ST depression and T wave inversions that can mimic ischemia. When in doubt, perform serial EKGs and compare with prior EKGs. Some features of LVH with strain:
* ST depression in any of: I, II, aVF, aVL, V4-V6
* Asymmetric T wave inversions
* ST elevation in aVR, V1-V3
Here are some LVH with strain EKGs to show how difficult it can be to differentiate between a strain pattern and ischemia:
ST elevation in aVR, v1, v2. ST depression and T wave inversions v4-v6, I, aVL, II, aVF. T wave inversions are asymmetric.
ST elevation v1, v2. ST depression v4-v6, II, aVF, asymmetric T wave inversions
Looking back at our patient’s EKG:
We see ST elevation in v1-v3 as well as the ST depression with asymmetric T waves in I and aVL. However the changes in II, III, avF are less consistent with LVH with strain given that they are elevated and not depressed or inverted. You also wouldn’t expect to find a lead III change in terms of elevation/depression with LVH with strain but instead could manifest a biphasic T wave.
This case demonstrates how difficult it can be to differentiate between LVH with strain and cardiac ischemia. When in doubt, activate the cath lab if the EKG is concerning. Time is muscle.
Take Home Points:
* Although tachycardia can occur in STEMI, always consider other mimics such as hyperkalemia, dissection, PE, etc. Sometimes the cath lab is not the best place for the patient.
* As Dr. Mattu would say, “Hyperkalemia is the syphilis of electrocardiography.” It can do anything to an EKG. If you are worried about hyperkalemia causing severe arrhythmia or EKG changes, empirically give calcium and see if the changes resolve.
* It is not unusual to see ST elevations in v1-v3 with LVH/strain pattern as well as diffuse ST depression with asymmetric t wave inversions.
* LVH with strain vs Ischemia is extremely difficult to delineate. Perform serial EKGs and compare to prior when able. If in doubt, activate.
Faculty Reviewer: Michael Tupper, MD