EKG 2 answer

Answer and ECG submitted by Dr. Eli Brown.

Thanks Richie/Shin. Good work in spotting the “widow maker. “ I would like to point out that this patient actually has poor R-wave progression. That, along with the QS complexes (III, aVF, V4), should raise suspicion for a subacute to chronic pathology. This patient was called in as a STEMI notification, largely because of the ST segments in V3-V4. Persistent ST elevation, however, can be seen indefinitely in up to 60% of patients with a previous anterior transmural MI and is frequently confused with an acute STEMI (1). These patients may proceed toward reperfusion therapy unnecessarily when presenting with ischemic symptoms such as chest pain or shortness of breath. This patient was not complaining of chest pain and should not have been taken to the catheterization lab acutely as a STEMI. That said, she probably should not have been stressed either given the concern for Wellens syndrome.

There were no previous EKG’s available to compare, but of note 80% of patients with persistent anterior ST elevation have a left ventricular aneurysm (2). In fact, the morphology of persistent ST elevation after an old myocardial infarction is often referred to as “ventricular aneurysm” regardless of whether or not an anatomical aneurysm is present. In addition to persistent ST elevation, QS-waves are commonly seen in leads V1-V4 indicating a complete loss of anterior electrical forces during depolarization.

Regardless, it can be very challenging to differentiate LV aneurysm from acute MI in the setting of ST elevation. One study by Dr. Smith et al. from Hennepin County looked at the ratio between T wave and QRS amplitudes in leads V1-V4. It was a small retrospective study, but in short his conclusion was that an acute MI should present with large T-wave amplitudes relative to the QRS, while a LV aneurysm should demonstrate a smaller T/QRS ratio. When the sum of T-wave amplitudes were divided by the sum of QRS complexes in leads V1-V4, the value was less than 0.22 in 20 of 22 patients with echocardiography-confirmed left ventricular aneurysms (3). In this patient the T-waves were negative in V2-V4 making the ratio significantly less than 0.22.

Upon arrival to the ED, a repeat EKG was obtained and presented to cardiology. After much debate whether she met the criteria for an immediate catheterization, the patient was taken to the catheterization lab for a diagnostic study with the explanation that if a lesion were to be identified, she would need to undergo a stress test prior to having any stents placed. Ultimately, the catheterization showed… triple vessel disease, LVH and a LV aneurysm.

1. Mills RM, Young E, Gorlin R, Lesch M. Natural history of S-T segment elevation after acute myocardial infarction. Am J Cardiol 1975;35(5):609-14.

2. Visser CA, Kan G, Meltzer RS, Koolen JJ, Dunning AJ. Incidence, timing and prognostic value of left ventricular aneurysm formation after myocardial infarction: A prospective, serial echocardiographic study of 158 patients. Am J Cardiol 1986;57(10):729-32.

3. Smith SW. T/QRS amplitude ratio best distinguishes the ST elevation of anterior left ventricular aneurysm from anterior acute myocardial infarction. American Journal of Emergency Medicine 2005;23(3):279-87.