Two STEMI Mimics You've Got to Know!

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This year we are very fortunate to have Dr. Amal Mattu, EKG Jedi, as teaching faculty for our 39th Maine Medical Center/Maine ACEP Winter Symposium. In this lecture, he helps us differentiate septal STEMIs from other potentially life threatening mimics.

For more information on our winter symposium, click here.

 

Case Presentation #1

chest pain.jpg

  • You are working the overnight shift and an 81yo male presents with chest pain, shortness of breath. HR 137, BP 105/50, 36C, RR 26, 95% O2 saturation on room air

  • As he is brought in by ambulance, the paramedic presents the prehospital ECG below… do you activate the cath lab?

 
Courtey of Dr. Amal Mattu

Courtey of Dr. Amal Mattu

  • On first glance, it appears that there is ST elevation in V1, V2, AVR and some in lead III (suggesting a septal STEMI)

  • However, a closer look at lead I reveals a large S wave (rightward axis) - this is atypical for a STEMI

  • So if this is not a STEMI, what’s going on?

 

Righward Axis and Septal ST Elevation

  • For an EKG with septal ST elevation and rightward axis, there are three main diagnosis to consider before STEMI:

    • Acute pulmonary hypertension (i.e. massive pulmonary embolism)

    • Hyperkalemia

    • Sodium channel blocking drug toxicity

 

EKG Findings in Large, Potentially Destabilizing Pulmonary Embolism

  • TW inversion in right precordial leads

  • ST elevation and depression (especially STE in V1-V2, AVR, III)

  • Tachycardia (sinus, atrial fibrillation)

  • Right heart strain

    • Rightward axis

    • Incomplete right bundle branch block

    • TW inversion (especially anteroseptal +/- inferior leads)

    • ST changes, including STE in rightward leads (V1, V2, AVR, III)

Case Resolution

  • A history was obtained making the diagnosis of hyperkalemaia or sodium channel blocker toxicity unlikely

  • A bedside echo showed a dilated RV with septal deviation, leading to the ultimate diagnosis of large pulmonary embolism

Bedside echo showing right ventricular dilation and septal deviation during diastole suggesting pulmonary embolism (courtesy of Dr. Amal Mattu)

Bedside echo showing right ventricular dilation and septal deviation during diastole suggesting pulmonary embolism (courtesy of Dr. Amal Mattu)

 

Case #2

  • 47 yo insulin dependent diabetic male who arrives by ambulance for 12 hours of nausea, vomiting and burning epigastric pain

  • The ED tech hands you the ECG below… do you activate the cath lab?

Courtesy of Dr. Amal Mattu

Courtesy of Dr. Amal Mattu

  • On first glance, it appears that there is ST elevation in V1, V2, and AVR suggesting STEMI

  • However, you may notice the S wave in lead I and a righward axis

  • You think of PE, but your patient has no suggestive history, exam or risk factors

  • So if this is not a STEMI or PE, what else was on our differential for pseudo-septal STEMI and rightward axis?

    • Hyperkalemia

    • Sodium channel blocker toxicity

  • Upon further view of this EKG, it is apparent this patient has some peaked T waves

  • Laboratory results reveal a potassium of 7.3, which improves nicely with Calcium, Sodium Bicarb, Glucose/insulin

 
 
summary image.jpg
 

  • Large pulmonary embolism, hyperkalemia and sodium channel blocking drugs can often mimic a STEMI (especially in rightward leads)

  • A septal STEMI, rarely produces right axis deviation

  • When there is a rightward axis in an apparent “STEMI” first consider a large PE, hyperkalemia and sodium channel blocker toxicity

 

Tired of reading? Watch Dr. Mattu discuss two stemi Mimics you’ve got to know

 

Prefer to absorb your Med-Ed through your wonderful powers of hearing? Check out our podcast by clicking here.

 
Amal Mattu headshot.jpg

Amal Mattu, MD, FAAEM, FACEP

Professor and Vice Chair of Academic Affairs

Department of Emergency Medicine

University of Maryland School of Medicine

Twitter: @amalmattu

 

Content and original authorship by Amal Mattu, MD

Edited and Posted by Jeffrey A. Holmes, MD

References:

  1. Shopp, et al. Findings from 12-lead electrocardiography that predict circulatory shock from pulmonary embolism: systematic review and meta-analysis. Acad Emerge Med 2015. [Pdf]

  2. Dibgy, et al. The value of electrocardiographic abnormalities in the prognosis of pulmonary embolism: a consensus paper. Ann Noninvasive Electrocardiol 2015.[Pdf]

  3. Zhan, et al. Electrocardiogram patterns during hemodynamic instability in patients with acute pulmonary embolism. Ann Noninvasive Electrocardiol 2014.[Pdf]

  4. Kukla, et al.  Electrocardiographic abnormalities in patients with acute pulmonary embolism complicated by cardiogenic shock. Am J Emerge Med 2014.[Pubmed]

  5. Abarca, et al. ECG manifestations in submassive and massive pulmonary embolism. Report of 4 cases and review of the literature. J Electrocardiol 2014.[Pubmed]

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Amal Mattu, MD

Amal Mattu, MD has had a passion for teaching and writing about emergency cardiology since he joined the faculty at the University of Maryland School of Medicine. He has authored or edited 20 textbooks in emergency medicine, including eight focused on emergency cardiology and electrocardiography. He has also served as primary Guest Editor for Cardiology Clinics three times. He lectures nationally and internationally on emergency cardiology topics and has helped to create conferences focused on this area. Dr. Mattu is currently a tenured Professor, Vice Chair of Education, and Co-Director of the Emergency Cardiology Fellowship for the Department of Emergency Medicine at the University of Maryland School of Medicine.