Original case from Brandon Fainstad, MD.
Edits and graphics by Yilin Zhang, MD.
- Practice interpreting ECGs
- Differentiate between benign J-point elevation and ST-elevation MI (STEMI)
- Manage a patient with STEMI
32 year old man developed substernal chest pressure and SOB while playing tennis at 1830. The symptoms did not resolve with rest. He took aspirin 182mg and asked his friend to take him to the ED. About 15 min after arriving in the ED his symptoms self-resolved. His PMH is notable for hypertension but does not take any medications. He smokes 1 ppd but denies any other substance use.
On exam, he is afebrile, HR 86, BP 165/82, RR 20, SpO2 96% RA. He is breathing comfortably, lung exam clear to ausculation bilaterally. His cardiac exam reveals RRR, no murmurs, skin is warm with good distal pulses with non-elevated JVP.Click for ECG Interpretation
How can you differentiate between benign early re-polarization (J point elevation) and STEMI?
ST segmental elevation is measured at the J-point.The J point is normally at or near the isoelectric baseline but can be elevated in 1- 13% of the general population1. The best way to establish if this is J point elevation is to compare the J point to a prior ECG (not available in this case).
J point elevation is typically the highest in V2 and is more common in African Americans and men. Upper limits of normal J point elevation1:
- Men < 40 yo: 0.25 mV (2.5 mm)
- Men > 40 yo: 0.2 mV (2 mm)
- Women: 0.15 mV for women (1.5 mm)
- All other leads: 0.1 mV (1 mm)
What is the criteria for STEMI?
Per the European Society of Cardiology/ ACCF/ AHA/ World Heart Federation Task Force for the Universal Definition of Myocardial Infarction:
- Men < 40 yo: >2.5 mm
- Men > 40 yo: >2 mm
- Women: >1.5 mm
- All other leads: >1 mm in ≥2 contiguous leads
Note that these are the same criteria as the upper limit of normal for J point elevation.
When do you want to get another ECG?
CASE CONTINUED:Click for ECG interpretation
Does this make you more or less worried? What are your next steps in management?
- Call code STEMI (or equivalent to mobilize cardiology and cath lab for early reperfusion)
- Asa 162 mg (for a total of 325 mg) if not already done
- Heparin drip
- Ask the interventionalist for their preference of PGY12 inhibitor (likely prasugruel or ticagrelor > clopidogrel)
Additional medications could include:
- Nitroglycerin and/or morphine if recurrent chest pain
- Supplemental O2 if SpO2 >90%
No interventions were done. More than an hour goes by before the subsequent ECG.Click for ECG interpretation
Finally, a code STEMI was called, received the above listed medications and went to the cath lab with the following angiography.
Based on the ECG what vessel is likely involved and at what level is the occlusion?
Post PCI 23:43
A 90% occluding lesion was seen in the mid LAD (culprit). Post-PCI with a drug-eluting stent, there was 0% residual stenosis across this lesion. He tolerated the procedure well, remained chest pain-free and was discharged the next day on aspirin, atorvastatin, clopidogrel, lisinopril and metoprolol. At a 4 week follow-up, he was playing 2hr of tennis without chest pain or shortness of breath and had quit smoking.
TAKE HOME POINTS:
- The J point is the end of the QRS and start of ST segment. ST elevation is measured at this point.
- J point can be elevated in benign repolarization, which is seen in 1-13% of the general population. New elevations are more likely to represent ischemia.
- Development of new arrhythmias (e.g. atrioventricular block) in the setting of J point elevation strongly suggests acute ischemia.
- Mirvis GM & Goldberger AL. Electrocardiography. In: Mann DL, et al (eds.) Braunwald’s Heart Disease: A Textbook of Cardiovascular Medicine. Philadelphia, PA. Elsevier Saunders. 2015: 114-154.
- Ibanez J, et al. 2017 ESC Guidelines for the management of acute myocardial infarction in patients presenting with ST-segment elevation: The Task Force for the management of acute myocardial infarction in patients presenting with ST-segment elevation of the European Society of Cardiology (ESC). Eur Heart J. 2018; 39(2):119-177.
- O’Gara PT et al. 2013 ACCHF/AHA Guideline for the Management of ST-Elevation Myocardial Infarcation: A Report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Circulation. 2013; 127:e362-e425.