An Interesting ECG Case
A 50-year-old male has a syncopal episode after donating blood and EMS is called.
He is obese (BMI 30), has hypertension (on medication his home BP averages 135/85), DM2 (hemoglobin A1C 6.5 on no treatment), has dyslipidemia (on high dose statin LDL 1.9 mmol/L), has a brother with STEMI age 49.
Five years ago, he presented with chest pain and a high sensitivity troponin rise over from 16 to 498 ng/L over 12 hours.
At that time his initial ECG #1, was:
12 hours later ECG #2, was:
Coronary angiography demonstrated a 99% proximal LAD lesion that was successfully stented. No recurring chest pain has occurred since then.
Today he donated blood. After, he went to the mall with his wife. He noticed bleeding at his IV site and subsequently had syncopal episode. There was spontaneous return of consciousness. No seizure-like activity occurred. He denies head trauma and denies any injury elsewhere. He had similar syncopal episodes previously.
Vital Signs- afebrile, HR-65-68, BP: 97/59, O2 saturation 99% on room air.
Physical exam is otherwise normal.
Today, ECG #3, by EMS on scene:
ECG Interpretations:
#1. Normal sinus rhythm, normal tracing.
#2. New T ischemic wave abnormalities V1-4
#3. New ST elevation, concave upwards, antero-lateral leads
TNT 6 ng/L, 1 hour later 4 ng/L.
Questions:
1. Is this a STEMI?
2. What is the diagnosis?
Answers:
1. Not a STEMI, ST elevation due to “normal variant early repolarization”.
2. Diagnosis is “vasovagal syncope”.
Early Repolarization on ECG: Overview and Differentiation
Early repolarization (ER) is a benign ECG pattern characterized by:
J-point elevation (≥ 0.1 mV) in at least two contiguous leads, often with a notching or slurring of the terminal QRS complex.
Concave (“smiley”) ST-segment elevation without reciprocal changes.
Stable T waves that do not evolve over time.
Most commonly seen in the inferior leads (II, III, aVF) and/or lateral leads (V4–V6).
Prevalence & Variability
Occurs in 2-5% of the general population, but up to 10-20% in athletes.
Can be transient or variable within the same individual, often influenced by autonomic tone (e.g., more pronounced at rest or during vagal predominance, such as in this case).
Demographic Associations
More common in younger individuals (<50 years), particularly males.
More frequent in Black individuals compared to other racial groups.
Higher prevalence in athletes and physically active individuals.
Differentiation from Pericarditis & STEMI
1. Pericarditis:
J-Point & ST-Segment:
Diffuse concave ST-segment elevation across multiple leads (not localized to a vascular territory).
J-point elevation without QRS notching (unlike ER).
PR-Segment Changes:
PR-segment depression in most leads (except aVR, which may have PR elevation).
T-Waves:
Do not invert acutely (in contrast to STEMI, where inversion follows ST elevation).
Late inversion (days to weeks) common. (See after ST segments normalize)
Reciprocal Changes:
Absent (except in aVR, where PR is elevated and ST is depressed).
2. STEMI:
J-Point & ST-Segment:
Marked J-point elevation with convex (“tombstone”) ST-segment elevation in a vascular distribution (e.g., anterior, inferior, or lateral leads).
J-point is often indistinct, merging into the ST segment without slurring or notching.
PR-Segment Changes:
No PR depression (helps differentiate from pericarditis).
Reciprocal Changes:
Present in opposite leads (e.g., inferior STEMI shows reciprocal ST depression in lead I and aVL).
T-Wave Evolution:
Hyperacute T waves in early stages.
T-wave inversion may start prior ST elevation resolves. When seen after ST resolution, T wave negativity considered “evolution of the electrocardiogram” post acute MI.
