A 54‑year‑old woman presents with chest discomfort and mild dyspnea. Her ECG shows ST elevation in V2–V3. A clinician diagnoses “STEMI” and activates the cath lab.
A second clinician reviews the ECG and notes:
- Upward concavity
- J‑point notching
- Stable morphology compared to a prior ECG
- No reciprocal changes
- Normal hemodynamics
The correct diagnosis is early repolarization, not acute occlusion.
Mechanism‑Based Reasoning
Early repolarization is a benign variant caused by:
- Increased vagal tone
- Enhanced phase 1 repolarization
- J‑point elevation
Understanding the mechanism prevents misdiagnosis (for a more complete discussion, see Getting Acquainted With Ischemia and Infarction).
The Teaching Point
Pattern‑based learning encourages clinicians to equate “ST elevation” with “STEMI.” Mechanism‑based learning teaches clinicians to analyze:
- Morphology
- Context
- Stability
- Reciprocal changes
- Clinical presentation
This prevents unnecessary interventions.
Conclusion
This case illustrates how pattern‑based errors lead to unnecessary procedures, while mechanism‑based reasoning leads to accurate diagnosis.
For a curated overview of the most frequent ECG interpretation errors, see: Top 10 ECG Mistakes Clinicians Still Make.