An Interesting ECG Case
78-year-old woman with hypertension, diabetes, and a permanent pacemaker calls 911 for increasing shortness of breath and chest pressure for 2 hours. She is pale and diaphoretic. EMS obtains the following ECG:
Can STEMI be diagnosed with a paced rhythm?
Yes, using the Sgarbossa Criteria.
This ECG shows:
• Ventricular paced rhythm (pacing spikes preceding most QRS complexes, wide QRS with LBBB morphology).
• Concordant ST depression ≥1 mm in leads V1-4.
• Sgarbossa criteria are met.
Key Teaching Points
• STEMI can occur in paced rhythms, though detection is more difficult.
• Sgarbossa criteria:
- Concordant ST elevation ≥1 mm in any lead.
- Concordant ST depression ≥1 mm in V1–V3.
- Excessively discordant ST elevation (ST/S ratio > 0.25).
• Any one of the above is suggestive of acute MI.
Sgarbossa Criteria Are Highly Specific but Not Highly Sensitive.
If met, STEMI is likely. If not met, STEMI not ruled out, but likelihood of an occlusive MI lower.
Management
• High clinical suspicion +ve Sgarbossa score supports urgent cath lab activation.
• Serial ECGs and bedside echo may assist in unclear cases.
• Paced rhythms are not a contraindication to reperfusion therapy if STEMI is suspected.
