Sgarbossa Criteria for MI in LBBB
Identifies STEMI in the presence of left bundle branch block (LBBB) using 3 ECG criteria. Modified Sgarbossa uses proportional ST/S ratio ≥ 0.25 instead of absolute ≥1mm concordance.
Score interpretation
Score < 3: Does not meet Sgarbossa criteria. MI in LBBB less likely but not excluded.
→ Clinical correlation essential. Serial ECGs and troponins. If high clinical suspicion for ACS, treat empirically and arrange urgent cardiology review / cath lab activation per local STEMI-equivalent protocol.
Score 3 (concordant ST depression criterion only): Possible STEMI-equivalent.
→ Urgent cardiology/senior review. Serial ECGs, troponins, echo. Low threshold for cath lab activation. Dual antiplatelet, anticoagulation per ACS protocol.
Score ≥ 5 (concordant ST elevation present): High specificity for MI. Treat as STEMI-equivalent.
→ Activate cath lab immediately. Dual antiplatelet (aspirin + P2Y12 inhibitor). Anticoagulation. Contact interventional cardiology. Door-to-balloon < 90 minutes target.
Interpretation bands for the Sgarbossa. Apply clinical judgement and local guidance.
References
- Sgarbossa EB, et al. Electrocardiographic diagnosis of evolving acute myocardial infarction in the presence of left bundle-branch block. N Engl J Med. 1996;334(8):481–487.
- Smith SW, et al. Diagnosis of ST-elevation myocardial infarction in the presence of left bundle branch block with the ST-elevation to S-wave ratio in a modified Sgarbossa rule. Ann Emerg Med. 2012;60(6):766–776.
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Curated clinical cross-links plus same-class fallbacks.
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Decision support only — verify against a current formulary, NICE, or your local guideline before clinical use.