Modified Sgarbossa's Criteria (Smith Modification) for MI in LBBB
Modified version of Sgarbossa criteria using proportional (ratio-based) ST deviation rather than absolute 5 mm threshold for identifying STEMI in LBBB/paced rhythm.
Score interpretation
Score 0–1. Criteria not met. STEMI less likely but not excluded in clinical context.
→ Clinical assessment. Serial ECGs. Troponin monitoring. Cardiology review if high suspicion.
Score 2–4. Indeterminate.
→ Immediate cardiology review. Urgent echocardiogram. Consider emergent angiography if haemodynamically compromised.
Score ≥5. High likelihood of STEMI in LBBB. Sensitivity ~80%, Specificity ~99%.
→ Activate cath lab immediately. Do not delay for troponin result. Dual antiplatelet + anticoagulation. Primary PCI.
Interpretation bands for the Modified Sgarbossa. Apply clinical judgement and local guidance.
References
- 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.
- 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.
Related
Curated clinical cross-links plus same-class fallbacks.
- Alteplase (STEMI Thrombolysis) · Thrombolytic / STEMI
- Streptokinase (STEMI Thrombolysis) · Thrombolytic / STEMI
- Hydrocortisone (Oral Replacement) · Glucocorticoid Replacement
- Morphine (Oral) · Strong Opioid Analgesic — Step 3 WHO Ladder
- Oxycodone · Strong Opioid Analgesic — Step 3 WHO Ladder
- Donanemab (Anti-Amyloid Monoclonal Antibody) · Anti-Amyloid Immunotherapy (IgG1 — Targets Pyroglutamate-Modified Amyloid-β)
- Acute Heart Failure · ESC 2021 Heart Failure Guidelines; NICE NG106
- NSTEMI / Unstable Angina · ESC 2020 NSTEMI Guidelines; NICE NG185
- New-Onset Atrial Fibrillation · ESC 2020 AF Guidelines; NICE NG196
- Hypertensive Emergency · ESC/ESH 2018 Hypertension Guidelines; NICE NG136
- Bradycardia Management · Resuscitation Council UK ABCDE; ESC 2021 Pacing Guidelines
Decision support only — verify against a current formulary, NICE, or your local guideline before clinical use.