What is the Sgarbossa criteria used for?

The Sgarbossa criteria are a set of three ECG findings that help identify acute myocardial infarction (MI) in patients with left bundle branch block (LBBB) or a ventricular paced rhythm, where the standard ST-elevation criteria cannot be applied.

What score is diagnostic for acute MI?

A total score of 3 or more points is considered the threshold with high specificity (specificity ~90%) for acute MI. However, even a score below 3 does not rule out MI — clinical judgment and serial ECGs remain essential.

What is the modified Sgarbossa (Smith) criteria?

The modified criteria replace criterion 3 (≥5 mm discordant ST elevation) with a proportional ST deviation rule: ST/S ratio ≤ −0.25 in any lead. This improves sensitivity while maintaining specificity, as validated by Smith et al.

Does a negative score rule out MI?

No. Sgarbossa criteria have moderate sensitivity. A score below 3 does not exclude MI. Continue with troponin testing, repeat ECGs, and clinical evaluation when suspicion remains.

Can this tool be used for right bundle branch block (RBBB)?

No. Sgarbossa criteria were developed and validated specifically for LBBB and ventricular paced rhythms. Different diagnostic considerations apply for RBBB.

Sgarbossa Criteria Calculator

Score ECG findings with the Sgarbossa criteria to identify acute MI in the presence of LBBB or paced rhythm.

Original Sgarbossa Criteria

Select all ECG findings present on the patient's tracing.

Concordant ST elevation ≥ 1 mm

ST segment rises in the same direction as the QRS complex — 5 points

Concordant ST depression ≥ 1 mm in V1–V3

ST segment falls with a predominantly negative QRS in leads V1–V3 — 3 points

Discordant ST elevation ≥ 5 mm (Original criterion 3)

Excessively discordant ST elevation ≥ 5 mm where QRS is negative — 2 points

Modified Criterion 3 (Smith-Sgarbossa)

Replaces the fixed ≥ 5 mm threshold with a proportional ratio for higher sensitivity.

ST/S Ratio (enter a negative value, e.g. −0.30)

≤ −0.25 = positive

Leave blank to use original criterion 3 points from the checkbox above.

Result

Select criteria and click Calculate.

Quick Reference

Score	Interpretation	Specificity
≥ 5	High suspicion for acute MI	~98%
3–4	Moderate suspicion — consider cath lab activation	~90%
1–2	Low specificity, MI not excluded	~52%
0	Criteria not met — low but non-zero risk	—

Summary

The Sgarbossa criteria provide a validated scoring system for diagnosing acute myocardial infarction when left bundle branch block (LBBB) or a ventricular paced rhythm is present. Each ECG finding is weighted and the total score guides clinical suspicion. A score of 3 or more carries high specificity for MI, and the modified Smith-Sgarbossa criteria use proportional ST changes for improved sensitivity.

How it works

Assess the patient's ECG for each of the three Sgarbossa criteria findings.
Select the checkboxes corresponding to the ST changes observed on the ECG.
The calculator assigns points (5, 3, or 2) per criterion as originally validated.
For the modified criteria, enter the ST/S amplitude ratio if applicable.
Review the total score and the plain-language interpretation provided.
A score ≥ 3 has high specificity for acute MI; clinical context is always required.

Use cases

Emergency physicians evaluating LBBB with chest pain for acute STEMI equivalents.
Paramedics running prehospital 12-lead ECG on pacemaker-dependent patients.
Cardiology fellows learning to apply and interpret Sgarbossa criteria at the bedside.
Medical educators demonstrating the difference between original and modified scoring.
Quality assurance reviews of missed MI cases in patients with LBBB.
Rapid bedside decision support when cath lab activation is being considered.

Frequently Asked Questions

Last updated: 2026-06-11 · Reviewed by Nham Vu