Modified Sgarbossa Criteria Calculator – STEMI Diagnosis in LBBB

Clinical calculation support · Verify results before clinical use

ECG criteria assessment

Enter J-point ST deviation and predominant QRS direction for each lead.

Not assessedAssessment

Assess a 12-lead ECG in a patient with LBBB or ventricular-paced rhythm. Measurements are in millimeters at standard ECG calibration (25 mm/s, 10 mm/mV). Use the isoelectric baseline and J point consistently.

Measurement convention: Enter ST deviation as a signed value: elevation is positive (e.g., +1.0 mm) and depression is negative (e.g., −1.0 mm). Select the predominant QRS direction. For a lead with a negative QRS and ST elevation ≥1 mm, enter the S-wave depth (positive magnitude, in mm) to calculate the proportional ST/S ratio.

Lead	Predominant QRS	ST deviation (mm)	S-wave depth (mm)
I	Predominant QRS direction in I	ST deviation in millimeters in I	S-wave depth in millimeters in I
II	Predominant QRS direction in II	ST deviation in millimeters in II	S-wave depth in millimeters in II
III	Predominant QRS direction in III	ST deviation in millimeters in III	S-wave depth in millimeters in III
aVR	Predominant QRS direction in aVR	ST deviation in millimeters in aVR	S-wave depth in millimeters in aVR
aVL	Predominant QRS direction in aVL	ST deviation in millimeters in aVL	S-wave depth in millimeters in aVL
aVF	Predominant QRS direction in aVF	ST deviation in millimeters in aVF	S-wave depth in millimeters in aVF
V1	Predominant QRS direction in V1	ST deviation in millimeters in V1	S-wave depth in millimeters in V1
V2	Predominant QRS direction in V2	ST deviation in millimeters in V2	S-wave depth in millimeters in V2
V3	Predominant QRS direction in V3	ST deviation in millimeters in V3	S-wave depth in millimeters in V3
V4	Predominant QRS direction in V4	ST deviation in millimeters in V4	S-wave depth in millimeters in V4
V5	Predominant QRS direction in V5	ST deviation in millimeters in V5	S-wave depth in millimeters in V5
V6	Predominant QRS direction in V6	ST deviation in millimeters in V6	S-wave depth in millimeters in V6

Complete QRS direction and ST deviation for all 12 leads. S-wave depth is required only when a negative-QRS lead has ST elevation ≥1 mm. Leave other S-wave depth fields blank.

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Modified Sgarbossa assessment

Awaiting ECG measurements

Complete the required lead measurements, then select Calculate.

Clinical interpretation

No assessment has been performed.

About the Modified Sgarbossa Criteria

The Modified Sgarbossa Criteria are ECG criteria intended to identify acute coronary occlusion in patients with left bundle branch block (LBBB). The modified rule retains the two concordant ST-segment criteria and replaces the original absolute discordant ST-elevation threshold with a proportional ST/S-wave criterion.

Three diagnostic components

Concordant ST elevation: J-point ST elevation ≥1 mm in a lead with a predominantly positive QRS complex.
Concordant ST depression: J-point ST depression ≥1 mm in any of leads V1–V3 with a predominantly negative QRS complex.
Proportionally excessive discordant ST elevation: ST elevation ≥1 mm in a lead with a predominantly negative QRS complex, with ST elevation/S-wave depth ratio ≤−0.25. The calculator reports the signed ratio as −(ST elevation ÷ S-wave depth).

Decision rule

Any one of the three components being present makes the Modified Sgarbossa Criteria positive. This is a criteria-based rule, not an additive point score. A negative result does not exclude acute coronary occlusion.

Measurement notes

ST deviation is measured at the J point relative to the isoelectric baseline. The S-wave depth is the magnitude from baseline to the S-wave nadir in the same lead. Ensure consistent ECG calibration and measurement technique. If the ECG is technically inadequate or measurements cannot be made reliably, do not interpret an incomplete assessment as negative.

Clinical context and limitations

Interpret the ECG together with symptoms, haemodynamic status, prior ECGs, serial ECGs, biomarkers, bedside imaging where appropriate, and specialist assessment. The rule supports recognition of possible acute coronary occlusion; it does not independently establish myocardial infarction or dictate reperfusion treatment. The 2025 ACC/AHA ACS guideline states that new or presumed-new LBBB alone should not be considered diagnostic of acute MI.

References

Smith SW, Dodd KW, Henry TD, Dvorak DM, Pearce LA.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. DOI: 10.1016/j.annemergmed.2012.07.119.

Meyers HP, Limkakeng AT Jr, Jaffa EJ, et al.Validation of the modified Sgarbossa criteria for acute coronary occlusion in the setting of left bundle branch block: A retrospective case-control study. Am Heart J. 2015;170(6):1255–1264. DOI: 10.1016/j.ahj.2015.09.005.

Dodd KW, Zvosec DL, Hart MA, et al.Electrocardiographic Diagnosis of Acute Coronary Occlusion Myocardial Infarction in Ventricular Paced Rhythm Using the Modified Sgarbossa Criteria. Ann Emerg Med. 2021;78(4):517–529. DOI: 10.1016/j.annemergmed.2021.03.036.

Rao SV, O’Donoghue ML, Ruel M, et al.2025 ACC/AHA/ACEP/NAEMSP/SCAI Guideline for the Management of Patients With Acute Coronary Syndromes. J Am Coll Cardiol. 2025. DOI: 10.1016/j.jacc.2024.11.009.

Sgarbossa EB, Pinski SL, Barbagelata A, et al.Electrocardiographic diagnosis of evolving acute myocardial infarction in the presence of left bundle-branch block. N Engl J Med. 1996;334:481–487. DOI: 10.1056/NEJM199602223340801.

Clinical disclaimer: This calculator is an adjunct for ECG assessment and education. A positive result should prompt urgent clinical evaluation for possible acute coronary occlusion in the appropriate clinical setting. A negative result does not rule out acute coronary occlusion or acute coronary syndrome. Do not delay emergency assessment, serial ECGs, biomarker testing, or specialist consultation when clinically indicated.