What are the Cornell criteria used for in diagnosing acute myocardial infarction (AMI) in patients with left bundle branch block (LBBB)?

Cornell Criteria for Diagnosing AMI in LBBB

The term "Cornell criteria" does not exist in the medical literature for diagnosing acute myocardial infarction in patients with left bundle branch block—you are likely referring to the Sgarbossa criteria, which are the validated ECG criteria used for this purpose. 1

The Sgarbossa Criteria

The Sgarbossa criteria were developed from the GUSTO-I trial and consist of three weighted ECG findings that help identify AMI in the presence of LBBB 1:

Primary Criteria (High Specificity)

• ST-segment elevation ≥1 mm concordant with the QRS complex (same direction as the major QRS deflection)

  • Sensitivity: 73%, Specificity: 92% 1
  • This is the most reliable single criterion 1

• ST-segment depression ≥1 mm in leads V1-V3 (concordant with predominantly negative QRS)

  • Sensitivity: 25%, Specificity: 96% 1

• ST-segment elevation ≥5 mm discordant from the QRS complex (opposite direction from major QRS deflection)

  • Sensitivity: 19%, Specificity: 82% 1
  • Note: This criterion has lower specificity and recent evidence suggests it may have very low diagnostic utility 1

Scoring System

A Sgarbossa score ≥3 points indicates high likelihood of AMI 2:

• Concordant ST elevation ≥1 mm = 5 points
• Concordant ST depression ≥1 mm in V1-V3 = 3 points
• Discordant ST elevation ≥5 mm = 2 points

Patients with scores ≥3 have significantly higher 30-day mortality (23.5% vs 7.7%) compared to those with scores <3 2.

Clinical Application Algorithm

Step 1: Initial Assessment

• Obtain 12-lead ECG within 10 minutes of first medical contact 1, 3
• Recognize that LBBB occurs in only 2.8% of patients with suspected ACS, and only 30% of these will have AMI 4

Step 2: Apply Sgarbossa Criteria

• Look specifically for concordant ST elevation ≥1 mm (highest specificity >90%) 1, 3
• Check for concordant ST depression in V1-V3 1
• Do not rely on discordant ST changes alone as they have poor diagnostic accuracy 1

Step 3: Integrate with Troponin Testing

• Combine ECG criteria with high-sensitivity troponin at 0/1 hour or 0/2 hours for optimal diagnostic accuracy (AUC 0.89-0.91) 4
• This combined approach identifies 97-100% of AMI cases in LBBB 4

Step 4: Management Decision

• If Sgarbossa criteria are met OR high clinical suspicion persists despite negative criteria, proceed immediately to emergency coronary angiography with intent for primary PCI 1, 3
• Target first medical contact-to-device time ≤90 minutes 1, 3
• If PCI unavailable and symptom onset <3 hours, consider fibrinolytic therapy 3

Critical Pitfalls to Avoid

Do not assume new LBBB equals AMI 1, 3:

• New or presumably new LBBB should NOT be considered diagnostic of AMI in isolation 1
• Clinical correlation is mandatory 1
• Most LBBB patients in the ED do not have acute coronary occlusion 1

Do not withhold evaluation based on negative Sgarbossa criteria 5:

• ECG criteria have low sensitivity (1-12%) but high specificity (95-100%) 4
• Treating all LBBB patients with chest pain would result in unnecessary treatment of many without AMI 5
• Serial ECGs should be performed when clinical suspicion remains high 1, 3

Do not forget to obtain comparison ECG 1:

• A previous ECG showing pre-existing LBBB significantly aids interpretation 1

Modified Sgarbossa Criteria

Recent research suggests using proportional discordance (ST elevation ≥25% of the depth of the preceding S-wave) may improve sensitivity while maintaining specificity 6, though this has not been validated in ventricular pacing and is not yet incorporated into major guidelines 6.