From the Guidelines
The Sgarbossa criteria for diagnosing ST-Elevation Myocardial Infarction (STEMI) in patients with left bundle branch block (LBBB) or ventricular paced rhythm include three ECG findings: ST elevation ≥1mm that is concordant with the QRS complex, ST depression ≥1mm in leads V1-V3, and ST elevation ≥5mm that is discordant with the QRS complex, as reported by Sgarbossa et al in the GUSTO-1 trial 1.
Key Findings
- The original Sgarbossa criteria assign points to each of these findings, with a score of ≥3 points indicating likely acute myocardial infarction.
- The criteria were developed based on the observation that loss of normal QRS complex-T-wave axes discordance in patients with LBBB may imply injury or ischemia.
- The modified Sgarbossa criteria replace the third criterion with a proportional measurement: ST elevation to S-wave ratio ≤-0.25 in leads with discordant ST elevation, which improves diagnostic accuracy.
Clinical Application
- The Sgarbossa criteria help identify patients who need immediate reperfusion therapy despite confounding ECG patterns.
- The criteria work because during acute coronary occlusion, ST segment changes that follow the same direction as the QRS complex (concordant) or that are excessively discordant relative to the QRS amplitude represent true myocardial injury rather than the expected repolarization abnormalities of LBBB or paced rhythm, as noted in the study by Wackers and Hands et al, which demonstrated the sensitivity and specificity of these findings for AMI 1.
Important Considerations
- The Sgarbossa criteria should be applied in the context of clinical suspicion for acute myocardial infarction and other diagnostic findings.
- The criteria are not a replacement for clinical judgment, but rather a tool to aid in the diagnosis of STEMI in patients with LBBB or ventricular paced rhythm.
From the Research
Sgarbossa Criteria for ST-Elevation Myocardial Infarction (STEMI)
The Sgarbossa criteria are used to diagnose STEMI in patients with left bundle branch block (LBBB) on an electrocardiogram (ECG). The criteria include:
- ST elevation ≥ 1 mm in leads with a positive QRS complex
- ST depression ≥ 1 mm in leads V1-V3
- ST elevation ≥ 5 mm in leads with a negative QRS complex 2 These criteria are important for identifying STEMI in patients with LBBB, as the diagnosis can be challenging due to the abnormal ECG pattern.
Importance of Sgarbossa Criteria
The Sgarbossa criteria are significant because they help identify STEMI in patients with LBBB, which is a critical condition that requires prompt treatment. The criteria have been shown to be valuable in diagnosing STEMI in patients with LBBB, and their use can help improve patient outcomes 2.
Limitations of Sgarbossa Criteria
While the Sgarbossa criteria are useful, they have limitations. The criteria may not be sensitive enough to detect all cases of STEMI, and other diagnostic methods, such as coronary angiography, may be necessary to confirm the diagnosis 2. Additionally, the criteria may not be applicable to all patients with LBBB, and other factors, such as the presence of other ECG abnormalities, may need to be considered.
Related Studies
Other studies have investigated the diagnosis and treatment of STEMI, including the use of primary percutaneous coronary intervention (PCI) and fibrinolysis therapy 3, 4, 5, 6. These studies have shown that prompt treatment of STEMI is critical for improving patient outcomes, and that the use of evidence-based guidelines can help optimize care.