From the Guidelines
Sgarbossa's criteria are a valuable diagnostic tool for identifying acute myocardial infarction (AMI) in patients with left bundle branch block (LBBB), with a high specificity of 92% for ST-segment elevation of 1 mm or more concordant with the QRS complex, as reported by Sgarbossa et al in the GUSTO-1 trial 1. The criteria include three key findings:
- ST-segment elevation of 1 mm or more concordant with the QRS complex,
- ST-segment depression of 1 mm or more concordant with the QRS in one or more precordial leads V1 through V3, and
- ST-segment elevation of 5 mm or more in discordant leads. These criteria are particularly important because LBBB causes secondary ST-T changes that can mimic or mask AMI, and traditional ECG criteria for STEMI are unreliable in LBBB patients. The sensitivity and specificity of these findings for AMI were reported as 73% and 92% for ST-segment elevation, 25% and 96% for ST-segment depression, and 19% and 82% for ST-segment elevation in discordant leads, respectively 1. When using these criteria, it's essential to consider them alongside clinical presentation, cardiac biomarkers, and other diagnostic modalities for optimal patient management in suspected AMI with LBBB. Some studies have reported on the predictive value of these criteria, including Wackers, who found a sensitivity, specificity, and positive predictive value of 54%, 97%, and 96%, respectively, for ST-segment changes in patients with LBBB and suspected AMI 1. However, the study by Sgarbossa et al in the GUSTO-1 trial remains the most relevant and highest quality study on this topic, providing the best evidence for the diagnostic value of Sgarbossa's criteria in patients with LBBB 1.
From the Research
Diagnostic Value of Sgarbossa's Criteria
The diagnostic value of Sgarbossa's criteria for acute myocardial infarction (AMI) in the presence of a left bundle branch block (LBBB) is a topic of interest in the medical field.
- The criteria have been evaluated in several studies, with varying results 2, 3, 4, 5, 6.
- A study published in 2019 found that ECG criteria, including Sgarbossa's criteria, had low sensitivity (1%-12%) but high specificity (95%-100%) for AMI in patients with LBBB 2.
- Another study published in 2013 found that a Sgarbossa score of ≥3 had a superb specificity (98%) and positive predictive value for acute myocardial infarction and angiography-confirmed acute coronary occlusion 3.
- A 2012 study found that replacing the absolute ST-elevation measurement of ≥5 mm in the third component of the Sgarbossa rule with an ST/S ratio less than -0.25 greatly improved the diagnostic utility of the rule for STEMI equivalent 4.
- A 2020 study introduced a new electrocardiographic algorithm, the BARCELONA algorithm, which was derived and validated to diagnose AMI in patients with LBBB, and found it to be highly sensitive and specific 5.
- A 2008 meta-analysis found that a Sgarbossa ECG algorithm score of ≥3 was useful for diagnosing acute myocardial infarction in patients who present with left bundle branch block on ECG, with a summary sensitivity of 20% and specificity of 98% 6.
Predictive Value
- The predictive value of Sgarbossa's criteria is influenced by the score, with a score of ≥3 being more specific and having a higher positive predictive value 3, 6.
- The criteria can be used in combination with other diagnostic tools, such as high-sensitivity cardiac troponin (hs-cTn) testing, to improve diagnostic accuracy 2.
- The BARCELONA algorithm has been shown to be highly sensitive and specific for diagnosing AMI in patients with LBBB, and may be a useful alternative to Sgarbossa's criteria 5.