Prehospital 12-Lead Electrocardiogram within 60 Minutes Differentiates Proximal versus Nonproximal Left Anterior
Robert A Aertker1, Colin M Barker, H Vernon Anderson
1University of Texas at Houston Medical School, Department of Internal Medicine-Division of Cardiology, Houston, Texas.
Insights
A 12-lead electrocardiogram (ECG) can predict proximal left anterior descending (LAD) artery occlusions within the first hour of symptom onset. This finding helps identify high-risk ST-elevation myocardial infarctions (STEMI) for prompt transfer to PCI-capable hospitals.
Area of Science:
- Cardiology
- Medical Diagnostics
- Emergency Medicine
Background:
- Acute anterior myocardial infarctions from proximal LAD occlusions carry high morbidity and mortality.
- Early identification of high-risk STEMI patients is crucial for timely intervention.
- Limited PCI-capable hospitals necessitate efficient patient routing.
Purpose of the Study:
- To determine if the 12-lead ECG can predict proximal LAD artery occlusions.
- To identify high-risk STEMI patients for potential prehospital routing.
Main Methods:
- Retrospective analysis of the Pre-Hospital Administration of Thrombolytic Therapy with Urgent Culprit Artery Revascularization pilot trial.
- Compared ECG findings in patients with proximal vs. nonproximal LAD occlusions within 180 minutes of symptom onset.
Main Results:
- Within 60 minutes of symptom onset, a sum of ST elevation (STE) in leads V1-V6 plus ST depression (STD) in leads II, III, and aVF of ≥17.5 mm predicted proximal LAD occlusions with 92.9% specificity.
- This ECG pattern showed a positive predictive value of 91.7% for proximal LAD occlusions.
- No significant difference in ST-segment deviation was observed when ECGs were performed >60 minutes after symptom onset.
Conclusions:
- The sum STE (V1-V6) and STD (II, III, aVF) on a 12-lead ECG can predict proximal LAD occlusions within the first hour of symptom onset.
- This ECG finding signifies a high-risk condition.
- Prehospital identification can prompt direct transfer of STEMI patients to PCI-capable facilities.
Introduction:
Acute anterior myocardial infarctions caused by proximal left anterior descending (LAD) artery occlusions are associated with a higher morbidity and mortality. Early identification of high-risk patients via the 12-lead electrocardiogram (ECG) could assist physicians and emergency response teams in providing early and aggressive care for patients with anterior ST-elevation myocardial infarctions (STEMI). Approximately 25% of US hospitals have primary percutaneous coronary intervention (PCI) capability for the treatment of acute myocardial infarctions. Given the paucity of hospitals capable of PCI, early identification of more severe myocardial infarction may prompt emergency medical service routing of these patients to PCI-capable hospitals. We sought to determine if the 12 lead ECG is capable of predicting proximal LAD artery occlusions.
Methods:
In a retrospective, post-hoc analysis of the Pre-Hospital Administration of Thrombolytic Therapy with Urgent Culprit Artery Revascularization pilot trial, we compared the ECG findings of proximal and nonproximal LAD occlusions for patients who had undergone an ECG within 180 minutes of symptom onset.
Results:
In this study, 72 patients had anterior STEMIs, with ECGs performed within 180 minutes of symptom onset. In patients who had undergone ECGs within 60 minutes (n = 35), the mean sum of ST elevation (STE) in leads V1 through V6 plus ST depression (STD) in leads II, III, and aVF was 19.2 mm for proximal LAD occlusions and 11.7 mm for nonproximal LAD occlusions (P = 0.007). A sum STE in V1 through V6 plus STD in II, III, and aVF of at least 17.5 mm had a sensitivity of 52.3%, specificity of 92.9%, positive predictive value of 91.7%, and negative predictive value of 56.5% for proximal LAD occlusions. When the ECG was performed more than 60 minutes after symptom onset (n = 37), there was no significant difference in ST-segment deviation between the 2 groups.
Conclusion:
The sum STE (V1-V6) and STD (II, III, aVF) on a 12-lead ECG can be used to predict proximal LAD occlusions if performed within the first hour of symptom onset. This should be considered a high-risk finding and may prompt prehospital direction of such patients to PCI-capable hospitals.
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