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Electrocardiographic ST segment elevation: a comparison of AMI and non-AMI ECG syndromes
William J Brady1, Andrew D Perron, Edward A Ullman
1Department of Emergency Medicine, University of Virginia School of Medicine, Charlottesville, VA, USA.
Insights
ST segment elevation (STE) in chest pain patients is often caused by non-acute myocardial infarction (AMI) syndromes. Differentiating AMI from non-AMI requires considering ECG findings alongside the overall clinical picture.
Area of Science:
- Cardiology
- Emergency Medicine
- Electrocardiography
Background:
- ST segment elevation (STE) on electrocardiograms (ECGs) in emergency department (ED) chest pain (CP) patients can indicate acute myocardial infarction (AMI) or other syndromes.
- Differentiating the cause of STE is critical for timely and appropriate patient management.
Purpose of the Study:
- To compare the electrocardiographic features of STE in patients with AMI versus non-AMI syndromes presenting with chest pain.
- To identify ECG characteristics that may help distinguish between AMI and non-AMI causes of STE.
Main Methods:
- Retrospective comparative review of ECGs from adult CP patients in the ED with STE.
- Analysis of ECG features including STE morphology, anatomic distribution, total STE, and ST segment deviation (STD).
- Diagnosis of AMI based on troponin I levels; non-AMI causes determined by medical record review.
Main Results:
- Non-AMI syndromes accounted for the majority (74%) of STE cases in CP patients.
- Anterior STE was more frequent in non-AMI syndromes.
- Concave STE morphology was more common in non-AMI, while nonconcave STE was more frequent in AMI.
- Total ST segment deviation was significantly greater in AMI patients.
Conclusions:
- Non-AMI causes are more common than AMI in ED chest pain patients with STE.
- ECG findings alone are insufficient for definitive diagnosis; integration with clinical data is essential.
- Specific ECG patterns (morphology, distribution, deviation) aid in differentiating AMI from non-AMI causes of STE.
Abstract:
Chest pain (CP) patients presenting to the ED may manifest electrocardiographic ST segment elevation (STE). AMI (acute myocardial infarction) is a less frequent cause of such abnormality and one of many patterns responsible for ST segment elevation in ED CP patients. We performed a retrospective comparative review of the electrocardiographic features of various STE syndromes, focusing on differences between AMI and non-AMI syndromes. The electrocardiograms (ECGs) of consecutive ED adult CP patients (with 3 serial troponin I determinations) were interpreted by 3 attending emergency physicians. These ECGs with STE represented the study population used for analysis. Various electrocardiographic features such as STE, ST segment depression (STD), STE morphology, anatomic distribution of STE, and the number of leads with STE were recorded; derived values such as total STE, total ST segment deviation, and average STE per lead were calculated. Interobserver reliability concerning STE morphology was determined. AMI was diagnosed by abnormal serum troponin I values (>0.1 mg/dL) followed by a rise and fall of the serum marker; STE diagnoses of non-AMI causes were determined by medical record review. Five hundred ninety-nine CP patients were entered in the study with 212 (35%) individuals showing STE, 55 (26%) with electrocardiographic AMI and 157 (74%) with non-AMI electrocardiographic syndromes. Anatomic location within the AMI group included 32 inferior and inferior variants, 18 anterior and anterior variants, and 5 lateral; non-AMI anatomic locations included 56 inferior and inferior variants, 98 anterior and anterior variants, and 3 lateral; anterior STE occurred significantly more often in non-AMI syndromes. Total STE was 15.3 mm in AMI patients and 7.4 mm in non-AMI patients (P =.0004). The number of leads with STE was not significantly different between the two groups, 3.4 mm in AMI and 4.1 in non-AMI syndromes. ST segment elevation per lead was not significantly different in the 2 groups, 4.4 mm in AMI versus 1.8 mm in non-AMI syndromes. Total ST segment deviation (sum of STE and STD) was significantly greater in AMI syndromes, 17.8 mm in AMI compared with 10.5 mm in non-AMI syndromes (P =.00009). The presence of STD occurred at statistically similar rates in both groups. The morphology of the STE occurred in significantly different rates between AMI and non-AMI patterns, concave more often in non-AMI patterns (P <.00001) and nonconcave more often in AMI (P <.00001). Non-AMI causes of STE account for the majority of electrocardiographic syndromes encountered in ED chest pain patients. These findings alone are not adequate to determine the electrocardiographic cause of the ST segment elevation in chest pain patients. When determining AMI versus non-AMI with the ECG, these various findings should be used in the consideration of the overall clinical picture (history, examination, and electrocardiogram) in chest pain patients with ST segment elevation.