High-risk ECG patterns in ACS—Need for guideline revision

doi:10.1016/j.jelectrocard.2013.06.008

Journal of Electrocardiology

Volume 46, Issue 6, November–December 2013, Pages 535-539

https://doi.org/10.1016/j.jelectrocard.2013.06.008 Get rights and content

Abstract

The current guidelines advocate distinct approaches (urgent reperfusion therapy) to patients with suspected acute coronary syndromes (ACS) presenting with ST elevation (STE) versus patients without STE on their electrocardiogram (ECG). This is based on the paradigm that STE represents ongoing transmural ischemia due to an acute occlusion of an epicardial coronary artery whereas the significance of other ECG findings is more contentious. The role of urgent coronary angiography in patients without STE is less clear and initial stabilization with conservative treatment is recommended. However, in some cases the distinction between STEMI and non-STE-ACS is difficult. Acute occlusion of a coronary artery may cause less than the current recommended threshold STE. On the other hand, many patients may have STE secondary to nonischemic etiology. In many patients with non-STE-ACS the coronary artery is not completely occluded at the time of presentation and there are rapid fluctuations in the severity of ischemia and hence, dynamic changes are observed in the ECG. Several ECG patterns associated with particular coronary anatomy and high-risk prognosis have been identified. Patients with ACS presenting with these high-risk patterns should probably be referred for coronary angiography with the possibility of urgent intervention with the goal of prevention of ischemic complications, rather than for immediate myocardial salvage, as in classic STEMI.

Introduction

The current guidelines make a clear distinction in the triage and initial management of patients presenting with symptoms suggestive of acute coronary syndrome (ACS) with and without ST elevation (STE) in their presenting ECG.1., 2. STE is thought to manifest ongoing transmural ischemia due to an acute occlusion of a coronary artery. Emergent reperfusion therapy is indicated to “save” myocardium and limit the ischemic damage. Tremendous effort has been invested to shorten the time from initiation of symptoms (or presentation) to reperfusion. The current guidelines suggest that patients presenting without STE can be initially managed conservatively and coronary angiography can be performed later to prevent reinfarction, but not to save myocardium.

However, many patients presenting with chest pain may have STE secondary to nonischemic etiologies.³ Many classic patterns of nonischemic STE can be easily identified (early repolarization, normal pattern, pericarditis, etc). However, it should be remembered that the magnitude and distribution of these nonischemic STE patterns may dramatically change over time. For example, the magnitude of STE secondary to early repolarization tends to diminish with tachycardia, whereas STE secondary to aneurysm or left bundle branch block may increase with tachycardia. On the other hand, some patients with an acute occlusion of a coronary artery with ongoing ischemia may have borderline STE or no STE at all.² The European guidelines suggest that ongoing suspicion of myocardial ischemia, despite medical therapy, is an indication for emergency coronary angiography, even in patients presenting without STE.²

In theory, patients presenting with STE have ongoing ischemia and ongoing necrosis that should be stopped by emergency revascularization. On the other hand, patients with ACS without STE may show diverse angiographic and clinical findings that may signify incomplete and dynamic occlusions. In many patients, symptoms diminish by the time of presentation. In these patients, the ECG is not expected to show acute ischemic changes or localize the site of coronary thrombus. In such instances, the ECG may show the “footprints” of previous ischemia—(terminal) T-wave inversions with insignificant ST deviation. However, if an ECG is recorded during an episode of active symptoms, dynamic changes indicating ischemia can be detected. Thus, it is crucial to interpret the ECG while knowing the clinical data and especially whether or not the patient was symptomatic when the recording was done. Currently, the severity and/or quality of symptoms cannot be stored in the digital database. Future ECG machines should include a method to enter this information, along with the demographic data when the ECG is recorded.

Several high-risk ECG patterns have been described in patients with non-STE-ACS.⁴ These patterns can be divided into those with ongoing ischemia (that do not result in STE) and those without ongoing ischemia (reperfusion of a culprit lesion with high-risk features) (Table 1):

Section snippets

Tall positive T waves without significant ST deviation

The first sign of acute ischemia is an increase in the amplitude of the T waves. This usually precedes STE. In some patients, STE does not occur and the only manifestation of ischemia is tall, symmetric T waves. It has been suggested that persistent tall T waves without STE is seen in patients with good collateral circulation that “protects” the myocardium.⁵ This pattern may be difficult to diagnose on presentation, as there are wide variations in the amplitude of the T waves and factors other

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Cited by (12)

Sharing and Teaching Electrocardiograms to Minimize Infarction (STEMI): reducing diagnostic time for acute coronary occlusion in the emergency department
2021, American Journal of Emergency Medicine
Citation Excerpt :
In response to this, STEMI-equivalent patterns [18-21] and rules for subtle occlusions [22-25] have been identified. This has led to questioning the current STEMI paradigm [26-28] and a proposed paradigm shift to Occlusion myocardial infarction (OMI). [29-31] However, there is also a concern about unnecessary cath lab activation for patients without culprit lesions. [32-36]
Limits to ST-Elevation Myocardial Infarction (STEMI) criteria may lead to prolonged diagnostic time for acute coronary occlusion. We aimed to reduce ECG-to-Activation (ETA) time through audit and feedback on STEMI-equivalents and subtle occlusions, without increasing Code STEMIs without culprit lesions.
This multi-centre, quality improvement initiative reviewed all Code STEMI patients from the emergency department (ED) over a one-year baseline and one-year intervention period. We measured ETA time, from the first ED ECG to the time a Code STEMI was activated. Our intervention strategy involved a grand rounds presentation and an internal website presenting weekly local challenging cases, along with literature on STEMI-equivalents and subtle occlusions. Our outcome measure was ETA time for culprit lesions, our process measure was website views/visits, and our balancing measure was the percentage of Code STEMIs without culprit lesions.
There were 51 culprit lesions in the baseline period, and 64 in the intervention period. Median ETA declined from 28.0 min (95% confidence interval [CI] 15.0–45.0) to 8.0 min (95%CI 6.0–15.0). The website garnered 70.4 views/week and 27.7 visitors/week in a group of 80 physicians. There was no change in percentage of Code STEMIs without culprit lesions: 28.2% (95%CI 17.8–38.6) to 20.0% (95%CI 11.2–28.8%).
Conclusions
Our novel weekly web-based feedback to all emergency physicians was associated with a reduction in ETA time by 20 min, without increasing Code STEMIs without culprit lesions. Local ECG audit and feedback, guided by ETA as a quality metric for acute coronary occlusion, could be replicated in other settings to improve care.
Using ECG-To-Activation Time to Assess Emergency Physicians’ Diagnostic Time for Acute Coronary Occlusion
2021, Journal of Emergency Medicine
Citation Excerpt :
And third, STEMI criteria miss a significant number of acute coronary occlusions (14–16). This last concern has led to the identification of STEMI-equivalent patterns and the development of rules for subtle occlusion, thereby expanding historical criteria for catheterization laboratory (cath lab) activation (17–22). It has also led to a proposed paradigm shift from STEMI to occlusion myocardial infarction (23).
There is no quality metric for emergency physicians’ diagnostic time for acute coronary occlusion.
We sought to quantify diagnostic time associated with automated interpretation, classic ST-elevation myocardial infarction (STEMI) criteria, STEMI-equivalents, and subtle occlusions, using electrocardiogram (ECG)-to-activation of catheterization laboratory time.
This multicenter retrospective study reviewed all code STEMI patients from the emergency department (ED) with confirmed culprit lesions from January 2016 to December 2018. We measured door-to-ECG (DTE) time and ECG-to-activation (ETA) time. We examined the first ED ECGs to determine whether automated interpretation labeled “STEMI,” and they met classic STEMI criteria, STEMI-equivalents, or rules for subtle occlusion. ECG analysis was performed by two emergency physicians blinded to clinical scenario, automated interpretation, and angiographic outcome.
There were 177 code STEMIs with culprit lesions, with a median DTE time of 9.0 min and a median ETA time of 16.0 min. Automated interpretation labeled 55.4% of first ECGs “STEMI” (ETA 6.5 min) and 44.6% not “STEMI” (ETA 66 min, p < 0.0001). Of first ECGs, 63.8% met classic STEMI criteria (ETA 8.0 min), 8.5% had STEMI-equivalents (ETA 32.0 min, p = 0.0026), 16.4% had subtle occlusions (ETA 89.0 min, p = 0.045), and 11.3% had no diagnostic sign of occlusion (ETA 68.0 min, p = 0.20).
STEMI criteria missed more than one-third of occlusions on first ECG, but most had STEMI-equivalents or rules for subtle occlusion. ETA time can serve as a quality metric for emergency physicians to promote new ECG insights and assess quality improvement initiatives.
A novel method for detecting ST segment elevation myocardial infarction on a 12-lead electrocardiogram with a three-dimensional display
2020, Biomedical Signal Processing and Control
Citation Excerpt :
Therefore, if an abnormality is found in any of the leads, the region of the heart represented by the corresponding ECG lead is identified as the location of infarction. The diagnosis and treatment of MI can be determined by precisely analyzing the measured ECG patterns and identifying changes in ECG features, including Q wave, T wave, and ST segment [10–13]. ECG features used for diagnosing MI are present in different leads of the 12-lead ECG.
Two main factors affect the accurate diagnosis of myocardial infarction (MI). The first is achieving accuracy in extracting electrocardiogram (ECG) time domain features and the second is proper analysis of the entire 12-lead ECG. ECG contains measurement data that reflect cardiac activity. However, accurate extraction of ECG features to identify cardiac abnormalities is affected by noise that can degrade the robustness of feature extraction. Each lead in the 12-lead ECG provides different information that can help diagnose MI. Although analyzing the entire 12-lead ECG improves accuracy, it is very time-consuming. This study aimed to propose a three-dimensional (3D) ECG method for detecting ST-segment elevation MI (STEMI) and to confirm the efficacy of the 3D ECG method.
The leads of the existing 12-lead ECG were categorized into limb lead and chest lead groups and reconstructed them in a 3D format using a 3D display method. We extracted new features from the 3D ECG plane and evaluated their ability to detect STEMI based on new features using the K-nearest neighbor classifier.
The 3D ECG detected STEMI with 96.37% accuracy.
The proposed 3D ECG method can be easily used to read the entire 12-lead ECG even with the naked eye.
This method can detect STEMI by simply using the 3D ECG features, thus eliminating the need to extract features such as the ST segment via complicated calculation processes.
Precordial junctional ST-segment depression with tall symmetric T-waves signifying proximal LAD occlusion, case reports of STEMI equivalence
2016, Journal of Electrocardiology
Citation Excerpt :
The above-described ECG pattern occurs in approximately 2% of patients with anterior infarctions. Among other STEMI equivalents are ST-depression in lead V2, ST-elevation in lateral leads V7–V12, AV-conduction abnormalities in the setting of occluded right coronary artery etc. that also require immediate reperfusion therapy [7–9]. Ambulance staff, emergency physicians, cardiologists and other caregivers involved in STEMI networks should familiarize themselves with these sometimes subtle ECG changes.
Timely reperfusion therapy by means of primary percutaneous coronary intervention (PCI) is the preferred treatment for patients with ST-segment elevation myocardial infarction. A significant number of patients with large acute myocardial infarction, caused by occlusion of an epicardial coronary artery, do not show ST-elevation on the electrocardiogram. Other ECG abnormalities may be present, the so called STEMI-equivalents. One such STEMI equivalent, junctional ST-segment depression followed by tall symmetrical T-waves in the precordial leads, often in combination with slight ST-elevation in lead AVR, has been associated with proximal occlusion of the left anterior descending coronary artery. Recognition of this ECG pattern by ambulance staff, emergency physicians and interventional cardiologists envolved in STEMI networks, is important to ensure timely reperfusion therapy in these patients.
In this paper we present three patients with typical symptoms of acute myocardial infarction and the ECG pattern with slight J-point depression combined with tall, symmetrical T-waves.
Prognostic significance of low QRS voltage on the admission electrocardiogram in acute coronary syndromes
2015, International Journal of Cardiology
Citation Excerpt :
The 12-lead electrocardiogram (ECG) is important for early diagnostic evaluation of acute coronary syndromes (ACS). Specific features of a baseline ECG at time of hospital presentation, such as ST-segment deviation and Q waves, are also recognized to contribute predictive information about short-term and long-term outcomes in both ST-segment elevation myocardial infarction (STEMI) and non-ST-segment elevation ACS (NSTE-ACS) [1–3]. There is practical importance in identifying those patients who are at higher risk of unfavorable outcomes using a widely accessible, rapidly available clinical tool.
To examine the prognostic significance of low QRS voltage in a large contemporary cohort of patients with a broad spectrum of acute coronary syndromes (ACS).
12409 patients with STEMI or NSTE-ACS from the Global Registry of Acute Coronary Events (GRACE) and Canadian ACS I registries were stratified based on the presence of low QRS voltage (< 0.5 mV in all limb leads and < 1.0 mV in all precordial leads) on the admission ECG. We performed multivariable logistic regression to assess the independent association between low voltage and in-hospital and 6-month mortality, and tested for its interaction with ST-segment deviation for these outcomes.
Patients with low voltage (3.2%) had higher GRACE risk scores, rates of prior myocardial infarction, and pathological Q waves, with less prevalent ST-segment deviation and ST-segment depression. They had worse left ventricular function and higher unadjusted rates of in-hospital and 6-month mortality. After adjustment for established prognosticators in the GRACE risk models in multivariable analysis, low voltage was independently associated with higher in-hospital mortality (adjusted OR 1.77, 95% CI 1.13–2.78, P = 0.013) and mortality/re-infarction (adjusted OR 1.42, 95% CI 1.05–1.93, P = 0.023), but not 6-month mortality (adjusted OR 1.25, 95% CI 0.85–1.84, P = 0.27). There was no significant interaction between low voltage and ST-segment deviation for any endpoint (interaction P > 0.10 for all endpoints).
Low QRS voltage was associated with previous myocardial infarction and adverse hemodynamic variables at presentation. After adjusting for other prognosticators, low voltage independently predicted higher in-hospital mortality. This increased risk was not modulated by concomitant ST-segment deviation.
Wellens’ syndrome: Recognizing the risks
2015, Revista Colombiana de Cardiologia
El infarto agudo de miocardio es la principal causa de muerte en el mundo. Las guías de manejo de esta patología indican el estudio invasivo urgente en los casos de infarto con supradesnivel del ST o bloqueo nuevo de rama izquierda. Se han descrito patrones electrocardiográficos, que cuando se presentan en el contexto clínico de angina inestable o infarto, predicen la presencia de obstrucciones coronarias severas que pueden ocasionar la muerte. El reconocimiento de estos patrones es clave para su manejo. Se describe el síndrome de Wellens como parte de estas alteraciones predictoras de riesgo.
Acute myocardial infarction is the leading cause of death worldwide. Dedicated management guidelines indicate urgent invasive study in cases of infarction with ST elevation or new left bundle branch block. Electrocardiographic patterns when present in the clinical setting of unstable angina or myocardial infarction predict the presence of severe coronary disease that can lead to death. The recognition of these patterns is very important to take management decisions. A description of Wellens’ syndrome as part of these high-risk predictors is offered.

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High-risk ECG patterns in ACS—Need for guideline revision

Abstract

Introduction

Section snippets

Tall positive T waves without significant ST deviation

J Electrocardiol

Electrocardiol

Chest

Int J Cardiol

J Electrocardiol

J Am Coll Cardiol

J Electrocardiol