Common pitfalls in the interpretation of electrocardiograms from patients with acute coronary syndromes with narrow QRS: a consensus report

Why do we keep missing left circumflex artery myocardial infarctions?

BACKGROUND

Diagnosis of left circumflex artery (LCx) myocardial infarctions via 12‑lead electrocardiogram (ECG) has posed a challenge to healthcare professionals for many years.

METHODS AND RESULTS

A retrospective observational study was performed to analyze patients admitted with myocardial infarction. The study used electronic medical records and specific ICD-10 codes to identify eligible patients, resulting in 2032 encounters. After independent adjudication of cardiac biomarkers, coronary angiography, and electrocardiographic changes, a final patient population of 58 encounters with acute occlusion myocardial infarction (OMI) with a culprit LCx lesion was established. OMI was defined as a lesion with either thrombolysis in myocardial infarction flow (TIMI) 0-2 or TIMI 3 with Troponin I > 1 ng/mL (Reference range 0.00-0.03 ng/mL). ECGs of these patients were then independently evaluated and grouped into 8 different classifications based on the presence or absence of ST elevation and/or depression in corresponding leads. ECG patterns and anatomical characteristics (proximal or distal to the first obtuse marginal artery) of the LCx lesions were then correlated. The appropriateness of triage and delay in reperfusion therapy were also assessed. Those with a left dominant or codominant circulation, and with LCx lesions proximal to the first obtuse marginal artery, were more likely to present with no or subtle ST-segment changes that led to delays in reperfusion therapy.

CONCLUSIONS

Patients with left or codominant coronary artery circulation, with OMI proximal to the first obtuse marginal artery, may be less likely to have "classic" findings of ST-segment elevation on ECG due to cancellation forces in the limb leads.

Machine learning for ECG diagnosis and risk stratification of occlusion myocardial infarction

Patients with occlusion myocardial infarction (OMI) and no ST-elevation on presenting electrocardiogram (ECG) are increasing in numbers. These patients have a poor prognosis and would benefit from immediate reperfusion therapy, but, currently, there are no accurate tools to identify them during initial triage. Here we report, to our knowledge, the first observational cohort study to develop machine learning models for the ECG diagnosis of OMI. Using 7,313 consecutive patients from multiple clinical sites, we derived and externally validated an intelligent model that outperformed practicing clinicians and other widely used commercial interpretation systems, substantially boosting both precision and sensitivity. Our derived OMI risk score provided enhanced rule-in and rule-out accuracy relevant to routine care, and, when combined with the clinical judgment of trained emergency personnel, it helped correctly reclassify one in three patients with chest pain. ECG features driving our models were validated by clinical experts, providing plausible mechanistic links to myocardial injury.

Machine Learning for the ECG Diagnosis and Risk Stratification of Occlusion Myocardial Infarction at First Medical Contact

Patients with occlusion myocardial infarction (OMI) and no ST-elevation on presenting ECG are increasing in numbers. These patients have a poor prognosis and would benefit from immediate reperfusion therapy, but we currently have no accurate tools to identify them during initial triage. Herein, we report the first observational cohort study to develop machine learning models for the ECG diagnosis of OMI. Using 7,313 consecutive patients from multiple clinical sites, we derived and externally validated an intelligent model that outperformed practicing clinicians and other widely used commercial interpretation systems, significantly boosting both precision and sensitivity. Our derived OMI risk score provided superior rule-in and rule-out accuracy compared to routine care, and when combined with the clinical judgment of trained emergency personnel, this score helped correctly reclassify one in three patients with chest pain. ECG features driving our models were validated by clinical experts, providing plausible mechanistic links to myocardial injury.

Incorporation of Serial 12-Lead Electrocardiogram With Machine Learning to Augment the Out-of-Hospital Diagnosis of Non-ST Elevation Acute Coronary Syndrome

STUDY OBJECTIVE

Ischemic electrocardiogram (ECG) changes are subtle and transient in patients with suspected non-ST-segment elevation (NSTE)-acute coronary syndrome. However, the out-of-hospital ECG is not routinely used during subsequent evaluation at the emergency department. Therefore, we sought to compare the diagnostic performance of out-of-hospital and ED ECG and evaluate the incremental gain of artificial intelligence-augmented ECG analysis.

METHODS

This prospective observational cohort study recruited patients with out-of-hospital chest pain. We retrieved out-of-hospital-ECG obtained by paramedics in the field and the first ED ECG obtained by nurses during inhospital evaluation. Two independent and blinded reviewers interpreted ECG dyads in mixed order per practice recommendations. Using 179 morphological ECG features, we trained, cross-validated, and tested a random forest classifier to augment non ST-elevation acute coronary syndrome (NSTE-ACS) diagnosis.

RESULTS

Our sample included 2,122 patients (age 59 [16]; 53% women; 44% Black, 13.5% confirmed acute coronary syndrome). The rate of diagnostic ST elevation and ST depression were 5.9% and 16.2% on out-of-hospital-ECG and 6.1% and 12.4% on ED ECG, with ∼40% of changes seen on out-of-hospital-ECG persisting and ∼60% resolving. Using expert interpretation of out-of-hospital-ECG alone gave poor baseline performance with area under the receiver operating characteristic (AUC), sensitivity, and negative predictive values of 0.69, 0.50, and 0.92. Using expert interpretation of serial ECG changes enhanced this performance (AUC 0.80, sensitivity 0.61, and specificity 0.93). Interestingly, augmenting the out-of-hospital-ECG alone with artificial intelligence algorithms boosted its performance (AUC 0.83, sensitivity 0.75, and specificity 0.95), yielding a net reclassification improvement of 29.5% against expert ECG interpretation.

CONCLUSION

In this study, 60% of diagnostic ST changes resolved prior to hospital arrival, making the ED ECG suboptimal for the inhospital evaluation of NSTE-ACS. Using serial ECG changes or incorporating artificial intelligence-augmented analyses would allow correctly reclassifying one in 4 patients with suspected NSTE-ACS.

Emerging ECG methods for acute coronary syndrome detection: Recommendations & future opportunities

Despite being the mainstay for the initial noninvasive assessment of patients with symptomatic coronary artery disease, the 12‑lead ECG remains a suboptimal diagnostic tool for myocardial ischemia detection with only acceptable sensitivity and specificity scores. Although myocardial ischemia affects the configuration of the QRS complex and the STT waveform, current guidelines primarily focus on ST segment amplitude, which constitutes a missed opportunity and may explain the suboptimal diagnostic performance of the ECG. This possible opportunity and the low cost and ease of use of the ECG provide compelling motivation to enhance the diagnostic accuracy of the ECG to ischemia detection. This paper describes numerous computational ECG methods and approaches that have been shown to dramatically increase ECG sensitivity to ischemia detection. Briefly, these emerging approaches can be conceptually grouped into one of the following four approaches: (1) leveraging novel ECG waveform features and signatures indicative of ischemic injury other than the classical ST-T amplitude measures; (2) applying body surface potentials mapping (BSPM)-based approaches to enhance the spatial coverage of the surface ECG to detecting ischemia; (3) developing an inverse ECG solution to reconstruct anatomical models of activation and recovery pathways to detect and localize injury currents; and (4) exploring artificial intelligence (AI)-based techniques to harvest ECG waveform signatures of ischemia. We present recent advances, shortcomings, and future opportunities for each of these emerging ECG methods. Future research should focus on the prospective clinical testing of these approaches to establish clinical utility and to expedite potential translation into clinical practice.

Early ischemic ST-segment and T-wave changes during balloon angioplasty

BACKGROUND

Acute coronary occlusion results in increased T-wave amplitude and ST-segment elevation in the ECG leads facing the ischemic region.

MATERIAL AND METHODS

We performed continuous ECG recording in 34 patients during balloon occlusion of the left anterior descending (LAD), left circumflex (LCx) and right coronary artery (RCA). Delta (Δ) ST and ΔT amplitudes were calculated by subtracting the preinflation values from the values measured during balloon inflation.

RESULTS

Occlusion of the LAD resulted in greater increase in the amplitude of the T wave than of the ST segment in lead V2 (ΔT +3.4 mm, inter-quartile range [IQR] 1-6 mm; ΔST +1.4 mm, 0.5-3 mm). During RCA occlusion, ΔST and ΔT didn't differ significantly. LCx occlusion resulted in significant differences between ΔST and ΔT in all leads, except aVF and V3-V4. In two patients (LCx), we observed a biphasic ST-T response: an initial negative change of the T-wave amplitude was followed by a positive change in leads V1-V2. In leads II, III, aVF and V4-V6, there was an initial positive change, followed by a final negative change towards the end of the occlusion.

CONCLUSION

Continuous 12‑lead ECG recording during balloon occlusion of the LCx resulted in significant differences between the ΔST and ΔT values in all leads except aVF and V3-V4. LAD and RCA occlusion resulted in less evident differences between the ST-segment and T-wave changes. A change in polarity of T-wave changes during balloon occlusion (initial negative and final positive change, or vice versa) proved to be a rare finding.

STEMI: A transitional fossil in MI classification?

An important task in emergency cardiology is distinguishing patients with acute coronary occlusion (ACO), who will benefit from emergent reperfusion therapy, from those without ongoing myocyte loss who can be managed with medical therapy and for whom potentially harmful invasive interventions can be deferred. The electrocardiogram is critical in this process. Although the ST-segment elevation myocardial infarction (STEMI)/non-STEMI paradigm is well-established, with "STEMI" representing ACO, its evidence base is poor, and this can have dire consequences. The universally recommended STEMI criteria do not accurately diagnose ACO; in fact, they miss more than one-fourth of the patients with ACO, and also result in a substantial burden of unnecessary catheterization laboratory activations. We here discuss why we believe it is time to change the current STEMI/non-STEMI paradigm.

The de Winter electrocardiogram pattern in a 52-year-old-male: a case report

BACKGROUND

The 12-lead electrocardiogram (ECG) remains the primary test for diagnosis of acute myocardial infarction (MI) secondary to acute coronary occlusion or near occlusion, with insufficient collateral circulation. Decisions regarding urgent reperfusion are based on whether or not there's new ST-segment elevation. The de Winter ECG pattern is a distinct ECG pattern without any ST-segment elevation, it may be missed by anyone unfamiliar with it.

CASE SUMMARY

We present a case whose chief complaint was severe central chest pain, the patient was diagnosed with acute MI secondary to a culprit lesion in the left anterior descending artery, despite the ECG not meeting standard STEMI criteria. After the ECG's significance was recognized by paramedics, the patient received immediate percutaneous coronary intervention with stenting and was discharged home after a brief hospital admission.

DISCUSSION

In some cases, acute MI presents with ECG features that do not meet the standard criteria for STEMI diagnosis. The de Winter ECG pattern is one such example. This pattern should be immediately recognizable to those responsible for the activation of the catheterization laboratory, physicians, and paramedics included.

Long-term outcome of pre-specified ECG patterns in acute coronary syndrome

BACKGROUND

Long-term outcome of real-life acute coronary syndrome (ACS) patients with selected ECG patterns is not well known.

PURPOSE

To survey the 10-year outcome of pre-specified ECG patterns in ACS patients admitted to a university hospital.

METHODS

A total of 1184 consecutive acute coronary syndrome patients in 2002-2003 were included and followed up for 10 years. The patients were classified into nine pre-specified ECG categories: 1) ST elevation; 2) pathological Q waves without ST elevation; 3) left bundle branch block (LBBB); 4) right bundle branch block (RBBB) 5) left ventricular hypertrophy (LVH) without ST elevation except in leads aVR and/or V₁; 6) global ischemia ECG (ST depression ≥0.5 mm in 6 leads, maximally in leads V_4-5 with inverted T waves and ST elevation ≥0.5 mm in lead aVR); 7) other ST depression and/or T wave inversion; 8) other findings and 9) normal ECG.

RESULTS

Any abnormality in the ECG, especially Q waves, LBBB, LVH and global ischemia, had negative effect on outcome. In age- and gender adjusted Cox regression analysis, pathological Q waves (HR 2.28, 95%CI 1.20-4.32, p = .012), LBBB (HR 3.25, 95%CI 1.65-6.40, p = .001), LVH (HR 2.53, 95%CI 1.29-4.97, p = .007), global ischemia (HR 2.22, 95%CI 1.14-4.31, p = .019) and the combined group of other findings (HR 3.01, 95%CI 1.56-6.09, p = .001) were independently associated with worse outcome.

CONCLUSIONS

During long-term follow-up of ACS patients, LBBB, ECG-LVH, global ischemia, and Q waves were associated with worse outcome than a normal ECG, RBBB, ST elevation or ST depression with or without associated T-wave inversion. LBBB was associated with the highest mortality rates.

Evolutionary de Winter pattern: from de Winter ECG to STEMI-A case report

Background

De Winter pattern is associated with acute occlusion in the left anterior descending coronary artery combined with upsloping ST-segment depression at the J point in leads V₁ through V₆ without ST-segment elevation. The ECG changes in this case were illustrated by an up-sloping ST-segment depression in the V₁ to V₆ leads, followed by tall and symmetrical T waves. Changes from de Winter to ST-segment elevation myocardial infarction (STEMI) are rare.

Case presentation

Our case illustrated an evolutionary de Winter sign that changed to STEMI; the patient underwent cardiac catheterization in time.

Conclusions

Patients who have an electrocardiogram showing de Winter changes may require primary percutaneous coronary intervention. Emergency physicians and cardiologists should not ignore these changes.

The "criminal" artery of de Winter may be the left circumflex artery: A CARE-compliant case report

RATIONALE

De Winter et al first described a new ST-segment elevation myocardial infarction (STEMI)-equivalent pattern associated with acute occlusion of the left anterior descending coronary artery (LAD). Studies show that this pattern has a positive predictive value of 95.2% to 100%. However, some cases of non-STEMI, caused by acute right coronary artery or LAD diagonal branch occlusion, have been reported, which exhibit electrocardiogram (ECG) changes similar to the de Winter pattern. Few cases of de Winter ECG pattern caused by left circumflex artery (LCX) stenosis have been reported.

PATIENT CONCERNS

A 57-year-old man was admitted to the emergency department 12 hours after suffering from oppressive chest pain and diaphoresis. The patient had a history of diabetes and smoking. An initial ECG showed atrial fibrillation, upsloping ST-segment depression at the J point, followed by peaked, positive T waves in leads V2 to V6 and slight ST-segment elevation in lead aVR, with poor R-wave progression. Coronary angiography showed tubular stenosis (up to 95%) of the proximal portion of the LCX.

DIAGNOSIS

LCX stenosis led to a diagnosis of non-STEMI.

INTERVENTIONS

Left coronary artery stenosis was successfully treated with angioplasty and insertion of a drug-eluting stent.

OUTCOMES

The patient's chest pain resolved completely after stent implantation. No myocardial infarction occurred during the 6-month follow-up period.

LESSONS

De Winter ECG pattern cannot be presumed to be associated with LAD stenosis and 18-lead ECG is required to support the identification of the "criminal" artery and to rule out posterior myocardial infarction.

ECG analysis in patients with acute coronary syndrome undergoing invasive management: rationale and design of the electrocardiography sub-study of the MATRIX trial

BACKGROUND

The twelve‑lead electrocardiogram (ECG) has become an essential tool for the diagnosis, risk stratification, and management of patients with acute coronary syndromes (ACS). However, several areas of residual controversies or gaps in evidence exist. Among them, P-wave abnormalities identifying atrial ischemia/infarction are largely neglected in clinical practice, and their diagnostic and prognostic implications remain elusive; the value of ECG to identify the culprit lesion has been investigated, but validated criteria indicating the presence of coronary occlusion in patients without ST-elevation are lacking; finally, which criteria among the multiple proposed, better define pathological Q-waves or success of revascularisation deserve further investigations.

METHODS

The Minimizing Adverse hemorrhagic events via TRansradial access site and systemic Implementation of AngioX (MATRIX) trial was designed to test the impact of bleeding avoidance strategies on ischemic and bleeding outcomes across the whole spectrum of patients with ACS receiving invasive management. The ECG-MATRIX is a pre-specified sub-study of the MATRIX programme which aims at analyzing the clinical value of ECG metrics in 4516 ACS patients (with and without ST-segment elevation in 2212 and 2304 cases, respectively) with matched pre and post-treatment ECGs.

CONCLUSIONS

This study represents a unique opportunity to further investigate the role of ECGs in the diagnosis and risk stratification of ACS patients with or without ST-segment deviation, as well as to assess whether the radial approach and bivalirudin may affect post-treatment ECG metrics and patterns in a large contemporary ACS population.

The de winter electrocardiogram pattern is a transient electrocardiographic phenomenon that presents at the early stage of ST-segment elevation myocardial infarction

BACKGROUND

The de Winter electrocardiogram (EKG) pattern is a novel sign that indicates left anterior descending coronary artery (LAD) occlusion in patients with chest pain. This study aimed to assess the prevalence and clinical characteristics of patients with this pattern.

HYPOTHESIS

The de Winter EKG pattern is an special anterior ST-segment elevation myocardial infarction (STEMI) equivalents without obvious ST-segment elevation.

METHODS

This retrospective study included all patients with anterior myocardial infarction admitted between January 2011 and December 2017. Patients were categorized into two groups: those with the de Winter EKG pattern and those with typical STEMI.

RESULTS

Of 441 patients, 15 (3.4%) with anterior myocardial infarction had the de Winter EKG pattern. Similar to those with typical STEMI, the majority of patients with the de Winter EKG pattern had ST-segment elevation, pathologic Q wave, and absence of R wave at follow-up. The median time from recognition of this pattern until its evolution was 114 minutes. The ST-segment in leads V3R to V5R and leads V7 to V9 were normal or slightly depressed when a typical de Winter EKG pattern was noted in leads V1 to V6. The culprit lesion was mainly in the proximal LAD or the diagonal branch. Patients with this EKG pattern responded poorly to thrombolytic therapy.

CONCLUSIONS

We believe that the de Winter EKG pattern may be a sign of ischemia and presents at the early stage of STEMI rather than being an independent pattern. In patients with this pattern, a percutaneous coronary intervention rather than follow-up and thrombolytic strategy should be performed.

New Insights Into the Use of the 12-Lead Electrocardiogram for Diagnosing Acute Myocardial Infarction in the Emergency Department

The 12-lead electrocardiogram (ECG) remains the most immediately accessible and widely used initial diagnostic tool for guiding management in patients with suspected myocardial infarction (MI). Although the development of high-sensitivity cardiac troponin assays has improved the rule-in and rule-out and risk stratification of acute MI without ST elevation, the immediate management of the subset of acute MI with acute coronary occlusion depends on integrating clinical presentation and ECG findings. Careful interpretation of the ECG might yield subtle features suggestive of ischemia that might facilitate more rapid triage of patients with subtle acute coronary occlusion or, conversely, in identification of ST-elevation MI mimics (pseudo ST-elevation MI patterns). Our goal in this review article is to consider recent advances in the use of the ECG to diagnose coronary occlusion MIs, including the application of rules that allow MI to be diagnosed on the basis of atypical ECG manifestations. Such rules include the modified Sgarbossa criteria allowing identification of acute MI in left bundle branch block or ventricular pacing, the 3- and 4-variable formula to differentiate normal ST elevation (formerly called early repolarization) from subtle ECG signs of left anterior descending coronary artery occlusion, the differentiation of ST elevation of left ventricular aneurysm from that of acute anterior MI, and the use of lead aVL in the recognition of inferior MI. Improved use of the ECG is essential to improving the diagnosis and appropriate early management of acute coronary occlusion MIs, which will lead to improved outcomes for patients who present with acute coronary syndrome.

Electrocardiographic findings during balloon angioplasty of the left circumflex coronary artery - influence of location of the ischemic segments with respect to the obtuse margin of the left ventricle

BACKGROUND

Acute left circumflex coronary artery (LCx) occlusion is not easily detected by the standard 12-lead electrocardiogram (ECG).

METHODS

In 16 patients continuous ECG recording was performed during balloon occlusion. The treated lesions were divided into proximal and distal based on the location of the ischemic segments with respect to the left obtuse margin of the heart.

RESULTS

Mean ΔST (=ST amplitude during inflation - pre-inflation ST) ≥0.5mm in both leads I and aVL predicted a proximal occlusion site with sensitivity of 62.5% (95% confidence interval [CI] 24.9-91.5%), specificity 100% (95% CI 63.1-100%), positive predictive value 100% (95% CI 47.8-100%), and negative predictive value 72.7% (95% CI 39-94%). In lead III, mean ΔST was +0.3mm in the distal and -0.2mm in the proximal group, respectively (p=0.036).

CONCLUSIONS

ST elevation in leads I and aVL is associated with myocardial ischemia at or proximal to the left obtuse margin.

A patient with non-ST-segment elevation acute coronary syndrome: Is it possible to predict the culprit coronary artery?

In acute coronary syndromes without ST-segment elevation (NSTE-ACS), identification of the culprit artery is, most often, not possible. In this case report, we elaborate on the likelihood of different culprit arteries in a patient with NSTE-ACS. While her symptoms were progressing, typical ECG findings of ischemia in the left coronary territories were diminishing. Instead, dynamic T-wave changes in the inferior leads were present and were most likely postischemic and "reischemic." Although the culprit artery could not be identified with certainty by means of these subtle changes, they correlated well with the findings on angiography and the ECG recorded afterward. This case report demonstrates the importance of analyzing ECG and its temporal changes in conjunction with evolving symptoms.

Prevalence and Clinical Significance of Up-Sloping ST-Segment Depression in Patients With Non-ST-Segment Elevation Myocardial Infarction

Background

Up-sloping ST-segment depression has not been historically considered as representing ischemia as this electrocardiographic change can be seen in normal subjects during exercise stress testing or tachycardia. We aimed to clarify the prevalence and clinical significance of up-sloping ST-segment depression in patients with non-ST-segment elevation myocardial infarction (NSTEMI).

Methods

We performed a retrospective analysis of 330 consecutive patients with NSTEMI who underwent coronary angiography. ST-segment depression ≥ 0.05 mV in more than two contiguous leads was recorded and categorized as being up-sloping or non-up-sloping.

Results

Of 330 patients, 109 patients (33%) had ST-segment depression; six of these patients had up-sloping ST-segment depression. All six patients with up-sloping ST-segment depression had a culprit lesion and underwent in-hospital revascularization. Three of these six patients had a culprit lesion in the left anterior descending artery; the culprit lesion in two others was in the left circumflex artery, while one patient had severe three-vessel disease. No statistically significant difference was found in the rate of in-hospital revascularization between patients with up-sloping and non-up-sloping ST-segment depression (100% vs. 75%, P = 0.33).

Conclusions

Patients with up-sloping ST-segment depression had a comparable rate of in-hospital revascularization compared to those with non-up-sloping ST-segment depression, suggesting that up-sloping ST-segment depression should be recognized as a manifestation of ischemia in NSTEMI.

The role of the ECG in diagnosis, risk estimation, and catheterization laboratory activation in patients with acute coronary syndromes: a consensus document

The electrocardiogram (ECG) is the most widely used imaging tool helping in diagnosis and initial management of patients presenting with symptoms compatible with acute coronary syndrome. Acute ischemia affects the configuration of the QRS complexes, the ST segments and the T waves. The ECG should be read along with the clinical assessment of the patient. ST segment elevation (and ST depression in leads V1 -V3 ) in patients with active symptoms usually indicates acute occlusion of an epicardial artery with ongoing transmural ischemia. These patients should be triaged for emergent reperfusion therapy per current guidelines. However, many patients have ST segment elevation secondary to nonischemic causes. ST depression in leads other than V1 -V3 usually are indicative of subendocardial ischemia secondary to subocclusion of the epicardial artery, distal embolization to small arteries or spasm supply/demand mismatch. ST depression may also be secondary to nonischemic etiologies, such as left ventricular hypertrophy, cardiomyopathies, etc. Knowing the clinical scenario, comparison to previous ECG and subsequent ECGs (in cases that there are changes in the quality or severity of symptoms) may add in the diagnosis and interpretation in difficult cases. This review addresses the different ECG patterns, typically seen in patients with active symptoms, after resolution of symptoms and the significance of such changes when seen in asymptomatic patients.

Incidence, angiographic features and outcomes of patients presenting with subtle ST-elevation myocardial infarction

BACKGROUND

Borderline electrocardiograms represent a challenge in ST-segment elevation myocardial infarction (STEMI) management and are associated with inappropriate discharges and delays to intervention.

OBJECTIVES

To assess angiographic characteristics and outcomes of patients presenting with subtle ST-elevation (STE) myocardial infarction.

METHODS

A total of 504 consecutive patients with suspected STEMI treated by systematic primary percutaneous coronary intervention were prospectively included. Subtle STE was defined as a maximal preinterventional STE of 0.1 to 1 mm. Angiograms were interpreted by investigators unaware of the electrocardiographic data.

RESULTS

The proportion of patients with subtle STE was 18.3%, 86% of them presented with Thrombolysis In Myocardial Infarction flow grade 0/1 and 91% underwent percutaneous coronary intervention. Despite having smaller infarcts, subtle STE patients associated more frequent multivessel disease (57% vs 44%, P = .02) and larger delays to reperfusion. During a follow-up of 19.0 ± 4.9 months, the rates of death or reinfarction were similar among groups (10.0% vs 12.6%, P = .467). Subtle STE was not associated with better outcomes neither in univariate nor after adjustment in a multivariate analysis (adjusted hazard ratio 0.79, 95% CI 0.37-1.69, P = .546).

CONCLUSIONS

Subtle STEMI is frequent in clinical practice and is usually associated with acute total coronary occlusion. Therefore, it should be diagnosed and treated in the same expeditiously manner as marked STEMI.

Updated electrocardiographic classification of acute coronary syndromes

The electrocardiogram (ECG) findings in acute coronary syndrome should always be interpreted in the context of the clinical findings and symptoms of the patient, when these data are available. It is important to acknowledge the dynamic nature of ECG changes in acute coronary syndrome. The ECG pattern changes over time and may be different if recorded when the patient is symptomatic or after symptoms have resolved. Temporal changes are most striking in cases of ST-elevation myocardial infarction. With the emerging concept of acute reperfusion therapy, the concept ST-elevation/ non-ST elevation has replaced the traditional division into Q-wave/non-Q wave in the classification of acute coronary syndrome in the acute phase.

KEYPOINTS

In acute coronary syndrome, in addition to the traditional electrocardiographic risk markers, such as ST depression, the 12-lead ECG contains additional, important diagnostic and prognostic information. Clinical guidelines need to acknowledge certain high-risk ECG patterns to improve patient care.

Difficult ECGs in STEMI: lessons learned from serial sampling of pre- and in-hospital ECGs

Prehospital interpretation of electrocardiograms (ECGs) is crucial to ensure early diagnosis and optimal treatment of patients with ST elevation myocardial infarction (STEMI). Recognition of ST-segment elevations (STE) by qualified personnel in the prehospital phase has successfully reduced the delay from the first medical contact to reperfusion. A few other ECG patterns without true STE, referred to as "STEMI equivalents", bear the same prognostic significance, reflect imminent or ongoing transmural ischemia, but are less easily identified. Hyperacute T waves, de Winter ST-T complex, Wellens' syndrome, and posterior STEMI, as well as myocardial infarction in the presence of left bundle branch block, paced rhythm or left ventricular hypertrophy, among others are diagnostic challenges. This article reviews some critical examples of ischemic ECG patterns that may be ephemeral, misinterpreted by medical staff or not identified by automated ECG algorithms, and it emphasizes the importance of serial ECG acquisition.

Correlation between ST-segment elevation and negative T waves in the precordial leads in acute pulmonary embolism: insights into serial electrocardiogram changes

BACKGROUND

Acute pulmonary embolism (APE) is often misdiagnosed as acute coronary syndrome because of the similarity of the presenting symptoms and of the electrocardiogram (ECG) manifestations. In APE, ST-segment elevation (STE) in leads V1 to V3 /V4 , mimicking anteroseptal myocardial infarction, is not a rare phenomenon. Negative T waves (NTW) in the precordial leads mimicking the "Wellens' syndrome" is an important ECG manifestation of APE. The evolution of these ECG changes-STE and NTW-in APE has not been thoroughly studied.

METHODS

We present two patient cases with APE and their evolving serial ECGs to analyze the correlation between STE and NTW.

RESULTS

NTW developed later than STE in these two patient cases.

CONCLUSIONS

NTW might represent a "postischemic" ECG pattern indicating a previous stage with transmural myocardial ischemia.

A new ST-segment elevation myocardial infarction equivalent pattern? Prominent T wave and J-point depression in the precordial leads associated with ST-segment elevation in lead aVr

Certain acute coronary syndrome electrocardiographic (ECG) patterns, which do not include ST-segment elevation, are indicative of acute coronary syndrome caused by significant arterial occlusion; these patterns are, of course, associated with significant risk to the patient and mandate a rapid response from the health care team. One such high-risk ECG pattern includes the association of the prominent T wave and J-point depression producing ST-segment depression seen in the precordial leads coupled with ST-segment elevation in lead aVr. This ECG presentation is associated with significant left anterior descending artery obstruction. We report the case of a patient with this ECG presentation who progressed over a very short time to ST-segment elevation myocardial infarction of the anterior wall.