Interpretation of acute myocardial infarction with persistent 'hyperacute T waves' by cardiac magnetic resonance

An unusual cause of giant T waves

In the acute care setting, the two most common causes of giant upright T waves include hyperkalemia and the very early phase of acute myocardial infarction (MI). The former is characterized by narrow based and peaked T waves. The giant T waves of early MI, also called "hyperacute T waves," are usually more broad-based. The general recommendation is to consider hyperacute T waves a form of occlusion MI, and to proceed with emergent cardiac catheterization and revascularization. In this report, we present the case of a young man with cocaine toxicity and status epilepticus where the initial electrocardiogram (ECG) demonstrated giant T waves. Both hyperkalemia and coronary occlusion were ruled out. Within a few hours, the ECG spontaneously normalized. Review of the literature revealed that although uncommon, acute cerebral events including seizures can cause transient giant T waves. When giant T waves are noted in association with a cerebral event, emergent cardiac catheterization may not be warranted.

De Winter's ECG: Not your usual STEMI

We report a 39-year-old male who presented with severe chest pain and diaphoresis who suffered from pulseless polymorphic ventricular tachycardia en route to the hospital. His initial electrocardiogram showed De Winter's Pattern (dWP). Coronary angiography revealed 100% thrombotic ostial occlusion of the left anterior descending artery. In young males presenting with chest pain and diaphoresis, dWP should be part of a clinician's differential diagnosis when analyzing the initial electrocardiogram. The medical community needs increased awareness to prevent delay of revascularization because dWP is an ST-segment elevation myocardial infarction (STEMI) equivalent and does not present like a typical STEMI on electrocardiogram.

Clinical outcomes in acute coronary syndrome after presentation of unique electrocardiographic findings

BACKGROUND

Unique electrocardiographic findings are rarely observed in acute coronary syndrome (ACS) with a culprit left anterior coronary artery (LAD). The aim of this study was to assess the epidemiological features and prognostic impact.

METHODS

This study was designed as an observational study. A total of 641 patients with a culprit lesion in the left main trunk or LAD were extracted from a cohort of 1776 ACS patients. The primary endpoint was mortality, comparing patients presenting with unique electrocardiogram patterns, specifically the de Winter pattern or Wellens' syndrome (type A or B), upon hospital arrival, with those presenting common electrocardiogram patterns.

RESULTS

A unique electrocardiogram was observed in 7.0% (n = 45; 2 with de Winter pattern, 14 with Wellens' type A and 29 with type B). Compared to patients with a common pattern, cardiogenic shock at hospital arrival were rare in patients with a unique pattern (0% vs. 8.4%, P = 0.04), and percutaneous coronary intervention was primary revascularization strategy in all groups (95.6% vs. 98.2%). The mortality rates were similar between the two groups over a median 565 days of observation period (13.3% vs. 15.7%, P = 0.43), with 0% in Wellens' type A, 13.8% in type B, and both patients with the de Winter pattern died.

CONCLUSION

The de Winter pattern or the Wellens syndrome was found in 7.0% of cases with ACS. They had similar mortality rates compared to those with a common pattern, although the de Winter pattern was identified in only 2 patients.

Context-independent identification of myocardial ischemia in the prehospital ECG of chest pain patients

Non-traumatic chest pain is a frequent reason for an urgent ambulance visit of a patient by the emergency medical services (EMS). Chest pain (or chest pain-equivalent symptoms) can be innocent, but it can also signal an acute form of severe pathology that may require prompt intervention. One of these pathologies is cardiac ischemia, resulting from a disbalance between blood supply and demand. One cause of a diminished blood supply to the heart is acute coronary syndrome (ACS, i.e., cardiac ischemia caused by a reduced blood supply to myocardial tissue due to plaque instability and thrombus formation in a coronary artery). ACS is dangerous due to the unpredictable process that drives the supply problem and the high chance of fast hemodynamic deterioration (i.e., cardiogenic shock, ventricular fibrillation). This is why an ECG is made at first medical contact in most chest pain patients to include or exclude ischemia as the cause of their complaints. For speedy and adequate triaging and treatment, immediate assessment of this prehospital ECG is necessary, still during the ambulance ride. Human diagnostic efforts supported by automated interpretation algorithms seek to answer questions regarding the urgency level, the decision if and towards which healthcare facility the patient should be transported, and the indicated acute treatment and further diagnostics after arrival in the healthcare facility. In the case of an ACS, a catheter intervention room may be activated during the ambulance ride to facilitate the earliest possible in-hospital treatment. Prehospital ECG assessment and the subsequent triaging decisions are complex because chest pain is not uniquely associated with ACS. The differential diagnosis includes other cardiac, pulmonary, vascular, gastrointestinal, orthopedic, and psychological conditions. Some of these conditions may also involve ECG abnormalities. In practice, only a limited fraction (order of magnitude 10%) of the patients who are urgently transported to the hospital because of chest pain are ACS patients. Given the relatively low prevalence of ACS in this patient mix, the specificity of the diagnostic ECG algorithms should be relatively high to prevent overtreatment and overflow of intervention facilities. On the other hand, only a sufficiently high sensitivity warrants adequate therapy when needed. Here, we review how the prehospital ECG can contribute to identifying the presence of myocardial ischemia in chest pain patients. We discuss the various mechanisms of myocardial ischemia and infarction, the typical patient mix of chest pain patients, the shortcomings of the ST-elevation myocardial infarction (STEMI) and non-ST-elevation myocardial infarction (NSTEMI) ECG criteria to detect a completely occluded culprit artery, the OMI ECG criteria (including the STEMI-equivalent ECG patterns) in detecting completely occluded culprit arteries, and the promise of neural networks in recognizing ECG patterns that represent complete occlusions. We also discuss the relevance of detecting any ACS/ischemia, not necessarily caused by a total occlusion, in the prehospital ECG. In addition, we discuss how serial prehospital ECGs can contribute to ischemia diagnosis. Finally, we discuss the diagnostic contribution of a serial comparison of the prehospital ECG with a previously made nonischemic ECG of the patient.

Uncommon Culprit Vessel of de Winter Electrocardiogram Pattern

This case report describes a patient in their 50s who presented to the emergency department with perspiration, persistent and squeezing chest pain, and chest distress that had persisted for 90 minutes without relief.

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.

The Role of ECG in the Diagnosis and Risk Stratification of Acute Coronary Syndromes: an Old but Indispensable Tool

PURPOSE OF REVIEW

Since its inception in 1902 by Willem Einthoven, the electrocardiogram (ECG) has fundamentally undergone minimal technological advances. Nevertheless, its clinical utility is critical, and it remains an essential tool to diagnose, risk stratify, and guide reperfusion and invasive strategies in patients with suspected acute coronary syndromes. ECG reading can be demanding, with many healthcare professionals lacking the necessary expertise to accurately interpret them. This is exacerbated by the need to constantly revisit old dogmas pertinent to the interpretation of ECGs.

RECENT FINDINGS

Notably, ECG leads record the global electrical activity of the heart toward and away from each electrode rather than local events. The long-held central paradigm that the various ECG leads record local events underneath specific electrodes should therefore be reassessed. For example, ST segment elevation in leads V1 and V2 usually denote antero-apical rather than septal infarction, often a misnomer utilized by the majority of clinicians. The ECG diagnosis of ST-elevation myocardial infarction (STEMI) is sometimes challenging and discerning it from non-ST-elevation myocardial infarction (NSTEMI) is of paramount importance to implement timely acute reperfusion therapy. In fact, when qualifications for emergency reperfusion therapy are based on STEMI ECG criteria, nearly one-third of cases with acute coronary occlusion are missed. Diagnostic ST elevation in the absence of left ventricular (LV) hypertrophy or left bundle-branch block (LBBB) is defined by a specific set of sex-specific criteria for new ST elevation at the J point in contiguous precordial or limb leads. However, other ECG criteria need to be kept in mind. These include, but are not limited to, new or presumably new left bundle branch block (LBBB), which is often considered as an STEMI-equivalent; ST depression in two or more precordial leads (V1-V4), denoting a true inferolateral transmural myocardial infarction; and the infrequent presentation with hyperacute T-wave changes. As our understanding of the pathology of ischemic reperfusion injury has evolved and following the introduction of new imaging modalities such as cardiac magnetic resonance imaging, we need to re-assess the old dogmas pertinent to the interpretation of ECGs and update the terms and classifications.

The de Winter ECG pattern: Distribution and morphology of ST depression

Background

The reported positive predictive value (PPV) for the “de Winter ECG pattern” to predict an acute left anterior descending artery (LAD) lesion is inconsistent. Besides, the morphology of upsloping or nonupsloping ST depression (STD) may have different significance of severity and prognostication.

Methods

We searched the MEDLINE database using “de Winter” or “junctional ST‐depression with tall symmetrical T‐waves” or “tall T wave” or “STEMI equivalent” as the item up to March 2020. We compared the ECG differences between the different culprit arteries and various morphological STD.

Results

A total of 70 patients with analyzable ECGs were included. In 60 patients (LAD group), the LAD was the culprit artery, while in 10 patients (non‐LAD group), there were other etiologies. Maximal STD in V2 or V3 had a PPV of 89% of all patients and 98% of patients without ST elevation in V2 to detect an acute LAD lesion. The presence of q/Q‐wave or poor R‐wave progression in the precordial leads was significantly more often found in patients with upsloping STD than in patients with nonupsloping STD in the LAD group (84% vs. 27%, p < .01). In 18 patients, the ECG showed a change from upsloping to nonupsloping STD from the leads with maximal STD to the surrounding leads with less STD.

Conclusions

The location of the maximal STD in the precordial leads differs between patients with LAD as the culprit artery and other etiologies of the de Winter ECG pattern. Upsloping STD signifies more severe signs of ischemia than nonupsloping STD.

Atypical Electrocardiographic Presentations in Need of Primary Percutaneous Coronary Intervention

Early initiation of reperfusion therapy remains the cornerstone of successful management for ST-elevation myocardial infarction (STEMI). Rapid restoration of coronary blood flow relies on prompt recognition of the typical ST-segment elevation on a 12-lead electrocardiogram (ECG)-a surrogate for coronary occlusion or critical stenosis-allowing timely activation of the STEMI protocol cascade, with a major positive impact in mortality and clinical outcomes. However, atypical, very high risk ECG patterns-known as "STEMI equivalents"-are present in 10% to 25% of patients with ongoing myocardial ischemia in need of urgent primary percutaneous coronary intervention. Though briefly mentioned in the current recommendations, structured clinical data on those specific ECG presentations are lacking. By thoroughly searching MEDLINE and EMBASE we conducted a structured review of non-STEMI, albeit very high risk, ECG patterns of acute coronary syndrome, often associated with coronary occlusion or critical stenosis. After screening 997 studies, we identified the following distinct "STEMI equivalent" ECG patterns: Wellens' syndrome, de Winter sign, hyperacute T waves, left bundle branch block-including paced rhythm-and right bundle branch block. For each pattern, a brief summary of the existing evidence, together with the sensitivity, specificity, and positive predictive value-whenever available-are presented. In conclusion, prompt recognition of "STEMI equivalent" ECG patterns is crucial for every physician or paramedic dealing with acute coronary syndrome patients in the emergency department or the prehospital setting, as misinterpretation of those high risk presentations can lead to reperfusion delays and worse outcomes.

The De Winter ECG pattern: morphology and accuracy for diagnosing acute coronary occlusion: systematic review

The De Winter ECG pattern has been reported to indicate acute left anterior descending coronary artery occlusion and is often considered to be an 'ST elevation myocardial infarction (STEMI) equivalent'. We aimed to investigate the morphology of the 'De Winter ECG pattern' and evaluate the test characteristics of the De Winter pattern for the diagnosis of acute coronary occlusion. We identified papers through the Medline, EMBASE and COCHRANE databases and screened for bias using QUADAS-2. First, measurements were recorded from every ECG reported in the literature and aggregated. Second, diagnostic accuracy data from eligible cohort studies were extracted. The primary outcome was defined as at least 70% angiographic stenosis of a major epicardial vessel. Thirteen papers reported data relevant to question 1 and three papers reported data relevant to question 2. All ECGs showed maximal up-sloping ST depression in lead V3 with a median amplitude of 0.3 mV (interquartile range: 0.2-4 mV). T-wave height peaked in lead V3 with a median amplitude 0.9 mV (interquartile range: 0.8-1.1 mV). The De Winter pattern had positive predictive values of 95.2% (95% confidence interval: 76.2-99.9%), 100% (69.2-100.0%) and 100% (51.7-100%) in the three respective diagnostic studies. There is limited evidence that the De Winter ECG pattern is a 'STEMI equivalent'. The available data suggest that the pattern has high positive predictive value for acute occlusion. Further research is required to evaluate specificity and to determine whether rapid revascularization improves mortality.