Atypical Electrocardiographic Presentations in Need of Primary Percutaneous Coronary Intervention

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.

Comparing Door-To-Balloon Time between ST-Elevation Myocardial Infarction Electrocardiogram and Its Equivalents

Background: In patients with ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary interventions (pPCI), longer door-to-balloon (DTB) time is known to be associated with an unfavorable outcome. A percentage of patients with acute coronary occlusion present with atypical electrocardiographic (ECG) findings, known as STEMI-equivalents. We investigated whether DTB time for STEMI-equivalent patients was delayed. Methods: This is a retrospective study including patients arriving at an emergency department with the acute coronary syndrome in whom emergent pPCI was performed. ECGs were classified into STEMI and STEMI-equivalent groups. We compared DTB time, with its components, between the groups. We also investigated whether STEMI-equivalent ECG was an independent predictor of DTB time delayed for more than 90 min. Results: A total of 180 patients were included in the present study, and 23 patients (12.8%) presented with STEMI-equivalent ECGs. DTB time was significantly delayed in patients with STEMI-equivalent ECGs (89 (80–122) vs. 81 (70–88) min, p = 0.001). Multivariable logistic regression analysis showed that STEMI-equivalent ECG was an independent predictor of delayed DTB time (odds ratio: 4.692; 95% confidence interval: 1.632–13.490, p = 0.004). Conclusions: DTB time was significantly delayed in patients presenting with STEMI-equivalent ECGs. Prompt recognition of STEMI-equivalent ECGs by emergency physicians and interventional cardiologists might reduce DTB time and lead to a better clinical outcome.

Long-term outcomes in patients with acute myocardial infarction and no ischemic changes on electrocardiogram

BACKGROUND

Acute myocardial infarction (MI) is commonly associated with ischemic abnormalities on electrocardiography (ECG). However, a significant proportion of patients present with no ischemic changes (NIC), and their baseline characteristics and management differ considerably from those with other ECG patterns. In the era of rapid troponin assays, the exact prognostic effects of normal ECGs remain unclear.

OBJECTIVES

This study aimed to compare the outcomes of patients with MI without ischemic changes and those with other ECG patterns.

METHODS

Between 2012 and 2018, 155,073 patients with MI were enrolled in the prospective nationwide Polish Registry of Acute Coronary Syndromes (PL-ACS). The patients were assigned to one of the following groups: NIC, ST-segment elevation (STE), ST-segment depression (STD), T-wave inversion (TWI), and other ST-T abnormalities (STT).

RESULTS

The NIC group accounted for 9.56% of all patients. The in-hospital risk of death was lower in the TWI group than in the NIC group. In the STE, STD, and STT groups, the short-term results were substantially worse. During the 12-month observation period, TWI had the best prognosis. The worst long-term prognoses were associated with STT and STD. The outcomes of the STE and NIC groups were similar (12-month death rate 9.0% vs. 8.7%, respectively; P=0.534), despite the fact STE was an independent predictor of 12-month prognosis.

CONCLUSIONS

The prognosis of patients with MI and NIC is not as favorable as previously thought. Their long-term outcomes were equal to those of the TWI and STE MI groups.

de Winter syndrome, a STEMI-equivalent ECG pattern leading to life-threatening arrhythmia: A case report from a non-cardiac catheterization laboratory hospital

de Winter syndrome is a rare but important electrocardiographic pattern to recognize in patients presenting with chest pain. Under-recognition and delayed revascularization in patients with de Winter syndrome may lead to poor clinical outcomes. Despite increasing evidence of its association with total occlusion of the left anterior descending artery, the role of thrombolysis in the absence of percutaneous coronary intervention is not specifically addressed in recent international guidelines. Herein, we report a case of a 50-year-old gentleman with no known medical illness who presented with excruciating chest pain associated with diaphoresis, nausea, and reduced effort tolerance. Clinical examination revealed a distressed patient with bibasal crepitations with no other significant findings. The first ECG was sinus bradycardia with poor R-wave progression. ECG repeated 6 h later revealed de Winter syndrome. Within minutes, the patient developed sustained pulse ventricular tachycardia requiring synchronized cardioversion. The patient was intubated for impending cardiorespiratory failure. We took the pharmacoinvasive approach. The patient received thrombolytic therapy as percutaneous coronary intervention (PCI) was not available and transferring to the nearest cardiac center was not possible within the therapeutic window. He was then subsequently transferred to the nearest cardiac center post thrombolysis for PCI. We report this case study to highlight the importance of recognizing this STEMI-equivalent ECG pattern in patients presenting with chest pain, and call for randomized control trials to evaluate the effectiveness of thrombolytic therapy as an alternative emergent reperfusion strategy in de Winter syndrome in non-cardiac centers.

A deep learning algorithm for detecting acute myocardial infarction

BACKGROUND

Delayed diagnosis or misdiagnosis of acute myocardial infarction (AMI) is not unusual in daily practice. Since a 12-lead electrocardiogram (ECG) is crucial for the detection of AMI, a systematic algorithm to strengthen ECG interpretation may have important implications for improving diagnosis.

AIMS

We aimed to develop a deep learning model (DLM) as a diagnostic support tool based on a 12-lead electrocardiogram.

METHODS

This retrospective cohort study included 1,051/697 ECGs from 737/287 coronary angiogram (CAG)-validated STEMI/NSTEMI patients and 140,336 ECGs from 76,775 non-AMI patients at the emergency department. The DLM was trained and validated in 80% and 20% of these ECGs. A human-machine competition was conducted. The area under the receiver operating characteristic curve (AUC), sensitivity, and specificity were used to evaluate the performance of the DLM.

RESULTS

The AUC of the DLM for STEMI detection was 0.976 in the human-machine competition, which was significantly better than that of the best physicians. Furthermore, the DLM independently demonstrated sufficient diagnostic capacity for STEMI detection (AUC=0.997; sensitivity, 98.4%; specificity, 96.9%). Regarding NSTEMI detection, the AUC of the combined DLM and conventional cardiac troponin I (cTnI) increased to 0.978, which was better than that of either the DLM (0.877) or cTnI (0.950).

CONCLUSIONS

The DLM may serve as a timely, objective and precise diagnostic decision support tool to assist emergency medical system-based networks and frontline physicians in detecting AMI and subsequently initiating reperfusion therapy.

STEMI Equivalents and Their Incidence during EMS Transport

Objective: The management of patients with ST-elevation myocardial infarction (STEMI) is time-critical, with a focus on early reperfusion to decrease morbidity and mortality. It is imperative that prehospital clinicians recognize STEMI early and initiate transport to hospitals capable of percutaneous coronary intervention (PCI) with a door-to-balloon time of ≤90 minutes. Three patterns have been identified as STEMI equivalents that also likely warrant prompt attention and potentially PCI: Wellens syndrome, De Winter T waves, and aVR ST elevation. The goal of our study was to assess the incidence of these findings in prehospital patients presenting with chest pain. Methods: We conducted a retrospective chart review from a large urban tertiary care emergency department. We reviewed the prehospital ECG, or ECG upon arrival, of 861 patients who were hospitalized and required cardiac catheterization between 4/10/18 and 5/7/19. Patients who had field catheterization lab activation by EMS for STEMI were excluded. If a prehospital ECG was not available for review, the first ECG obtained in the hospital was used as a proxy. Each ECG was screened for aVR elevation, De Winter T waves, and Wellens syndrome. Results: Of 278 charts with prehospital ECGs available, 12 met our criteria for STEMI equivalency (4.4%): 6 Wellens syndrome and 6 aVR STEMI. There were no cases of De Winters T waves. Of 573 charts with no prehospital ECG available, 27 had initial hospital ECGs that met our STEMI equivalent criteria (4.7%): 7 Wellens syndrome and 20 aVR STEMI. Again, there were no cases of De Winters T waves. Conclusions: These preliminary data suggest that there are significant numbers of patients whose prehospital ECG findings do not currently meet criteria for field activation of the cardiac catheterization lab, but who may require prompt catheterization. Further studies are needed to look at outcomes, but these results could support the need for further education of prehospital clinicians regarding recognition of these STEMI equivalents, as well as quality initiatives aimed at decreasing door-to-balloon time for patients with STEMI equivalents.

Total coronary occlusion in non ST elevation myocardial infarction: Time to change our practice?

Based on 12‑lead electrocardiogram (ECG) findings, myocardial infarction (MI) patients are dichotomized to ST-elevation MI (STEMI) and non ST-elevation MI (NSTEMI) in terms of management strategy. NSTEMI patients are increasing in numbers worldwide, among which an approximately 30% are associated with a total occlusion of a coronary artery. This review summarizes recent evidence in epidemiology, clinical, laboratory, ECG and prognostic characteristics of this NSTEMI sub-group. Patients with a diagnosis of NSTEMI and a total occluded coronary artery (TOCA) represent a sub-group of NSTEMI patients with total occlusion of coronary arteries and associated high-risk that are frequently not managed according to a STEMI-like pathway. The present review echoes a call for action in changing our everyday clinical practice. Therefore, we propose a new triage algorithm by which recognition of high-risk features in NSTEMI patients is central in order to identify STEMI 'equivalents' among NSTEMI patients in terms of similar pathology and high-risk who may benefit from immediate invasive strategy (<2 h).

Evaluation of Serum Serotonin as a Biomarker for Myocardial Infarction and Ischemia/Reperfusion Injury

Background: Activated platelets release serotonin during acute myocardial infarction (AMI), aggravating myocardial damage and ischemia/reperfusion (I/R) injury. However, serum serotonin and its potential role as a biomarker for myocardial infarction and I/R injury have not been studied so far. Methods: In this investigator-initiated pilot study, we examined 38 patients with ST-segment myocardial infarction (STEMI). We determined serum serotonin levels prior to percutaneous coronary intervention and 8, 16, and 24 h afterwards. We studied whether serum serotonin was associated with I/R injury assessed by ECG analysis and by analysis of TIMI myocardial perfusion grade (TMP) and myocardial blush grade (MGB). Serum serotonin levels were compared to an age-matched control group consisting of patients admitted to the emergency department for any other reason than STEMI. Results: Serum serotonin levels were not elevated in the myocardial infarction group compared to the control cohort and they did not show any timeline kinetics after STEMI. They were not associated with the severity of coronary artery disease, the outcome of coronary angiography, the extent of I/R injury, or the degree of heart failure. Conclusions: Serum serotonin is not suitable as a biomarker after myocardial infarction and in the assessment of I/R injury.

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.