Comparison of EASI-derived 12-lead electrocardiograms versus paramedic-acquired 12-lead electrocardiograms using Mason-Likar limb lead configuration in patients with chest pain

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.

Telemedicine in the Era of a Pandemic: Usefulness of a Novel Three-Lead ECG

The 12-lead electrocardiogram (ECG) is a first-line diagnostic tool for patients with cardiac symptoms. As observed during the COVID-19 pandemic, the ECG is essential to the initial patient evaluation. The novel KardioPal three-lead-based ECG reconstructive technology provides a potential alternative to a standard ECG, reducing the response time and cost of treatment and improving patient comfort. Our study aimed to evaluate the diagnostic accuracy of a reconstructed 12-lead ECG obtained by the KardioPal technology, comparing it with the standard 12-lead ECG, and to assess the feasibility and time required to obtain a reconstructed ECG in a real-life scenario. A prospective, nonrandomized, single-center, adjudicator-blinded trial was conducted on 102 patients during the COVID-19 pandemic at the Dedinje Cardiovascular Institute in Belgrade. The KardioPal system demonstrated a high feasibility rate (99%), with high specificity (96.3%), sensitivity (95.8%), and diagnostic accuracy (96.1%) for obtaining clinically relevant matching of reconstructed 12-lead compared to the standard 12-lead ECG recording. This novel technology provided a significant reduction in ECG acquisition time and the need for personnel and space for obtaining ECG recordings, thereby reducing the risk of viral transmission and the burden on an already overwhelmed healthcare system such as the one experienced during the COVID-19 pandemic.

Left arm/left leg lead reversals at the cable junction box: A cause for an epidemic of errors

Medical errors, especially due to misinterpretation of electrocardiograms (ECG), are extremely common in patients admitted to the hospital and significantly account for increased morbidity, mortality and health care costs in the United States. Inaccurate performance of an ECG can lead to invalid interpretation and in turn may lead to costly cardiovascular evaluation. We report a retrospective series of 58 sequential cases of ECG limb lead reversals in the ER due to inadvertent interchange in the lead cables at the point where they insert into the cable junction box of one ECG machine. This case series highlights recognition of ECG lead reversal originating in the ECG machine itself. This case series also demonstrates an ongoing need for education regarding standardization of ECG testing and for recognizing technical anomalies to deliver appropriate care for the patient.

Transtelephonic electrocardiographic transmission in the preparticipation screening of athletes

Transtelephonic electrocardiographic transmission (TET) is the most widespread form of telecardiology since it enables clinicians to assess patients at a distance. The purpose of this study was to assess the efficacy and effectiveness of TET either by fixed telephone line (POTS) or by mobile phone in the preparticipation screening of young athletes. A total of 506 players, aged 20.5 ± 6.2 years, from 23 soccer clubs in the prefecture of Thessaloniki, Greece, were physically examined in their playfields by a general practitioner (GP) and had their ECG recorded. In 142 cases, and on the judgment of the GP, the ECG was transmitted via POTS and/or global system for mobile communications (GSM) to a specialised medical centre where it was evaluated by a cardiologist. The mean total time for recording, storing, and transmitting the ECG was four minutes per subject. It was found that the success rate for transmission at first attempt was similar for both fixed and mobile networks, that is, 93% and 91%, respectively. The failure rate in the GSM network was correlated to the reception level at the site of transmission. Only in about half (n = 74) of the transmitted ECGs did the cardiologist confirm “abnormal” findings, although in 16, they were considered to be clinically insignificant. Consequently, 58 athletes were referred for further medical examination. Our results indicate that TET (either by fixed telephone line or by mobile phone) can ensure valid, reliable, and objective measurements, and significantly contribute to the application of medical screening in a great number of athletes. Therefore, it is recommended as an alternative diagnostic tool for the preparticipation screening of athletes living in remote areas.

Technical mistakes during the acquisition of the electrocardiogram

In addition to knowledge of normal and pathological patterns, the correct interpretation of electrocardiographic (ECG) recordings requires the use of acquisition procedures according to approved standards. Most manuals on standard electrocardiography devote little attention to inadequate ECG recordings. In this article, we present the most frequent ECG patterns resulting from errors in limb and precordial lead placement, artifacts in 12-lead ECG as well as inadequate filter application; we also review alternative systems to the standard ECG, which may help minimize errors.

Comparison of p-wave patterns derived from correct and incorrect placement of V1-V2 electrodes

BACKGROUND AND RESEARCH OBJECTIVE

Precordial electrode misplacement is an important source of error in electrocardiogram (ECG) interpretation. Previous studies have shown important changes affecting P wave morphology when V1 and V2 electrodes are placed in higher intercostal spaces. We aimed to identify ECG signs that could alert professionals performing or interpreting the ECG about the incorrect placement of V1 and V2 electrodes.

SUBJECTS AND METHODS

This cross-sectional study included 101 apparently healthy individuals. Five P wave patterns were compared, placing electrodes V1 and V2 on the fourth (correct position), third, and second intercostal spaces (incorrect position).

RESULTS

Incorrect V1-V2 electrode placement produced statistically significant differences in 3 of 5 ECG patterns. The presence of a negative component of the P wave in V2 (P < .001), negative P wave in V1 (P < .001), and rSr' preceded by negative P wave (P < .001) was strongly indicative of high placement. Patterns where the amplitude ratio between the positive and negative components of the P wave in V1 was less than or equal to 1 were observed in 27 of 101 cases with correct placement. However, on comparing correct and incorrect electrode placement, significant differences were found (P < .001)

CONCLUSION

Patterns that indicate high placement of V1 and V2 were (1) negative component of the P wave in V2 lead recorded in either second and third intercostal spaces, (2) negative P wave in V1 lead recorded in either second and third intercostal spaces, and (3) rSr' preceded by negative P wave recorded only when V1 is placed on the second but not on the third intercostal space.

Where do derived precordial leads fail?

A 12-lead electrocardiogram (ECG) reconstructed from a reduced subset of leads is desired in continued arrhythmia and ST monitoring for less tangled wires and increased patient comfort. However, the impact of reconstructed 12-lead lead ECG on clinical ECG diagnosis has not been studied thoroughly. This study compares the differences between recorded and reconstructed 12-lead diagnostic ECG interpretation with 2 commonly used configurations: reconstruct precordial leads V(2), V(3), V(5), and V(6) from V(1),V(4), or reconstruct V(1), V(3), V(4), and V(6) from V(2),V(5). Limb leads are recorded in both configurations. A total of 1785 ECGs were randomly selected from a large database of 50,000 ECGs consecutively collected from 2 teaching hospitals. ECGs with extreme artifact and paced rhythm were excluded. Manual ECG annotations by 2 cardiologists were categorized and used in testing. The Philips resting 12-lead ECG algorithm was used to generate computer measurements and interpretations for comparison. Results were compared for both arrhythmia and morphology categories with high prevalence interpretations including atrial fibrillation, anterior myocardial infarct, right bundle-branch block, left bundle-branch block, left atrial enlargement, and left ventricular hypertrophy. Sensitivity and specificity were calculated for each reconstruction configuration in these arrhythmia and morphology categories. Compared to recorded 12-leads, the V(2),V(5) lead configuration shows weakness in interpretations where V(1) is important such as atrial arrhythmia, atrial enlargement, and bundle-branch blocks. The V(1),V(4) lead configuration shows a decreased sensitivity in detection of anterior myocardial infarct, left bundle-branch block (LBBB), and left ventricular hypertrophy (LVH). In conclusion, reconstructed precordial leads are not equivalent to recorded leads for clinical ECG diagnoses especially in ECGs presenting rhythm and morphology abnormalities. In addition, significant accuracy reduction in ECG interpretation is not strongly correlated with waveform differences between reconstructed and recorded 12-lead ECGs.

Detection of acute ischemia from the EASI-derived 12-lead electrocardiogram and from the 12-lead electrocardiogram acquired in clinical practice

ST-segment measurements in the standard 12-lead electrocardiogram (ECG) of patients with acute coronary syndromes are crucial for these patients' management. Our objective was to determine whether the 12-lead ECG derived from the 3-lead EASI system can attain a level of diagnostic performance similar to that of the Mason-Likar (ML) 12-lead ECG acquired in clinical practice (CP) by paramedics and emergency department technicians. Using 120-lead body surface potential maps recorded before and during balloon inflation angioplasty from 88 patients (divided into "responders" and "nonresponders"), and electrode placement data from 60 applications of precordial leads in CP, we generated for the "nonischemic" and "ischemic" states of each patient the following lead sets: the ML 12-lead ECG, the EASI-derived 12-lead ECG, and 60 sets of 12-lead CP ECGs. We extracted ST deviations at J + 60 milliseconds, summed them for all 12 leads of each lead set to obtain SigmaST, and, by using the bootstrap method, determined the mean sensitivity and specificity for recognizing the "ischemic" state at various thresholds of SigmaST. Results were displayed as receiver operating characteristics, and the area under these curves (AUC) +/- SE was used as the measure of diagnostic performance. AUC +/- SE for all patients were ML ECG, 0.66 +/- 0.03; EASI ECG, 0.64 +/- 0.03; and CP ECG, 0.67 +/- 0.03. Corresponding results for responders only were 0.81 +/- 0.04 for ML ECG, 0.78 +/- 0.04 for EASI ECG, and 0.81 +/- 0.04 for CP ECG. The differences between the AUCs for the different lead sets were not significant (P > .05). Thus, the EASI-derived 12-lead ECG is as good for detecting acute ischemia as is the 12-lead ECG acquired in CP.