ECG can be used to triage patients who require urgent or emergent cardiac electrophysiology procedures when they present to the emergency department with signs of an arrhythmia or the need for an adjustment to a cardiovascular implantable electronic device (CIED) like a pacemaker or a change in QT due to a drug to control arrhythmia.
Guidance issued in 2020 by the Heart Rhythm Society, the American College of Cardiology, and the American Heart Association (HRS/ACC/AHA) notes that more than 40% of cardiology encounters are related to arrhythmia.1 This finding highlights the importance of ECG and the need for electrophysiologists on the care team.
Defining Urgent and Emergent Procedures
According to the HRS/ACC/AHA authors, procedures are deemed urgent or emergent if they have a major impact on reducing risks of clinical decompensation, hospitalization, or death. Procedures that fit this definition include cardioversion for highly symptomatic atrial arrhythmias or drug refractory rapid ventricular rates, as well as transesophageal echocardiography prior to an urgent cardioversion. Catheter ablation is also urgent in the following scenarios:
- Ventricular tachycardia (VT) ablation for an electrical storm unresponsive to medical therapy in a patient with hemodynamic compromise
- Afib, atrial flutter, or atrioventricular nodal ablation if the arrhythmias are hemodynamically significant, severely symptomatic, and unresponsive to antiarrhythmic drugs, rate control, and cardioversion
- Wolff-Parkinson-White (WPW) syndrome or preexcited Afib with syncope or cardiac arrest
Several CIED-related situations are also considered urgent or emergent:
- Lead revision driven by malfunction in an ICD or pacemaker-dependent patient who is receiving inappropriate therapy
- Generator change in a pacemaker-dependent patient with an elective replacement indicator or at the end of the device's life, or for a device with minimal battery remaining
- Implantation of a secondary prevention ICD
- Implantation of a pacemaker for symptomatic complete heart block, Mobitz II or high-grade atrioventricular block, or severely symptomatic sinus node dysfunction with long pauses
- Lead/device extraction for infection, including endocarditis, bacteremia, or pocket infection
- Cardiac resynchronization therapy for severe refractory heart failure
Similar guidance from the Latin American Heart Rhythm Society lists additional procedures considered emergent or semi-urgent, such as catheter ablation for incessant VT refractory to drugs, recurrent VT leading to multiple hospitalizations or ICD shocks, and paroxysmal Afib/atrial flutter or recurrent supraventricular tachycardia requiring frequent hospitalizations.2
How ECG Can Help
A collection of patient scenarios in the Journal of Emergencies, Trauma, and Shock identified several instances when emergency catheter ablation would be warranted in critically ill patients. These include WPW syndrome with a risk of sudden cardiac death, incessant VT related to ischemic cardiomyopathic shock, electrical storm in an ICD patient, and idiopathic VF.3
One case in particular highlights the key role of ECG in the triage of cardiac electrophysiology procedures. In that case, a 31-year-old woman developed syncope and stopped breathing. After her husband resuscitated her, she was taken to the emergency department, where she was diagnosed with ventricular fibrillation (VF). Defibrillation restored normal rhythm.
After 3 days of intensive care, a 12-lead ECG revealed preexcitation syndrome "with a suspected accessory pathway at the inferoseptal aspect," the authors report. The patient was taken to another center for catheter ablation of the accessory pathway, which was successful. She did not have an ICD implanted at that point because there was no family history of cardiac arrest, normal echocardiographic findings, and no abnormalities on a 12-lead ECG performed after ablation.
In another case series published in EP Europace, urgent radiofrequency catheter ablation was performed in patients with acute decompensated heart failure after sustained ventricular tachyarrhythmias were detected by 12-lead surface ECG.4 The procedure completely suppressed sustained VT/VF in 80% of patients, and acute heart failure was resolved in 93% of patients.
To learn more about the power of the ECG in today's clinical landscape, browse our Diagnostic ECG Clinical Insights Center.
How AI Assists with Clinical Judgment
It's possible that developments in artificial intelligence (AI) will enhance ECG's vital role in the emergency department in triaging patients for urgent or emergent cardiac electrophysiology procedures.
A study in the Journal of the American Heart Association evaluated automatic triage of 12-lead ECGs taken at the University Medical Center in Utrecht, the Netherlands using deep convolutional neural networks.5 The approach showed "excellent overall discrimination" in classifying ECGs into categories based on how quickly a cardiologist should be consulted to review the findings. The authors proposed that this development "could lead to improved time to treatment for acute cardiac disorders and decreased and better‐balanced workloads for clinicians."
The ECG should not drive medical decisions in isolation, however. ECG readings should be considered in tandem with other factors like patient age, presenting complaints, physical exam findings, and results of other diagnostic tests.6 While an ECG can aid differential diagnosis, predict complications, and help a clinician stratify risks or choose a therapy, all of these paths require strong clinical judgement and an awareness of ECG's limitations.
1. Lakkireddy DR, Chung MK, Gopinathannair R, et al. Guidance for cardiac electrophysiology during the COVID-19 pandemic from the Heart Rhythm Society COVID-19 Task Force; Electrophysiology Section of the American College of Cardiology; and the Electrocardiography and Arrhythmias Committee of the Council on Clinical Cardiology, American Heart Association. Heart Rhythm. March 2020; 141: e823-e831. https://www.ahajournals.org/doi/full/10.1161/CIRCULATIONAHA.120.047063
2. Saenz LC, Miranda A, Speranza R, et al. Recommendations for the organization of electrophysiology and cardiac pacing services during the COVID-19 pandemic. Journal of Interventional Cardiac Electrophysiology. April 2020; 59: 307-313. https://link.springer.com/article/10.1007/s10840-020-00747-5
3. Tebbenjohanns J, Ruhmkorf K. Emergency catheter ablation in critical patients. Journal of Emergencies, Trauma, and Shock. March 2010; 3(2): 160-163. https://www.onlinejets.org/article.asp?issn=0974-2700;year=2010;volume=3;issue=2;spage=160;epage=163;aulast=Tebbenjohanns
4. Hayashi M, Miyauchi Y, Murata H, et al. Urgent catheter ablation for sustained ventricular tachyarrhythmias in patients with acute heart failure decompensation. EP Europace. January 2014; 16(1): 92-100. https://academic.oup.com/europace/article/16/1/92/463871
5. Van de Leur RR, Blom LJ, Gavves E, et al. Automatic triage of 12-lead ECGs using deep convolutional neural networks. Journal of the American Heart Association. May 2020; 9(10): e015138. https://www.ahajournals.org/doi/full/10.1161/JAHA.119.015138
6. Brady WJ, Tabas JA, Mattu A. The ECG and clinical decision-making in the emergency department. In: Mattu A, Tabas J, Brady W, eds. Electrocardiography in Emergency, Acute, and Critical Care. 2nd ed. American College of Emergency Physicians; 2019:1-13. Accessed April 27, 2022. https://bookstore.acep.org/img/product/description/ECG%202e%20Chapter%201.pdf