Abstract
Focal atrial tachycardia arising from the right atrial appendage (RAAT) may be misdiagnosed as sinus tachycardia. The electrocardiogram from this case demonstrates a negative notched P-wave in leads V1 and V2 during RAAT compared with a beat of sinus rhythm. RAAT was confirmed and eliminated with mapping and ablation. (Level of Difficulty: Advanced.)
Key Words: ablation, P-wave morphology, right atrial appendage tachycardia
Abbreviations and Acronyms: AT, atrial tachycardia; ECG, electrocardiogram; IEGM, intracardiac electrogram; RA, right atrium; RAAT, right atrial appendage atrial tachycardia
Central Illustration
Case
A 23-year-old woman presented with palpitations that began at age 17 years. They occurred intermittently, lasted up to 30 minutes several times throughout the day and night, were worse with activity, and also woke her up at night. Her pulse would go up to 150 beats/min on her watch, sometimes with associated dizziness. Echocardiography revealed a structurally normal heart (ejection fraction: 57%). Her resting electrocardiogram (ECG) is shown in Figure 1.
Figure 1.
Electrocardiogram
Patient’s resting electrocardiogram in clinic.
WHAT IS THE DIAGNOSIS?
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A.
Premature atrial complexes
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B.
Right atrial appendage atrial tachycardia (RAAT)
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C.
Postural orthostatic tachycardia syndrome
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D.
Inappropriate sinus tachycardia
The correct answer is B.
Explanation
This ECG demonstrates focal RAAT, with spontaneous termination and a single sinus beat (Supplemental Figure 1, dot), followed by resumption of RAAT (Supplemental Figure 1, arrow). The 12-lead ECG can provide accurate localization of focal atrial tachycardias (ATs) with high sensitivity and specificity (1). However, the ECG of RAAT often appears similar to sinus rhythm because of the close proximity of the RAA and the sinus node in the high right atrium (RA). Both RAAT and sinus rhythm typically have positive P waves in the inferior leads and a positive precordial transition by lead V3. During RAAT, the P waves in leads V1 and V2 are often negative with notching (Supplemental Figure 1, arrows), compared with a biphasic P-wave in lead V1 and biphasic and/or positive P waves in lead V2 during sinus rhythm (Supplemental Figure 1, dot).
The negative P waves during RAAT occur because the RAA is located anterior to the sinus node, with activation moving away from the electrodes of leads V1 and V2. Supplemental Figure 2 and Video 1 compare the anterior location of the RAAT with the sinus node, recorded from a multipolar catheter during this patient’s catheter ablation. To avoid misinterpretation of the rhythm, it is important to compare the presenting ECG with sinus rhythm to evaluate proper precordial lead placement. Improper positioning of the precordial leads can create biphasic and/or negative P waves in leads V1 and V2 during sinus rhythm (2).
Focal RAAT is a rare focal AT (3). When recognized, catheter ablation is effective, with a low incidence of recurrence reported in these patients. This patient initially was misdiagnosed with inappropriate sinus tachycardia and referred for a tilt-table test. It is important to have a high suspicion of focal AT in patients with inappropriate sinus tachycardia, because untreated AT has been associated with the development of tachycardia-mediated cardiomyopathy in up to 37% of patients (1). In this patient, successful ablation eliminated her RAAT. The patient’s palpitations resolved, and her quality of life significantly improved after ablation.
Funding Support and Author Disclosures
Dr Ho has received research grants from the National Institutes of Health (5KL2TR001444) and American Heart Association (19CDA34760021); and holds equity in Vektor Medical Inc. All other authors have reported that they have no relationships relevant to the contents of this paper.
Footnotes
The authors attest they are in compliance with human studies committees and animal welfare regulations of the authors’ institutions and Food and Drug Administration guidelines, including patient consent where appropriate. For more information, visit the Author Center.
Appendix
For a supplemental figure and video, please see the online version of this paper.
Appendix
3D Electroanatomic activation maps comparing the originating sites of the right atrial appendage atrial tachycardia (left) and sino-atrial node (right) in the right atrium in the same right anterior oblique view. The color-coded activation map shows the site of the earliest activation as red and latest sites purple. The earliest originating site is located at the right atrial appendage (left), with intracardiac signals from the mapping catheter shown (right). Note the more anterior location of the right atrial appendage compared to the sino-atrial node, which creates negative p-waves in lead V1-V2. Furthermore, atrial tachycardias arising from the tricuspid annulus have negative p-waves throughout the precordial leads, due to its lower and anterior location.
References
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Associated Data
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Supplementary Materials
3D Electroanatomic activation maps comparing the originating sites of the right atrial appendage atrial tachycardia (left) and sino-atrial node (right) in the right atrium in the same right anterior oblique view. The color-coded activation map shows the site of the earliest activation as red and latest sites purple. The earliest originating site is located at the right atrial appendage (left), with intracardiac signals from the mapping catheter shown (right). Note the more anterior location of the right atrial appendage compared to the sino-atrial node, which creates negative p-waves in lead V1-V2. Furthermore, atrial tachycardias arising from the tricuspid annulus have negative p-waves throughout the precordial leads, due to its lower and anterior location.