From the Guidelines
The diagnosis for a condition with multiple P wave morphologies and a normal heart rate that does not qualify as Multifocal Atrial Tachycardia (MAT) is Wandering Atrial Pacemaker (WAP). This arrhythmia is characterized by at least three different P wave morphologies originating from different atrial foci, with a heart rate that remains within the normal range (60-100 beats per minute) 1. Unlike MAT, which requires a heart rate greater than 100 beats per minute, WAP maintains a normal heart rate while still showing the characteristic shifting P wave morphologies.
Key Characteristics of Wandering Atrial Pacemaker (WAP)
- At least three different P wave morphologies
- Normal heart rate (60-100 beats per minute)
- Shifting pacemaker sites due to different areas of the atria temporarily taking over the pacemaking function from the sinoatrial node Wandering Atrial Pacemaker is generally considered a benign arrhythmia and often requires no specific treatment if the patient is asymptomatic 1. It commonly occurs in healthy individuals, particularly athletes with high vagal tone, but can also be seen in patients with underlying heart or lung disease. The shifting pacemaker sites occur because different areas of the atria temporarily take over the pacemaking function from the sinoatrial node, resulting in the varied P wave appearances on ECG while maintaining normal ventricular response rates 1.
From the Research
Diagnosis of Atrial Arrhythmia
The condition described, with multiple P wave morphologies and a normal heart rate, does not qualify as Multifocal Atrial Tachycardia (MAT) due to the normal heart rate, as MAT is typically characterized by an irregular atrial rhythm with a rapid heart rate 2, 3.
Possible Diagnoses
- Ectopic atrial rhythm (EAR) is a possible diagnosis, characterized by an abnormal P wave axis or multiple P wave morphologies, which can be seen on an electrocardiogram (ECG) 4.
- Atrioventricular nodal reentrant tachycardia (AVNRT) is another possible diagnosis, which can be predicted by the presence of EAR on a preablation ECG in pediatric patients 4.
- Other supraventricular tachycardias, such as paroxysmal supraventricular tachycardia (PSVT), may also be considered, although the normal heart rate and multiple P wave morphologies may not be typical of PSVT 5.
Key Characteristics
- Multiple P wave morphologies on ECG
- Normal heart rate
- Does not meet criteria for MAT due to normal heart rate
- May be associated with EAR or AVNRT in certain cases 4