What does an Electrocardiogram (ECG) with multiple P waves indicate?

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Last updated: March 10, 2025 • View editorial policy

From the Guidelines

An Electrocardiogram (ECG) with multiple P waves typically indicates a condition such as multifocal atrial tachycardia (MAT), atrial flutter, or second-degree heart block, where the atria contract at abnormal rates, resulting in multiple P waves for each QRS complex. To diagnose the condition, it's essential to examine leads II, V1, and V2, which typically show P waves most clearly 1. The presence of multiple P waves can be associated with various underlying conditions, including pulmonary disease, pulmonary hypertension, coronary disease, and valvular heart disease, as well as hypomagnesemia and theophylline therapy 1. In the case of MAT, the ECG will show at least 3 distinct morphologies of P waves, with a rapid, irregular rhythm and variable P-P, P-R, and R-R intervals 1. Atrial flutter, on the other hand, is characterized by a saw-tooth pattern of regular atrial activation, with an atrial rate typically ranging from 240 to 320 beats per minute 2. Second-degree heart block, particularly Mobitz type II, can also present with multiple P waves, where some P waves are not followed by QRS complexes. It's crucial to manage the underlying condition and control heart rate, with intravenous magnesium and verapamil being potential treatment options 1. In real-life clinical practice, it's essential to prioritize the patient's morbidity, mortality, and quality of life when diagnosing and treating conditions associated with multiple P waves on an ECG. Key considerations include:

  • Examining leads II, V1, and V2 to identify multiple P waves
  • Distinguishing between MAT, atrial flutter, and second-degree heart block
  • Managing underlying conditions and controlling heart rate
  • Considering treatment options such as intravenous magnesium and verapamil.

From the Research

ECG Interpretation

An Electrocardiogram (ECG) with multiple P waves can indicate various conditions, including:

  • Conduction disturbances in the atria, as seen in a case of widely split double P waves with marked intra-atrial conduction delay 3
  • Atrial fibrillation (AF), where prolonged and highly fragmented P-waves have been observed in patients prone to AF 4
  • Paroxysmal atrial fibrillation, where premature P-wave patterns may help identify the source of firing 5
  • Electrocardiogram voltage attenuation, which can lead to shortening of the duration of P-waves, QRS complexes, and QT intervals 6

P-Wave Abnormalities

P-wave abnormalities can have prognostic implications and should trigger the search for associated conditions, such as:

  • Right atrial enlargement, often related to pulmonary disease or pulmonary hypertension 7
  • Interatrial block (IAB), defined as a P-wave ≥120 ms with a biphasic morphology in inferior leads, which is a risk factor for supraventricular tachyarrhythmias, stroke, left ventricular dysfunction, and mortality 7

Key Findings

Key findings from the studies include:

  • Multiple discrete lesions in the right atrium can constitute a unique electrical atriopathy 3
  • Morphological and time-domain characteristics of the P-wave can distinguish between patients with AF relapse and patients without 4
  • Premature P-wave patterns can be characterized by more positive P waves in lead V1, indicating a left atrial origin in the ectopic foci 5
  • Attenuation of the ECG voltage can lead to shortening of the duration of P-waves, QRS complexes, and QT intervals 6

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

A case of widely split double P waves with marked intra-atrial conduction delay.

Journal of cardiovascular electrophysiology, 1997

Research

P-wave characteristics after electrical external cardioversion: predictive indexes of relapse.

Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference, 2010

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.