What characterizes the P wave in Atrial Fibrillation?

In Atrial Fibrillation (AF), the characteristic finding is that the P wave is non-existent. Instead, the ECG shows a chaotic, irregular baseline that appears wavy or undulating. This is a result of rapid and disorganized electrical activity occurring in the atria, which means there are no distinct, identifiable P waves as seen in normal sinus rhythm.

The irregularity in the baseline indicates that multiple atrial foci are firing electrical impulses, leading to the quivering of the atria rather than a coordinated contraction. Hence, the absence of defined P waves and the presence of this wavy baseline are hallmark features of Atrial Fibrillation. This can be crucial for diagnosis and helps differentiate Atrial Fibrillation from other arrhythmias where P waves might still be present or more apparent.