Which EKG finding is indicative of atrial fibrillation?

Atrial fibrillation is characterized by the presence of fibrillatory waves, which are irregular and chaotic electrical signals in the atria. These waves indicate that instead of a normal sinus rhythm, the atria are quivering rather than contracting effectively. This results in an irregularly irregular rhythm on the EKG. The absence of clear P waves and the presence of these small, erratic waves are distinct features of atrial fibrillation.

Regular P-P intervals signify a normal atrial rhythm, which is not present in atrial fibrillation. U waves, which are occasionally seen in EKGs, are typically associated with electrolyte imbalances or other cardiac conditions but are not indicative of atrial fibrillation. Similarly, a regular QRS complex does not provide information about atrial activity and could suggest other types of arrhythmias that are not atrial fibrillation. Therefore, the presence of fibrillatory waves is the key finding that confirms a diagnosis of atrial fibrillation.