Diagnosis of atrial fibrillation is made via an electrocardiogram (ECG) recording. Any arrhythmia that has the ECG characteristics of AF and lasts sufficiently long for a 12-lead ECG to be recorded, or at least 30 seconds on a rhythm strip, should be considered an AF episode.[6] The diagnosis requires an ECG or rhythm strip demonstrating: 1) "absolutely" irregular RR intervals (in the absence of complete AV block), 2) Absence of distinct P waves on the surface ECG, and 3) an atrial cycle length (when visible) that is usually variable and less than 200 msec. [7]