This ECG shows atrial flutter with variable block with an atrial rate of about 260 bpm. The flutter waves appear to be positive (upright) in the inferior leads, suggesting a clockwise rotation pattern to the flutter reentrant mechanism, rather than the more common counterclockwise pattern that is associated with negative flutter waves in the inferior leads. A classic right bundle branch block pattern with left anterior fascicular block is present as well.
Unifocal or multifocal atrial tachycardia is excluded as there are no true, discrete P waves, but rather continuous F (flutter) waves. The very fast atrial rate here (about 260/min) also strongly favors flutter rather than atrial tachycardia. The rapid, irregular oscillatory pattern of atrial fibrillation is not seen. Wolff-Parkinson-White (WPW) pattern of conduction is excluded as no delta waves are seen.