Atrial flutter (AFL) is a common arrhythmia, and its hemodynamic effect depends upon ventricular rate and the severity of underlying heart disease. In AFL, the atrial rate usually is 250-350 beats per minute and atrioventricular conduction is 2:1 or slower. Rarely, AFL can present with 1:1 AV conduction. In a series of 1037 consecutive patients referred for flutter ablation, 8% presented with 1:1 AV conduction.