After atrial fibrillation, atrial flutter is the next most common and significant atrial arrhythmia. The regular sawtooth flutter waves (F waves) of typical atrial flutter can be seen in ECG leads II, III, and aVF (picture ). The atrial rate is 240-350/min. Antiarrhythmic drugs have proved not to be very effective and, in some cases, even dangerous. Catheter ablation has therefore superseded antiarrhythmic drugs in the prophylactic treatment of atrial flutter. Class IC antiarrhythmic drugs (flecainide, propafenone) are commonly used in the treatment of lone atrial fibrillation, but their use must be avoided in atrial flutter due to the risk of proarrhythmia (1:1 atrial flutter).