Oral dofetilide or intravenous ibutilide is useful for acute pharmacological cardioversion in patients with atrial flutter.119,340 346 See Online Data and 17. Pharmacological cardioversion of atrial flutter is generally less effective than synchronized cardioversion and carries the potential risk of proarrhythmia but can be an option when sedation is not available or not well tolerated or when indicated by patient preference. Intravenous ibutilide converts atrial flutter to sinus rhythm in approximately 60% of cases.342 The major risk is torsades de pointes, which is more likely to occur in patients with reduced left ventricular ejection fraction. Patients receiving ibutilide should undergo continuous ECG monitoring during administration and for at least 4 hours after completion of dosing. Pretreatment with magnesium can increase the efficacy and reduce the risk of torsades de pointes.119 Anticoagulation issues for chemical cardioversion are the same as those for electrical cardioversion of atrial flutter.10 I B-R Intravenous or oral beta blockers, diltiazem, or verapamil are useful for acute rate control in patients with atrial flutter who are See Online Data and 17. It is often more difficult to achieve rate control for atrial flutter than for AF. Nonetheless, effective rate control may be achieved with beta blockers, diltiazem, or verapamil in patients with atrial flutter through a direct effect on the AV node. Hypotension is the main adverse effect. Intravenous diltiazem is the preferred intravenous calcium channel blocker for acute rate control because of its safety and Diltiazem and verapamil should be avoided in patients with advanced heart failure and in patients with heart block or sinus node dysfunction in the absence of pacemaker therapy. Verapamil and diltiazem also should not be used in patients with known pre- excitation. The heart rate control achieved with beta blockers is similar to that seen with verapamil and diltiazem. 