Page et al 2015 ACC/AHA/HRS SVT Guideline e541 are more common in patients with longer-duration persistent AF or more dilated left atria or when linear ablation lesions Non reentrant focal arrhythmias often origi- nate at lesion edges or reconnected segments of prior isolated Reisolation of the pulmonary vein and ablation of any nonpulmonary vein foci are often effective in treating these arrhythmias. Detailed activation and entrain- ment mapping of the tachycardia during a second procedure result in effective ablation in approximately 90% of patients.335 Although right atrial CTI-dependent flutter may also occur, most of the tachycardias originate in the left atrium. As with all types of atrial flutter, it may be very difficult to achieve rate control in patients with post AF ablation non CTI-dependent flutter (far more so than in patients with preablation AF). When the ventricular response cannot be controlled with common rate-control medications, attempts at restoration of sinus rhythm with pharmacological therapy and cardioversion are often required. Many of the atrial flut- ters that are observed during the first 3 months after catheter ablation or after cardiac surgery will not recur later on. For this reason, it is advised that attempts at ablation of atrial flut- ter after AF ablation be deferred until after the 3-month wait- Rarely, pharmacological therapy and attempts at rhythm control with antiarrhythmic drug therapy fail to adequately control atrial flutter during the 3 months after AF ablation. In this situation, early repeat ablation is warranted. 7.3. Acute Treatment: Recommendations Recommendations for Acute Treatment of Atrial Flutter COR LOE Recommendations I A 1. Oral dofetilide or intravenous ibutilide is useful for acute pharmacological cardioversion in patients with atrial flutter.119,340 346 See Online Data and 17. 