Although the atrial rates for flutter typically range from 250 bpm to 330 bpm, the rates may be slower in patients with severe atrial dis- ease or in patients taking antiarrhythmic agents or after unsuc- cessful catheter ablation.310 Atrial flutter can occur in clinical settings similar to those associated with AF, and atrial flutter can be triggered by AT or It is common for AF and atrial flutter to coexist in the same patient. After CTI ablation, 22% to 50% of patients have been reported to develop AF after a mean follow-up of 14 to 30 months, although 1 study reported a much higher rate ofAF devel- opment, with 82% of patients treated by catheter ablation for atrial flutter manifestingAF within 5 years.312 Risk factors for the mani- festing AF after atrial flutter ablation include prior AF, depressed left ventricular function, structural heart disease or ischemic heart disease, inducible AF, and increased LA size.121,312 316 Atrial flutter may result from antiarrhythmic therapy of AF, particularly when flecainide, propafenone, or amiodarone is used for treatment of AF.317,318 In those patients with atrial flutter resulting from antiarrhythmic therapy of AF, ablation of the CTI-dependent flutter may prevent recurrent flutter while antiarrhythmic therapy for AF is continued.318 Patients with atrial flutter are thought to have the same risk of thromboembolism as patients with AF; therefore, Figure 12. Acute treatment of AVNRT. Colors correspond to Class of Recommendation in Table 1; drugs listed alphabetically. *For rhythms that break or recur spontaneously, synchronized cardioversion is not appropriate. AVNRT indicates atrioventricular nodal reentrant tachycardia; and IV, intravenous. Recommendations for Management of Symptomatic Patients With Manifest Accessory Pathways COR LOE Recommendations I B-NR 1. 