5. Management

#### 5.1. Acute management

The clinical presentation will dictate acute therapeutic approach which may include cardioversion or rate control strategy. Cardioversion (electrical or chemical) is usually the initial treatment of choice. Antiarrhythmic medication such as intravenous amiodarone, sotalol, have been reported with a high success rate of chemical cardioversion. These class III antiarrhythmics prolong the refractory period leading slower cycle length which could terminate AFL. Interestingly, intravenous ibutilide has been more effective than the formers up to 76% of patients. Electrical cardioversion at a low energy of 50 J has very high success rate. Overdrive atrial pacing by a catheter in RA or in preexisting pacemaker/defibrillator is an effective alternative option in terminating typical AFL. Anticoagulation by using the same criteria as for AF, prior to cardioversion should be considered [3]. In order to control the rate, oral or intravenous atrioventricular node (AVN) blockers such as verapamil, diltiazem, beta blockers, and digoxin, can be used. However, the rate control is difficult to achieve as opposed to AF.

#### 5.2. Chronic management

If AFL occurs in the context of an acute disease process, long-term rhythm control medication is usually not required once the AFL is converted and the underlying pathologic process is eliminated. However, if there is a certain substrate for AFL recurrence such as enlarged RA or scar, medical suppression of AFL can be extremely difficult. Hence, the ablation procedure with highly successful rate and low complication risk is the approach of choice for typical AFL [7]. However, medication may be tried in some situation (i.e. patient preference). Several antiarrhythmic drugs have been somehow effective in AFL suppression, including class IC (flecainide and propafenone), and class III (usually sotalol and amiodarone) antiarrhythmics. In the absence of SHD, class IC agents are the first line medication. The antiarrhythmic agents should be combined with AVN blockers to avoid the risk of rapid ventricular rates. In fact, class IC drugs have a vagolytic effect on AVN. Although the atrial flutter rate will be slowed, more proportion of these atrial impulses will be conducted through AVN (enhanced conduction), by which net ventricular rate increases [3]. As a result, rapid 1:1 AV conduction is mostly seen if Class IC antiarrhythmic medication is not combined with AVN blockers such as beta blockers (Figure 1e). As mentioned, typical AFL is very amenable to ablation but AV junction ablation and pacemaker implantation may be indicated if rhythm and rate control strategies including ablation have failed in atypical flutter. The anticoagulant policy will be implemented based on the same guideline for AF.
