Morbidity, Mortality and Treatment

Mortality and morbidity in atrial flutter must be considered and are related to:

• Rate-related complications such as heart failure and ischaemia
• Thrombo-embolic events, caused by a pro-thrombotic atrial state and leading to a risk of embolic events approaching that of atrial fibrillation

Both of these issues need to be considered when intervention for atrial flutter is considered.

Treatment of atrial flutter is broadly the same as for atrial fibrillation, though the condition is more sensitive to DC shock and less so to chemical cardioversion [3-4].

The urgency and aims of treatment depend on symptoms, which are usually rate-related.

DC cardioversion

The patient with recent onset flutter and a rapid ventricular rate may be unstable or compromised hypotensive, suffering ischaemic pain or in overt pulmonary oedema. These patients require emergency synchronised DC cardioversion. 25 J may be sufficient though 50-100 J is more reliably effective. Sometimes the first shock converts the rhythm to atrial fibrillation requiring further shocks to achieve sinus rhythm.

Chemical cardioversion

Chemical cardioversion can be achieved best with class III antiarrhythmic drugs such as amiodarone. Sotalol (which has class III action), and flecainide (class Ic) are also used, typically on the advice of a cardiologist.

Rate control

Rate control may be achieved with amiodarone (although this may well also result in cardioversion), beta blockers or calcium channel blockers (e.g. verapamil or diltiazem).

Electrophysiological ablation therapy

Antiarrhythmic drugs maintain sinus rhythm in only 50-60% of patients. Radiofrequency catheter ablation is successful in more than 90% of cases, interrupting the re-entrant circuit in the right atrium and avoiding the long-term toxicity observed with antiarrhythmic drugs.

Anticoagulation

Whilst there are no dedicated studies investigating embolic risk in atrial flutter and the benefits of anticoagulation, current NICE guidance advises risk stratifying patients with flutter in the same way as those with atrial fibrillation. The CHA2DS2-VASc stroke risk score is the recommended stratification tool. Anticoagulation with agents such as apixaban, dabigatran or warfarin should be considered for men with a score of 1 or more, and offered to all patients with a score of 2 or more, taking bleeding risk and patient preference into account.