But the long-term effectiveness of this treatment hasn't been determined. Anticoagulation for chronic atrial flutter is controversial. The risk of thromboembolism in atrial flutter may be too small to warrant this treatment. Common underlying causes, both cardiac and noncardiac, are similar to those for atrial flutter. However, most people with atrial fibrillation have some type of underlying heart disease.
Atrial fibrillation is thought to be due to several coexisting intra-atrial reentry circuits.
On ECG, atrial fibrillation is characterized by an absence of P waves and an irregular, wavy baseline that corresponds to an atrial rate of 350 to 600 bpm. Acute management of atrial fibrillation is the same as for atrial flutter, with immediate cardioversion indicated if the patient is unstable. Medications used to slow the ventricular rate are beta-blockers, calcium channel blockers, and digoxin. To convert to sinus rhythm, the physician may order a Class Ic or Class III antiarrhythmic drug. Ibutilide, a newer Class III antiarrhythmic drug, shows promise in converting both atrial flutter and atrial fibrillation to sinus rhythm.