Acute Pharmacological Conversion of Atrial Fibrillation to Sinus Rhythm

Abstract

Atrial fibrillation is a common arrhythmia that affects >2 million adults in the United States, with ≈160 000 new cases diagnosed each year. Although many patients are asymptomatic, those with symptoms can experience palpitations, dyspnea, angina, exertional fatigue, and presyncope. The long-term consequences of atrial fibrillation are well described and include increased risk of thromboembolic events that require chronic anticoagulation in most patients. Reestablishment of sinus rhythm is a key long-term management strategy that would be expected to relieve symptoms, improve hemodynamics, and reduce the risk of thromboembolic complications. Cardioversion is recommended for patients with relatively new-onset atrial fibrillation who are hemodynamically unstable, have uncontrolled rapid ventricular response, or have cardiac ischemia or for acute management of symptoms.1 Options include synchronized direct current cardioversion, which requires conscious sedation to manage the discomfort of the procedure and is associated with ventricular fibrillation in 0.2% of cases, sinus bradycardia or sinus arrest in 1% of cases, and thromboembolism in 1% of cases not adequately anticoagulated.2,3 Pharmacological cardioversion is less effective than direct current cardioversion, but several drugs (dofetilide, flecainide, ibutilide, dofetilide, and propafenone) are currently approved for this indication. These drugs carry risks similar to those of electric cardioversion with the additional concerns of prolonging the QT interval and developing torsade de pointes arrhythmias. Rates of spontaneous conversion, without the attendant risks of pharmacological or electric conversion, have been reported to be as high as 73% within the first 24 hours after onset, with <50% of patients spontaneously converting after 72 hours of atrial fibrillation.4 Given this background, 2 new pharmacological agents to convert atrial fibrillation to sinus rhythm in the acute care setting were reviewed by the Cardiovascular and Renal Drugs Advisory Committee of …