Ibutilide for Conversion of Atrial Fibrillation or Flutter in Community Emergency Departments

Posted on by Dr Clemens
Daniel J. Pallin, MD, MPH reviewing Vinson DR et al. Ann Emerg Med 2017 Sep 29.

Ibutilide successfully cardioverted 55% of patients within 4 hours in a multicenter retrospective cohort study.

Ibutilide is a class III antiarrhythmic drug that is effective for cardioverting atrial fibrillation or flutter (AF/F). However, reported rates of induced ventricular tachycardia of around 1% may discourage its use (NEJM JW Cardiol and Heart 1998; 79:568). To examine safety and efficacy in real-world practice, investigators reviewed data from ibutilide administrations for AF/F at 21 community emergency departments (EDs) in the Kaiser Permanente Northern California system from 2009 to 2015.

Of 361 patients, 98% had recent-onset AF/F, 5% had history of heart failure, 29% had a prolonged (>480 ms) initial QTc interval, and 3% were hypokalemic (<3.5 mEq/L). The average ibutilide dose was 1.5 mg. Conversion to sinus rhythm within 4 hours occurred in 55% of patients; of these, 0.6% experienced ventricular tachycardia and ultimately did well. About half the cohort was pretreated with magnesium (1 or 2 g in almost all cases).

COMMENT — EMERGENCY MEDICINE

Daniel J. Pallin, MD, MPH

Ibutilide is a good option for cardioversion of atrial fibrillation. As highlighted in this study, it is safe, but inferior to electrical cardioversion, which can restore sinus rhythm in 89% of patients with AF/F (NEJM JW Emerg Med May 2012 and Emerg Med J 2012; 29:188). When cardioversion is indicated, my approach is propofol sedation followed by electrical cardioversion, reserving ibutilide for patients who prefer not to undergo sedation or electrical cardioversion. As the authors note, pretreatment with magnesium (4 g) is advisable, because it potentiates the effect of ibutilide and may decrease the incidence of torsades de pointes, a rare but feared complication.

COMMENT — CARDIOLOGY

Mark S. Link, MD

Ibutilide is an effective means of restoring sinus rhythm. However, the incidence of ventricular tachycardia and ventricular fibrillation is around 1%. If patients are given ibutilide, they must be monitored for a minimum of 4 hours if the QTc interval remains prolonged. In addition, the risk for thromboembolism with conversion of AF is related to the length of time a patient is in AF, not whether the patient is chemically or electrically converted. Thus, individuals in AF for longer than 24 to 48 hours or for an unknown duration should not receive ibutilide unless transesophageal echocardiography confirms no thrombus.

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