Ibutilide Fumarate for the Conversion of Atrial Arrhythmias After Cardiac Surgery - Ibutilide Fumarate for the Conversion of Atrial Arrhythmias After Cardiac Surgery


The goal of this double-blind, placebo-controlled, randomized study was to evaluate the safety and efficacy of ibutilide in conversion of atrial arrhythmias among patients following cardiac surgery.


Ibutilide may be both safe and efficacious in converting atrial arrhythmias among postoperative cardiac surgery patients.

Study Design

Study Design:

Patients Enrolled: 302
Mean Follow Up: 72 hours
Female: 24
Mean Ejection Fraction: 49% had a normal ejection fraction; 31% had an ejection fraction <40%.

Patient Populations:

  • 18 years or older
  • Weight <300 pounds
  • Males or postmenopausal/surgically sterile females
  • Atrial fibrillation or atrial flutter persisting longer than one hour and less than three days following coronary artery or cardiac valvular surgery
  • Sinus rhythm at the time of surgery
  • Corrected QT interval ≤440 ms


  • Prior exposure to ibutilide
  • History of torsades de pointes
  • Hemodynamic instability
  • Congestive heart failure
  • Heart rate <60 bpm
  • Myocardial infarction within 30 days
  • Severe hepatic impairment, hyperthyroidism, or electrolyte abnormality
  • Treatment with pressor drugs other than low-dose dopamine or dobutamine
  • Treatment with any class I or III antiarrhythmic drug within five half-lives of enrollment

Primary Endpoints:

Conversion of the atrial arrhythmia to sinus rhythm for any period of time within 90 minutes after initiating ibutilide or placebo infusion

Secondary Endpoints:

Cardiovascular adverse events included hypotension, QT prolongation, brady- or tachyarrhythmias, or congestive heart failure. Noncardiovascular adverse events included nausea, constipation, vomiting, fever, and diaphoresis. Adverse events were monitored for 72 hours after initial infusion.

Drug/Procedures Used:

  • Placebo
  • 0.25 mg of ibutilide fumarate
  • 0.50 mg of ibutilide fumarate
  • 1.0 mg of ibutilide fumarate
The dose was repeated if unsuccessful after 10 minutes. Those weighing less than 60 kg were randomized to placebo, 0.0025, 0.005, or 0.01 mg/kg.

Principal Findings:

  • Ibutilide at 0.25, 0.5, and 1.0 mg was associated with conversion to sinus rhythm at 90 minutes of 40%, 47%, and 57% compared to a 15% conversion rate in the placebo group (p=0.0001).
  • Those with atrial flutter had higher rates of conversion compared to those with atrial fibrillation (78% vs. 44% in the 1 mg group).
  • Higher doses of ibutilide were more often associated with lower time to conversion (23, 33, and 36 minutes for the 1, 0.5, and 0.25 mg ibutilide groups, respectively).
  • Polymorphic ventricular tachycardia occurred in 2.3% and 1.2% of the ibutilide-treated patients and placebo group, respectively.
  • Of those converted to sinus rhythm, 63% of those in the ibutilide-treated groups and 62% of those in the placebo group remained in sinus rhythm for 24 hours.
  • There was no significant difference in noncardiovascular adverse events.
  • There was a reduction in heart rate of 1.5 bpm and 15.4 bpm in the placebo and 1 mg ibutilide groups, respectively (p<0.05).
  • Polymorphic ventricular tachcardia was more common (2.3% vs. 1.2% in the ibutilide and placebo groups, respectively).


Among patients who develop atrial fibrillation or atrial flutter following cardiac surgery, ibutilide treatment was associated with a higher rate of conversion to sinus rhythm and with increased rates of polymorphic ventricular tachycardia within 72 hours.


VanderLugt JT, Mattioni T, Denker S, et al. Efficacy and safety of ibutilide fumarate for the conversion of atrial arrhythmias after cardiac surgery. Circulation 1999;100:369-75.

Clinical Topics: Arrhythmias and Clinical EP, Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Cardiac Surgery and Arrhythmias, Statins

Keywords: Tachycardia, Ventricular, Cardiac Surgical Procedures, Heart Rate, Atrial Flutter, Sulfonamides

< Back to Listings