Ibutilide Fumarate for the Conversion of Atrial Arrhythmias After Cardiac Surgery - Ibutilide Fumarate for the Conversion of Atrial Arrhythmias After Cardiac Surgery
Description:
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.
Hypothesis:
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
Exclusions:
- 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
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).
Interpretation:
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.
References:
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.
Keywords: Tachycardia, Ventricular, Cardiac Surgical Procedures, Heart Rate, Atrial Flutter, Sulfonamides
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