Canadian Trial of Atrial Fibrillation - CTAF

Description:

The Canadian Trial of Atrial Fibrillation (CTAF) was a head-to-head randomized trial of amiodarone versus either sotalol or propafenone for the maintenance of sinus rhythm in patients with established atrial fibrillation (AF).

Hypothesis:

For patients with AF, amiodarone will be more effective than sotalol or propafenone in maintaining sinus rhythm.

Study Design

Study Design:

Patients Enrolled: 403
Mean Follow Up: Mean 16 months
Mean Patient Age: 65 ± 11
Female: 44
Mean Ejection Fraction: 12% of patients had left ventricular ejection fraction <50%

Patient Populations:

Symptomatic ECG-documented AF lasting at least 10 minutes one or more times in the preceding six months, for which antiarrhythmic drug therapy was planned

Exclusions:

Persistent AF for ≥6 months or AF associated with an acute reversible cause; myocardial infarction within 6 months; cardiac surgery within 30 days; significant renal, hepatic, or pulmonary disease; previous long-term therapy with or intolerance of study drugs; Wolff-Parkinson-White syndrome, prolonged QT interval, bradycardia, or atrioventricular conduction disturbance; New York Heart Association Class III or IV; or need for antiarrhythmic drug therapy for other arrhythmia

Primary Endpoints:

Time to first AF recurrence. Time zero began 21 days after randomization, to allow for completion of drug loading and, if necessary, cardioversion. Recurrence was required to last 10 or more minutes and be confirmed by ECG.

Secondary Endpoints:

Adverse effects from study medication, thromboembolic events, and death

Drug/Procedures Used:

Patients were randomized to amiodarone (10 mg/kg/d x 14 days, 300 mg/d for four weeks, then 200 mg/d) versus sotalol (80-160 mg twice a day based on estimated creatinine clearance) or propafenone (150 mg q6-8 hours or 300 mg twice a day). Patients randomized to the sotalol/propafenone arm underwent a second randomization to determine which drug was used first.

If patients remained in AF, electrical cadioversion was recommended within 21 days of drug initiation. If patients in the sotalol/propafenone arm failed attempted cardioversion with the first assigned drug, they could be switched to the other drug in that arm.

Concomitant Medications:

Amiodarone vs. sotalol/propafenone at three months—
digoxin: 16% vs. 28%
beta-blockers: 18% vs. 15%
calcium channel blockers: 10% vs. 12%
aspirin: 24% vs. 24%
anticoagulants: 53% vs. 61%
thyroid supplement: 11% vs. 7%

Principal Findings:

Over an average of 16 months' follow-up, 35% of patients in the amiodarone group experienced a recurrence of AF versus 63% in the sotalol/propafenone group (p<0.001). The hazard ratio for AF recurrence in the amiodarone group was 0.43 (95% confidence interval 0.32-0.57).

Amiodarone patients were somewhat more likely to discontinue their study drug due to adverse events (18% vs. 11%, p=0.06), mainly due to gastrointestinal and central nervous system symptoms. No differences were observed in death (4.5% vs. 4.0%) or nonfatal major clinical events (18% vs. 17%).

Interpretation:

Among patients with AF, treatment with low-dose (200 mg/d maintenance) amiodarone was associated with a nearly 50% reduction in AF recurrence compared with treatment with sotalol or propafenone. These data are consistent with nonrandomized data and smaller randomized trials suggesting that amiodarone is the most effective drug available for preventing AF recurrence. Patients treated with amiodarone require careful surveillance for potential noncardiac toxicity and adverse events.

References:

Roy D, Talajic M, Dorian P, et al. Amiodarone to prevent recurrence of atrial fibrillation. Canadian Trial of Atrial Fibrillation Investigators. N Engl J Med 2000;342:913-20.

Clinical Topics: Arrhythmias and Clinical EP, Implantable Devices, EP Basic Science

Keywords: Follow-Up Studies, Heart Conduction System, Electric Countershock, Nervous System, Creatinine, Electrocardiography, Recurrence, Propafenone, Sotalol, Confidence Intervals


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