Comparison of digoxin versus low-dose amiodarone for ventricular rate control in patients with chronic atrial fibrillation

1. Rapid ventricular rate (VR) and rhythm irregularity during atrial fibril lation (AF) impair cardiac performance. Although digoxin has been widely us ed in patients with AF, its efficacy for the control of VR and rhythm irreg ularity is unsatisfactory. Whether low-dose amiodarone is more effective re mains unclear. 2. We randomized 16 patients (13 male, three female; mean (+/- SD) age 63 /- 9 years) with chronic AF to receive either digoxin or amiodarone for 24 weeks. At baseline and at 12 and 24 weeks follow up, Holter monitor recordi ng and cardiopulmonary exercise test were performed to assess VR and rhythm irregularity control and exercise capacity. 3. Seven and nine patients received digoxin and amiodarone, respectively. A fter 12 and 24 weeks treatment, both digoxin and amiodarone significantly d ecreased the mean ambulatory VR and the VR during peak exercise compared wi th baseline (all P < 0.05). At 24 weeks, there were no significant differen ces between digoxin and amiodarone in the percentage reduction in VR during ambulatory (27 +/- 13 vs 25 +/- 12%, respectively; P = 0.8) and peak exerc ise (13 +/- 12 vs 12 +/- 10%%, respectively; P = 0.6). 4. The rhythm irregularity, as measured by SD of RR intervals and the root mean square of the SD of RR intervals, and the exercise capacity, as measur ed by exercise workload, maximal oxygen consumption (VO2), minute ventilati on, ventilatory equivalent and oxygen pulse, were not significantly changed after treatment with digoxin or amiodarone (all P > 0.05). 5. Quality of life, determined by SF-36 questionnaire, and AF symptomatolog y, as measured by the AF Symptom Checklist, were also not significantly cha nged after treatment with digoxin or amiodarone (all P > 0.05). 6. In conclusion, digoxin and low-dose amiodarone had similar efficacy in t he control of VR during ambulatory activity and exercise. However, both wer e less efficacious during exercise and did not significantly affect rhythm irregularity, exercise capacity, quality of life and AF symptomatology in p atients with chronic AF.