• H F Tse, Y M Lam, C P Lau, B M Cheung, and C R Kumana.
• Division of Cardiology, Department of Medicine and the Institute of Cardiovascular Science and Medicine, University of Hong Kong, Queen Mary Hospital, Hong Kong, China. hftse@hkucc.hku.hk
• Clin. Exp. Pharmacol. Physiol. 2001 May 1; 28 (5-6): 446-50.

Abstract1. Rapid ventricular rate (VR) and rhythm irregularity during atrial fibrillation (AF) impair cardiac performance. Although digoxin has been widely used in patients with AF, its efficacy for the control of VR and rhythm irregularity is unsatisfactory. Whether low-dose amiodarone is more effective remains 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 recording 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. After 12 and 24 weeks treatment, both digoxin and amiodarone significantly decreased the mean ambulatory VR and the VR during peak exercise compared with baseline (all P < 0.05). At 24 weeks, there were no significant differences between digoxin and amiodarone in the percentage reduction in VR during ambulatory (27 +/- 13 vs. 25 +/- 12%, respectively; P = 0.8) and peak exercise (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 measured by exercise workload, maximal oxygen consumption (VO2), minute ventilation, 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 symptomatology, as measured by the AF Symptom Checklist, were also not significantly changed after treatment with digoxin or amiodarone (all P > 0.05). 6. In conclusion, digoxin and low-dose amiodarone had similar efficacy in the control of VR during ambulatory activity and exercise. However, both were less efficacious during exercise and did not significantly affect rhythm irregularity, exercise capacity, quality of life and AF symptomatology in patients with chronic AF.

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