Xamoterol improves the Control of Chronic Atrial Fibrillation in Elderly Patients

Abstract

Twenty digitalized elderly patients with chronic atrial fibrillation were randomized into a double-blind cross-over study. None was in overt heart failure and all were taking < 80 mg frusemide daily. They received xamoterol 200 mg b.d. for 2 months with their usual dose of digoxin for 1 month and placebo digoxin for the other month. Twenty-four-hour heart rate analysis was done at baseline and at the end of each treatment period. Compared with baseline digoxin, xamoterol alone significantly increased nocturnal minimum heart rate [85 +/- 17 vs. 62 +/- 9 (mean +/- SD), p < 0.0001] without affecting daytime maximum heart rate (132 +/- 18 vs. 122 +/- 20, p = NS). Compared with baseline digoxin, xamoterol plus digoxin significantly increased nocturnal minimum heart rate (68 +/- 8, p < 0.05) and reduced daytime heart rate (114 +/- 17, p < 0.05). The mean number of pauses > 1.5 s was significantly reduced by xamoterol alone. Walking distance in 6 minutes was 406.1 +/- 27.1 m (mean +/- SE) at baseline and improved significantly on both treatments (450.3 +/- 19.8 on xamoterol; p < 0.02 and 453.7 +/- 19.2 on xamoterol plus digoxin; p < 0.01). No significant change was found in subjective measurements of palpitations, breathlessness and well-being using visual analogue scales. Xamoterol combined with digoxin improves effort tolerance and heart-rate control by reducing diurnal tachycardia and nocturnal bradycardia and pauses.

Chronic atrial fibrillation: a systematic review of medical heart rate control management

“…A randomised, controlled study by Hsieh et al aimed at the suppression of ventricular arrhythmias in a group of patients with AF found that treatment with sotalol improved exercise tolerance and reduced 24 h mean HR compared with no treatment 29. In another study by Lawson-Matthew et al treatment with xamoterol resulted in improved exercise tolerance at the expense of increased HR over a 24 h period compared with digoxin 26. Six studies report no improvement in exercise capacity with β-blockers alone 21 23 24 27 28 30…”

“…However, the effect of this combination on exercise tolerance is inconsistent, with some studies reporting deterioration in exercise capacity,31–33 35 41 some improvement26 36 39 and most no change 22 24 27 28 31 34 37 40 42 44…”

“…Two double blind, randomised, cross-over studies21 26 evaluated xamoterol alone (xamoterol was discontinued in the UK in 2000). Ang et al found that xamoterol alone improved exercise HR and also reduced HR variability compared with placebo and digoxin 21.…”

“…Ang et al found that xamoterol alone improved exercise HR and also reduced HR variability compared with placebo and digoxin 21. Lawson-Matthew et al reported that in 25 patients xamoterol when used alone improved exercise tolerance but increased 24 h HR 26. The combination of xamoterol with digoxin resulted in improved exercise tolerance and also less HR variability compared with digoxin alone.…”

“…Significant side effects were reported in the above studies including heart failure, pulmonary oedema, intermittent claudication, arrhythmia, postural dizziness, and bronchospasm. Two studies report worsening heart failure symptoms on withdrawal of digoxin 26 27. One of these27 recruited patients with heart failure and LVEF <40%, while the other one recruited patients with mild heart failure only (New York Heart Association functional class I or II).…”