| Abstract: | Following 4 weeks on placebo, eighteen patients with bradycardia-tachycardia syndrome (BTS) were treated with 100 mg xamoterol twice daily for 2-4 weeks. Ambulatory 24 h Holter electrocardiogram recordings showed that xamoterol decreased maximum heart rate from 140 +/- 5.1 to 107 +/- 6 beats min-1 (P < 0.001) during exercise, increased minimum heart rate from 43 +/- 1.7 to 51 +/- 2.4 beats min-1 (P < 0.005) at night and shortened maximum duration of sinus arrest from 3438 +/- 484 to 1767 +/- 202 ms (P < 0.005) in BTS. Symptomatically, patients reported that palpitations were improved and syncopal attacks disappeared. Although the study has the limitation of an open design, effects of treatment were objectively evaluated using Holter monitoring by investigators who reviewed the recordings in a blinded manner. The findings suggest that xamoterol may be useful in the treatment of BTS. Further studies are needed to evaluate fully its therapeutic potential in this condition. |
