XAMOTEROL IN SINUS NODE DISEASE

A pharmacological alternative to pace-maker implantation would be usef ul in some patients with sinoatrial disorder particularly since the si ngle lead ventricular system usually fitted has disadvantages. Xamoter ol, a cardioselective beta-receptor partial agonist, has been shown to increase heart rate both in animals and in man. We, therefore, studie d the effects of Xamoterol in patients with sinoatrial disease in a do uble blind, cross-over trial in 10 patients. Mean heart rates and numb er and duration of pauses were compared during the treatment phases of the trial with Holter monitoring. Mean heart rates were significantly increased between 01:00 h and 05:00 h (P less-than-or-equal-to 0.02) and between 05:00 h and 09:00 h (P less-than-or-equal-to 0.01) on Xamo terol. The number of sinus pauses were eliminated or reduced on Xamote rol in six patients, but there was an increased frequency in three pat ients. Xamoterol, therefore, does increase the heart rate and reduce t he number of pauses in sinoatrial disorder, but only in some patients.