Short-Term Effects of β-adrenergic Antagonists and Methimazole in New-Onset Thyrotoxicosis Caused by Graves' Disease

Objective beta-adrenergic antagonists (beta-blockers) are often used to attenuate the hyperadrenergic symptoms of Graves' disease (GD), including palpitation. Although beta-blockers reduce the heart rate, cardiac output and oxygen consumption, no firm evidence exists regarding the effects of combined therapy with beta-blockers and anti-thyroid drugs. The objective is to elucidate the effects of beta-blockers on anti-thyroid drug therapy in GD. Methods Patients newly diagnosed with mild GD were randomly assigned to receive methimazole with or without beta-blockers in a prospective multi-center survey. The heart rate and thyroid function were measured and the quality of life was assessed using original and SF-36 questionnaires at 0 and 4 weeks. Results A total of 28 patients were enrolled in the study. Fourteen patients (one man, 13 women) were randomly assigned to the group treated with beta-blockers and 14 patients (one man, 13 women) were randomly assigned to the group not treated with beta-blockers. Although no significant differences in the improvement of thyroid function were observed between the two groups, the heart rates improved more significantly in the group treated with beta-blockers. Specific symptoms, such as easy fatigability and shortness of breath, also improved more significantly with the beta-blocker treatment. In addition, 'physical functioning' assessed with the SF-36 questionnaires significantly improved only in the group treated with beta-blockers. Conclusion Although beta-blockers may not reinforce the effects of anti-thyroid drugs on thyroid function, at least during the course of one month, they are effective in reducing heart rates and ameliorating specific symptoms in patients with mild GD.