Serum reverse T₃ and amiodarone efficacy

The use of serum reverse T₃ (rT₃) levels in the assessment of amiodarone efficacy is controverstal. We prospectivly studied 10 patients with frequent ventricular ectopy and symptomatic ventricular tachycardia (VT) treated with amiodarone. Serial 24‐h Holter monitor, thyroid function studies incliding serum rT₃, and 12‐lead electrocardiogram were performed on each patient at baseline, and at 1, 4, 12, and 24 weeks of oal amiodarone therapy. Serial Holter moniotors on therapy were analysed for 100% suppression of VT, 90% suppression of couplets, and 85% suppression of ventricular ectopic beats (VEBs) compared with baseline Holter, defining patient groups VT−, Co−, and VEB−, respectively. Lack of arrhythmia suppression to this degree defined groups as VT+, Co+, and VEB+. These were no statistically significnat differneces in rT₃ levels between VT+ and VT− groups, Co+ and Co− groups, or the VEB+ and VEB− groups. VT suppression could not be predicted at any rT₃ level. We conclude than serum rT₃ is an insensive means of assessing amiodarone efficacy.