To the Editor.—We read with interest the article by Roti et al1 regarding the use of a calcium-channel blocker, diltiazem, for the treatment of tachyarrhythmias in hyperthyroid patients. The authors suggest that calcium channel antagonists may be useful when β-blockers are contraindicated, as in asthmatics, or as a possible adjunct to β-blockers in the treatment of thyrotoxicosis. Unfortunately, as the authors suggest, they did not compare the effect of diltiazem with β-blockers nor take into consideration the possibility of a placebo effect.
We completed a randomized, cross-over, double-blind, pilot study2 comparing the clinical effects of diltiazem (60 mg, orally, four times a day for 1 week) with propranolol (40 mg, orally, four times a day for 1 week) therapy in six newly diagnosed thyrotoxic patients. We found both drugs to be strongly effective in controlling symptoms (18 symptoms were graded) and in improving clinical signs of thyrotoxicosis.
MARK R. MILNER, MARTIN E. GOLDMAN. Diltiazem for the Treatment of Thyrotoxicosis. Arch Intern Med. 1989;149(5):1217. doi:10.1001/archinte.1989.00390050163038