Efficacy and safety of dronedarone in patients with amiodarone-induced hyperthyroidism: a clinical study

M.A. Perrone, J. Babu Dasari, A. Intorcia, R. Morgagni, D. Sergi, F. Battaini, A. De Lorenzo, S. Bernardini, G. Merra, F. Romeo

Division of Cardiology, University of Rome Tor Vergata, Rome, Italy. marco.perrone01@gmail.com

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• Pharmacology

OBJECTIVE: The aim of the study was to examine the safety and efficacy of dronedarone in patients with a history of atrial fibrillation and amiodarone-induced hyperthyroidism.

PATIENTS AND METHODS: We conducted a prospective study to evaluate the use of amiodarone and dronedarone in 124 patients with a history of paroxysmal atrial fibrillation who had no additional structural heart disease. All patients received amiodarone 200 mg qd. Out of 124 patients, 56 (45%) switched to dronedarone 400 mg bid due to amiodarone-induced hyperthyroidism and the remaining 68 patients (55%), with normal thyroid function, continued to receive amiodarone. The follow-up period was 12 months, and the patients were regularly monitored.

RESULTS: The primary outcome after 6 months dronedarone and amiodarone group was 56 and 68, including 38 (68%) and 54 (79.4%) (Odds ratio [OR] = 1.17, 95% confidence interval [95% CI] = 0.68-2.02) patients with sinus rhythm (SR) and 18 (32.14%) and 14 (28.6%) (odds ratio [OR] = 0.64, confidence interval [95% CI] = 0.29-1.40) patients with atrial fibrillation (AF). The secondary outcome after 12 months showed significant difference in thyroid function in the dronedarone group. Out of 46 patients, 24 (56.18%) patients reduced hyperthyroidism compared to the amiodarone group; out of 68, 6 (8.9%) patients were observed to have hyperthyroidism. At 12 months, there were 24 (43%) and 22 (62%) (odds ratio [OR] = 0.75, confidence interval [95% CI] = 0.38-1.49) patients with SR, and 32 (57%) and 26 (38%) (odds ratio [OR] = 0.67, confidence interval [95% CI] = 0.36-1.25) patients with AF.

CONCLUSIONS: In our study, dronedarone appears to be a good therapeutic option in the treatment of atrial fibrillation in patients with amiodarone-induced hyperthyroidism. However, long-term studies are needed to estimate the efficacy and toxicity of both drugs.

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