What is the clinical evidence from this study?

Study design: Cohort. Population: Amiodarone-induced thyrotoxicosis (n=71). Intervention: Amiodarone therapy and withdrawal vs. Patients without late AIT. Primary outcome: Incidence of late amiodarone-induced thyrotoxicosis (AIT) after amiodarone withdrawal.

January 1, 2013Circulation Journal21 citationsOpen Access

Amiodarone-Induced Thyrotoxicosis Late After Amiodarone Withdrawal

AYAtsuhiko YagishitaElectrophysiology HHHitoshi HachiyaElectrophysiology MKMihoko KawabataKanagawa Rehabilitation Hospital

Key Result

Late amiodarone-induced thyrotoxicosis occurred in 7% of patients after amiodarone withdrawal and was significantly associated with prior amiodarone-induced hypothyroidism (100% vs. 24%, P=0.002) and longer therapy duration.

Study Design

Type

Cohort (n=71)

Multicenter

Structured PICO

What is the incidence and what are the clinical characteristics of amiodarone-induced thyrotoxicosis occurring late after amiodarone withdrawal?

Population

71 patients (mean age 65 years, 27% female) who discontinued amiodarone after at least 1 month of therapy, followed retrospectively for a mean of 37 months to determine the incidence of late amiodarone-induced thyrotoxicosis.

Exposure

Amiodarone withdrawal after at least 1 month of therapy

Comparator

Patients who did not develop late amiodarone-induced thyrotoxicosis (non-AIT group)

Outcome

Incidence and clinical characteristics of amiodarone-induced thyrotoxicosis (AIT) occurring late after amiodarone withdrawalsafety

Amiodarone-induced thyrotoxicosis can develop months after drug withdrawal, particularly in patients with a history of amiodarone-induced hypothyroidism and long treatment duration, highlighting the need for continued thyroid monitoring.

Limitations

Retrospective study design with a small sample size.
Thyroid function was not fully evaluated at regular intervals in some patients, which may have led to an underestimation of asymptomatic late AIT incidence.
Retrospective design with a small sample size
Thyroid function was not fully evaluated at regular intervals in some patients, potentially leading to underestimation of asymptomatic late AIT

Abstract

BACKGROUND: Amiodarone-induced thyrotoxicosis (AIT) may develop long after amiodarone withdrawal. This study sought to determine the incidence and clinical characteristics of AIT after amiodarone withdrawal. METHODS AND RESULTS: The incidence and clinical characteristics of AIT were examined retrospectively in 71 patients (51 males, mean age 65±13 years) whose amiodarone therapy had been discontinued after at least 1 month of administration. Five (7%) patients developed AIT late after amiodarone withdrawal (11±3 months): 2 patients exhibited exacerbation of heart failure by atrial fibrillation, 2 developed dyspnea on exertion, and 1 patient was asymptomatic. The patients who developed AIT had a high incidence of amiodarone-induced hypothyroidism during amiodarone therapy (100 vs. 24%, P=0.002), had received amiodarone therapy for longer (76±86 months vs. 16±22 months, P<0.001), with a larger cumulative dose (271.1±268.5 g vs. 63.4±86.5 g, P<0.001) compared with those who did not. In all 5 patients, AIT resolved spontaneously within 5 months without the use of steroids. CONCLUSIONS: Occurrence of amiodarone-induced hypothyroidism during amiodarone therapy and long duration of therapy may be cautionary markers of late AIT.

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