Amiodarone-induced thyrotoxicosis (AIT) can cause cardiac decompensation. Type 1 (T1) is treated with anti-thyroid medications (ATM) and Type 2 (T2) with glucocorticoids (GC). Differentiating between types is challenging.
To evaluate the management of AIT at St Vincent’s Hospital, Sydney.
Retrospective audit of 64 patients treated for AIT (2007-2016). Patients were classified as T1 or T2 based on radiological criteria.
Mean age was 60±2y; 81% were male. Initial treatment was ATM in 23 (36%), GC in 17 (27%) and combination (COMB) in 24 (38%). Treatment groups had similar age, gender, cardiac comorbidities and fT3. Median fT4 was 28pmol/L (19-33) in ATM, 40pmol/L (29-47) in GC and 55pmol/L (39-75) in COMB (p=0.002). Proportion of T1 and T2 did not differ between treatment groups. Initial therapy induced euthyroidism in 52% of patients (70% in ATM, 53% GC and 33% COMB; p=0.045). Of those who became euthyroid with initial treatment, there were differences in time to euthyroidism – ATM 100d (49-167), GC 53d (45-99) and COMB 47d (31-65) (p=0.04). Response rate to ATM was the same when only T1 were considered. In contrast, response to GC was higher (83%) when only T2 were included. A further 11% required the addition of a second medication. Thyroidectomy was undertaken in 33%. Compared to patients who responded to medication, thyroidectomy patients were younger (54±3 vs 63±2y; p=0.03), had higher fT4 (54 [31-82] vs 40 [30-46] pmol/L; p=0.056) and tended to have higher prevalence of cardiac failure (81% vs 53%; p=0.09). Despite median American Society of Anesthesiologists classification 4 and preoperative fT4 of 42pmol/L (30–80), no patient experienced cardiorespiratory complications/death.
Patients with AIT had poor response to initial treatment. The poorest response was observed in COMB group, likely related to more severe hyperthyroidism. Thyroidectomy is safe if performed with expertise in cardiac anaesthesia.