Endocrine Abstracts

Background: Amiodarone-induced thyrotoxicosis (AIT) is a challenging disease associated with increased morbidity and mortality. The European Thyroid Association guidelines define the role for total thyroidectomy in the management of AIT. However, these recommendations were based on small series, which often lead to heterogeneous results and, importantly, did not identify patients who may benefit from surgery.

Materials and methods: Observational longitudinal cohort study involving 207 AIT patients followed at University of Pisa over a 27-year span. Fifty-one patients received total thyroidectomy and 156 received optimal medical therapy, as defined by the most recent guidelines. Indications to surgery were revised, and surgical candidates were clustered according to the degree of urgency, thus leading to the identification of four surgical groups. Data at diagnosis of AIT and during the course of the disease were recorded. Death and its causes were assessed by telephone interview. Intergroup comparisons were performed between surgical and medical patients, and intragroup comparisons were performed according to the four identified surgical groups. Survival was estimated using the Kaplan-Meier method.

Results: Ten-years overall mortality rate and 5-years cardiovascular-specific mortality rate were lower in the surgical rather than in the medical therapy group (P = 0.04 and P = 0.01, respectively). This result was due to the subset of patients affected by moderate-to-severe systolic dysfunction, whereas no differences were reported for patients with normal or mildly-reduced systolic function. Compared to low-risk patients who underwent total thyroidectomy in the elective setting, high-risk patients submitted urgently to surgery due to a worsening of the underlying cardiac conditions were operated more rapidly (P = 0.018), with a lower left ventricular ejection fraction (P < .0001)and with higher thyroid hormone concentrations (P = 0.0002 and P = 0.013 for FT4 and FT3), but without any difference in the survival rates (P = 0.486). At Cox multivariate analysis presurgical thyroid hormone concentrations were not significant predictors of mortality.

Conclusions: Total thyroidectomy should be considered for AIT patients with moderate-to-severe systolic dysfunction, since it is associated with improved survival compared to optimal medical therapy. Patients affected by severe underlying cardiac disease should undergo surgery urgently, avoiding any possible delay aimed at a preliminary restoration of euthyroidism.