Real-life Data on the Effect of Medical Therapy for Amiodarone-induced Thyrotoxicosis on CV Events and Hospitalizations

Context: Patients with amiodarone-induced thyrotoxicosis (AIT) often receive initial therapy for thyrotoxicosis in several different medical settings before admission to a referral center.

Objective: This work aimed to determine whether first-line medical therapy (ie, therapies for thyrotoxicosis at first diagnosis of AIT) affects the outcome of AIT patients.

Methods: A single-center historical-prospective cohort study was conducted on 313 AIT patients. Clinical and biochemical data were collected at first diagnosis, at a referral center, and during the course of AIT. Primary outcomes were cardiovascular (CV) events and hospitalizations. First-line therapies were considered appropriate when they included glucocorticoids for type 2 AIT and methimazole for type 1 AIT at the approved dose, either alone (optimal medical therapy, OMT) or in combination (right-dose combination therapy, RCT). Other therapies were considered not appropriate, including no therapy. Duration of exposure to thyrotoxicosis was the time from first diagnosis of AIT to its remission.

Results: A total of 34.5% patients received appropriate therapies (28.1% OMT, 6.4% RCT), whereas the remaining (65.5%) received inappropriate therapies. CV events and hospitalizations were more frequent in patients who received inappropriate therapies (33.2% vs 4.5%, and 24.9% vs 6.5%, respectively; P < .0001 for both). Appropriate therapies reduced serum thyroid hormone concentrations (P = .018) from first diagnosis to referral, unlike the inappropriate therapies. The duration of exposure to thyrotoxicosis was longer in patients receiving inappropriate therapies and was a risk factor for arrhythmias (hazard ratio [HR] 1.004; P = .0008), major acute CV events (HR 1.004; P = .020), and hospitalizations (HR 1.006; P < .0001).

Conclusion: The first medical therapy of AIT influences the exposure time to thyrotoxicosis and the occurrence of CV events and hospitalizations.