Amiodarone-induced thyroidopathy in hospitalized patients: a retrospective observational study

Background. Amiodarone remains one of the most effective antiarrhythmic drugs; however, its use is associated with a risk of amiodarone-induced thyroid dysfunction, including thyrotoxicosis and hypothyroidism. Thyroid dysfunction may worsen the course of cardiovascular disease and affect in-hospital prognosis. Despite the availability of clinical guidelines, data on the real-world incidence of amiodarone-induced thyroid dysfunction and its association with in-hospital outcomes remain limited. Aim: To evaluate the incidence of amiodarone-induced thyroid dysfunction, identify factors related to its presence, assess the relationship between thyroid dysfunction and cardiovascular complications and hospital mortality.

Material and Methods. A retrospective analysis was performed in 340 patients receiving amiodarone therapy during hospitalization. Age, sex, primary cardiac diagnosis, left ventricular ejection fraction, amiodarone dose, duration of therapy, thyroid status parameters, and in-hospital outcomes were evaluated. The presence of amiodarone-induced thyroid dysfunction was determined on the basis of a clinical diagnosis documented in the medical records. Group comparisons of quantitative and categorical variables, an additional Welch t-test, contingency table analysis, and binomial logistic regression were used.

Results. Amiodarone-induced thyroidopathy was detected in 40 out of 340 patients (11.8%). Age was associated with a higher odds ratio for thyroid disease (OR=1.12; 95% CI for OR 1.07–1.17; p < 0.001; approximately a threefold increase in the odds of developing thyroid disease over 10 years). A maintenance dose of amiodarone doubled the odds of a thyroid disorder diagnosis (OR=1.01 per 1 mg; 95% CI for OR 1.007–1.014; p=0.031); the dose of amiodarone received during hospitalization was not statistically significant. Left ventricular ejection fraction showed no association with the development of thyroidopathy. The presence of amiodarone-induced thyroidopathy was associated with a threefold increase in the odds of cardiac complications (OR=3.47; 95% CI 1.61–7.47; p=0.001). The association between thyroid dysfunction and in-hospital mortality was not assessed due to the low incidence of the event (1.18%, n=4).

Conclusion. Amiodarone-induced thyroid dysfunction develops in approximately one in nine patients receiving amiodarone therapy and is related to an adverse in-hospital course. Older age and a higher maintenance dose of the drug were related to a higher probability of detecting amiodarone-induced thyroid dysfunction. Differences in the dynamics of hormonal normalization confirm the heterogeneity of the pathogenesis of thyroidopathy, given that its development is not associated with systolic myocardial dysfunction. These data may serve as a basis for revising the management guidelines for patients taking amiodarone. The study results can be used to personalize thyroid function monitoring in older patients and when higher maintenance doses of amiodarone are used.

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