Post-Cardiac Transplant Lymphocytic Thyroiditis Secondary to Amiodarone Use in the Pre-Transplant Period

Purpose Amiodarone is a commonly used anti-arrhythmic medication for atrial and ventricular arrhythmias in end-stage heart failure. Due to heavy iodine content, amiodarone is implicated in a variety of thyroid disorders, which could lead to adverse outcomes in cardiac transplant (CT) patients. Data on the development of post-CT lymphocytic thyroiditis (LT) in patients with pre-CT amiodarone use is limited. We aimed to study the development of amiodarone-induced LT in CT patients in a tertiary care transplant center in the United States. Methods We retrospectively reviewed medical records of patients who underwent CT from 03/2010 to 10/2018 (N=137) at our center. 11 patients were excluded (10 = lack of pre-CT records, 1 = pre-transplant LT). The final cohort (N=126) was divided into two groups- those who developed post-CT LT vs. those who didn't. Baseline characteristics were compared between the groups, and predictors of post-CT LT were identified using regression modeling on Stata 15.0. Results Mean age of the cohort was 55.9 years, 80 % were men and 89 % were Caucasians. Incidence of post-CT LT was 10.3 % and mean time from transplant to the diagnosis of LT was 26.9 months. Patients who developed LT were similar in demographics as well as clinical characteristics but had significantly higher use of amiodarone (53.8 % vs 25.7 %, p=0.03), higher dose of amiodarone (343 mg vs 252 mg, p=0.049) and lower left ventricular ejection fraction (LVEF) (10.9 % vs 16.6 %, p=0.03) before transplant (Table 1). On univariate regression analysis, use of amiodarone [OR (p) = 3.4 (0.04)], African-American race [OR (p) = 4.4 (0.05)] and lower LVEF [OR (p) = 0.89 (0.046)] predicted post-CT LT. Conclusion To our knowledge, this is the first study examining the incidence of post-CT LT secondary to amiodarone use in the pre-transplant period. The incidence of LT in our study was 10.3 % and was associated with pre-transplant amiodarone use, underpinning the importance of recognizing this side effect of amiodarone in the post-CT period.