Amiodarone therapy before heart transplantation as a predictor of thyroid dysfunction after transplantation

Background: In recent years we have observed new cases of thyroid disease occuring after heart transplantation. (HTx). In these patients, the presence of this disease complicates their post-transplant course and occasionally results in life-threatening thyrotoxicosis. The present study examines the incidence and risk factors of thyroid disease in these patients with special emphasis on the use of amiodarone before HTx. Recommendations for follow-up of thyroid disease in HTx patients are discussed. Methods: A study was performed on a cohort of 380 patients who received HTx in Rotterdam between January 1, 1985 and April 1, 2001. Twenty patients (5%) developed thyroid dysfunction after HTx, 10 of whom had been treated with amiodarone before HTx. Results: Cumulative survival curves showed that most patients (60%) developed thyroid dysfunction within the first year after HTx (median interval between HTx and diagnosis was 9 months). Using univariate Cox regression analysis, amiodarone was a significant predictor for the development of thyroid dysfunction (hazards ratio 5.2, 95% confidence interval 2.5 to 10.8). After adjustment for age, gender, heart disease and Quetelet index, amiodarone remained a significant predictor. Conclusions: Our study clearly shows that, despite discontinuation of amiodarone treatment at the time of the HTx procedure, patients remain at risk for developing thyroid disease. HTx recipients treated with amiodarone before HTx should therefore be monitored carefully for development of thyroid dysfunction, especially within the first post-transplant year.