title: Results of preventive radioiodine therapy in euthyroid patients with history of hyperthyroidism prior to administration of amiodarone with permanent atrial fibrillation--a preliminary study.
abstract: BACKGROUND
  Radioiodine (RAI) therapy is a standard procedure in the treatment of hyperthyroidism. However, the use of RAI in euthyroid patients requiring chronic administration of amiodarone (AM) where other antiarrhythmic drugs may lack efficacy is still controversial.
  
  
  OBJECTIVE
  The aim of this study was to assess the safety and efficacy of an AM therapy prior to treatment with radioiodine therapy in euthyroid patients with permanent atrial fibrillation (PAF), who had been treated for hyperthyroidism in the past.
  
  
  METHODS
  This was a retrospective observational study. Patients were assessed at baseline and two, six, eight, and 12 months after RAI therapy. 17 euthyroid patients with PAF were qualified to the RAI (female/male 3/14; age range 65 to 87, median 71). The patients required chronic administration of AM as a prophylaxis against sudden death.
  
  
  RESULTS
  Each patient received an ablative dose of 800 MBq (22 mCi) of 131I. At baseline and during follow-up, no side effects of the therapy and no signs of drug intolerance were observed. Subclinical hyperthyroidism occurred in two (11.8%) cases after two months of RAI and five weeks of AM administration. In this situation, RAI therapy was repeated. Three patients (17.6%) after six months, and another two (11.8%) after eight months, required an additional dose of 131I due to amiodarone-induced thyrotoxicosis (AIT). Twelve patients (70.6%) returned to spontaneous sinus rhythm within two months. Fourteen patients (82.4%) had sinus rhythm during follow-up after six and 12 months of treatment.
  
  
  CONCLUSIONS
  Preventive RAI in euthyroid (but previously hyperthyroid) patients with PAF before administration of AM may be the method of choice. This is particularly important for patients who will require permanent AM administration as a life-saving drug.
authors.affiliation: agata.rat@wp.pl.
authors.forename: Agata
authors.initials: A
authors.lastname: Czarnywojtek
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Zgorzalewicz-Stachowiak
authors.forename: Kosma
authors.initials: K
authors.lastname: Woliński
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Płazińska
authors.forename: Izabela
authors.initials: I
authors.lastname: Miechowicz
authors.forename: Barbara
authors.initials: B
authors.lastname: Kwiecińska
authors.forename: Rafał
authors.initials: R
authors.lastname: Czepczyński
authors.forename: Leszek
authors.initials: L
authors.lastname: Królicki
authors.forename: Marek
authors.initials: M
authors.lastname: Ruchała
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000638:Amiodarone / Q000627:therapeutic use*; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use*; D001281:Atrial Fibrillation / Q000188:drug therapy* / Q000503:physiopathology; D004305:Dose-Response Relationship, Drug; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007037:Hypothyroidism / Q000150:complications / Q000188:drug therapy* / Q000517:prevention & control; D007457:Iodine Radioisotopes / Q000009:adverse effects / Q000627:therapeutic use*; D008297:Male; D012189:Retrospective Studies
chemical_list: D000889:Anti-Arrhythmia Agents; D007457:Iodine Radioisotopes; D000638:Amiodarone