Analysis Of The Incidence And Risk Factors Of Thyroid Dysfunction In Patients With Atrial Fibrillation Caused By Amiodarone And The Safety And Efficacy Of Early Catheter Radiofrequency Ablation

Background: Amiodarone is frequently used to control atrial fibrillation and to maintain sinus rhythm,use of amiodarone may lead to abnormal thyroid function,including amiodarone-induced thyrotoxicosis(AIT)and amiodarone-induced hypothyroidism(AIH).Objective: The purpose of the study was to investigate the prevalence and the predictive factors for AIT and AIH of the patients treated with amiodarone,and to investigate the safety and efficacy of early radiofrequency catheter ablation in patients with paroxysmal AF complicated with AIT and AIH.This study was divided into two parts.Part 1: the prevalence and the risk factors for AIT and AIH of the patients with AFMethods: From January 2013 to June 2016,867 consecutive single-center patients with AF treated with amiodarone were recruited in the study.The baseline characteristics was collected,Baseline characteristics were compared between patients with AIT and with normal thyroid function,and patients with AIH and with normal thyroid function too.Cox proportional hazard regression analysis was used to identify the risk factors of the patients with AF treated with amiodarone.Results: AIT was induced in 50 patients(5.8%),AIH was induced in 94(10.8%)patients.Before taking amiodarone,the level of ATPO of AIT group is higher than that of control group(P=0.031);the level of TG-Ab of AIT group is higher than that of control group(P=0.045);and the proportion of patients with goiter is higher than that of control group(P=0.002).Cox proportional hazards regression analysis identified the positive of ATPO(P=0.033,HR:4.130,95%CI=1.418-9.619)and the goiter before taking amiodarone(P=0.008,HR:7.538,95%CI=2.325-32.106)as the independent risk factors for AIT.After discontinuation of amiodarone,atrial fibrillation burden was increased significantly(P=0.01).Before taking amiodarone,The level of ATPO(P=0.136),TG-Ab(P=0.637)and the proportion of patients with goite(P=0.183)was similar between AIH and control groups.There was no significant independent predictor for AIH in the Cox proportional hazards regression analysis.After discontinuation of amiodarone,atrial fibrillation burden was increased(P=0.05).Conclusions: In this study,the incidence of AIT is 5.8%,Cox proportional hazards regression analysis identified the positive of ATPO and the goiter before taking amiodarone as the independent risk factors for AIT.The incidence of AIH is 10.8%,there was no significant independent predictor for AIH in the Cox proportional hazards regression analysis.The atrial fibrillation burden was increased in patients with AIT and AIH.Part 2:Safety and efficacy of early radiofrequency catheter ablation in patients with paroxysmal atrial fibrillation complicated with amiodaroneinduced thyroid dysfunctionMethods: From the 867 consecutive patients with AF who had been treated with amiodarone at our center from January 2013 to June 2016,292 patients with paroxysmal AF underwent pulmonary vein isolation(PVI),of them,40 had developed AIT.60 controls with normal thyroid function and matched for baseline characteristics were selected randomly,47 had developed AIH.43 controls with normal thyroid function and matched for baseline characteristics were selected randomly.30 minutes after PVI,isoproterenol was given via intravenous drip to observe the occurrence of atrial fibrillation,atrial flutter and atrial tachycardia and recovery of conduction(Ro C)of pulmonary vein potential.The operation time,the X-ray exposure time,the Ro C and the complications were compared in the two groups.All the patients were followed up until 12 months after the operation.Results: PVI was completed in all the patients without serious complications and with similar procedural(P=0.062)and X-ray exposure(P=0.058)time in AIT vs.control groups;There were 2 patients with recovery of conduction(Ro C)of pulmonary vein were treated with re-PVI in 30 minutes after PVI.all patients received intravenous injection of isoproterenol 30 minutes post PVI,the recovery of conduction of PV potential(P=0.191).Upon coronary sinus catheter pacing(from 300 to 200ms),rates of induction of AF(P=0.005)and of non-PV-related atrial tachyarrhythmias(P=0.01)were higher.In AIT vs.control group,ATs recurrence rate was higher at 3 months(45% vs.16.67%,P=0.032)but not between 3 and 12 months(30% vs.23.33%;P=0.418)follow-up.PVI was completed in all the patients with similar procedural(p=0.271)and X-ray exposure(p=0.158)time in AIH vs.control groups;No patients had recovery of conduction(Ro C)of pulmonary vein in 30 minutes after PVI in AIH and control groups.All patients received intravenous injection of isoproterenol 30 minutes post PVI,the recovery of conduction of PV potential(P=0.096).Upon coronary sinus catheter pacing,rates of induction of AF(P=0.235)and of non-PV-related atrial tachyarrhythmias(P=0.537),those for typical atrial flutter(P=0.914)and atrial tachycardia(P=0.418)were similar in AIH and control group.The early ATs recurrence rate at 3 months P=0.751)and later ATs recurrence rate at 12 months(P=0.728)post ablation was similar during follow-up.Conclusions: Early catheter ablation for paroxysmal atrial fibrillation in patients with AIT appeared safe and effective albeit with higher ATs recurrence rate up to 3 months but not beyond up to 12 months after PVI relative to controls.Early Catheter ablation for paroxysmal atrial fibrillation in patients with AIH was safe and effective.PVI was completed in all the patients without serious complications.There was no statistically significance in the early recurrence at 3 months and later recurrence rate at 12 months post ablation in the two groups during follow-up.