The outcomes of thyrotoxicosis related new-onset atrial fibrillation

Abstract

INTRODUCTION: Although thyrotoxicosis (TT) is a common cause for atrial fibrillation (AF), the clinical outcomes of TT related new onset persistent AF remains unclear. METHODS AND RESULTS: Over 10-year period, 215 patients (pts) with TT with new onset-AF were studied. 15 pts with pre-existing heart diseases were excluded. Among 200 pts with TT related AF, their mean age was 64±17 years (41% male). At presentation, 14 pts (7%) had concomitant ischemic stroke (IS) and 77 pts (39%) developed congestive cardiac failure (CCF). Pts with IS had a higher prevalence of hypertension (HT) than those without IS (50 vs. 25%,p=0.04), but had no difference in age and sex (p>0.05). After mean follow-up of 45±37 months, 100 pts (50%) had spontaneous cardioversion (CV) at median time of 23 days. The median time to euthyroidism with anti-thyroid drug was 81 days. In univariate analysis, there were no significant differences in pts with or without CV with respect to age, male gender and diabetes (Table). However, pts without CV had a higher prevalence of HT and CCF at the time of presentation, lower usage of beta-blockers, larger left atrial (LA) and left ventricular (LV) size, and lower ejection fraction (EF) than those with CV (Table, P<0.05). Multivariate analysis demonstrated only LA is the independent predictor for CV (OR=3.9, P=0.01). CONCLUSION: TT related AF is related to high incidence of IS and CCF at presentation. After control of TT, spontaneous CV can occur in up to 50% pts. The sole independent predictors of CV is smaller LA.