Atrial fibrillation and low-normal TSH-value:is there a link?

Abstract Non valvular atrial fibrillation (AF) is the most common ar-rhythmia in Internal Medicine Departments (IMD). Pathologic altera-tions of thyroid function have already been associated to an increased risk of AF. We evaluated if even among euthyroid patients lower TSH values could be associated to an increased prevalence of AF.Methods We retrospectively evaluated 493 consecutive patients af-fected by AF admitted to our department who underwent to a completethyroid function evaluation. Patients with hyperthyroidism (TSH<0.1 mU/l) or hypothyroidism (TSH>3.5mU/l) were excluded. We obtained 3 groups (group 1:0,1-1,2mU/l; group 2:1,2-2,3mU/l; group 3:2,3- 3,5mU/l). r2-test was used to evaluate difference in distributions,t-test for was used to assess differences among continuous variables.Results 419 euthiroid patients were eligible for analysis. Mean TSH values(F:1,53±0,87 mU/l; M:1.38±0.77 mU/l) weren’t statistically different between sexes. We observed a statistically significant differ-ence in distribution of AF: most of the patients were in group 1 (47% of the AF cases), less was observed in group 2 (36%) and 3 (16%). Discussion: TSH, even in its low-normal range, could mark a population at higher risk for AF. Larger and perspective studies should be obtained in order to validate this observation.