A Comparative Analysis of TSH Levels between Patients with Normal Sinus Rhythm and those with Atrial Fibrillation

Atrial Fibrillation (AF) is the most prevalent persistent cardiac arrhythmia observed within the general population and is associated with increased morbidity and mortality. Despite the rising global prevalence of AF, the majority of existing studies have primarily focused on white populations. For that reason, we have used a Korean hospital patient's blood test results to examine the link between AF and certain blood test results. Conducted at a tertiary medical institution, this retrospective study included patients with Normal Sinus Rhythm (NSR) and AF, excluding those on thyroid medications at diagnosis. Initially, 200 patients were evaluated, with 36 excluded, leaving 164 for the final analysis. In the NSR group, the average Thyroid Stimulating Hormone (TSH) level was 1.88 (normal range: 0.41-4.3 uIU/mL), with a standard deviation of 1.27. In the AF group, the average TSH level was 2.48, with a standard deviation of 1.91 (p = 0.018). AF was associated with both hyperthyroidism and hypothyroidism, which appeared to be a common precursor of thyroid dysfunction. The study highlights clinical risk factors for thyroid dysfunction in AF patients, despite limitations such as a small sample size and potential detection bias due to unrecognized new-onset AF