Researchers in Denmark examined the correlation between hyperthyroidism and atrial fibrillation (AF), the most common cardiac arrhythmia, in patients admitted to the hospital with new-onset AF. Traditionally, hyperthyroidism has been shown to be a risk factor for AF. However, in a new study spanning 13 years of data collection, researchers aimed to see whether new-onset AF is a predictor of late-occurring hyperthyroidism. Researchers theorized that since hyperthyroidism symptoms often develop slowly and may present as non-specific, a presentation of AF may be the first clinical sign of thyroid dysfunction.
From 1997 through 2009, a total of 145,623 patients with new-onset AF who were admitted to the hospital were included in the nationwide cohort study. Patients were excluded if they had previous histories of thyroid diagnosis or thyroid medication. Mean age was 66.4 years (SD ± 13.2; 55.3% men) and of those patients examined, 3% (4,620 events; 62.2% women) developed hyperthyroidism during post-hospitalization. This was compared to 1% (48,609 events; 82% women) of the general population (n=3,866,889).
Researchers found that, when comparing the study cohorts to the general population, there was a twofold-increased risk of hyperthyroidism, in both men and women alike, for those with new-onset AF. A follow-up thyroid screening of 527,352 patients further confirmed the results. Researchers also found that middle-aged men who presented with new-onset AF demonstrated the highest risk for hyperthyroidism. This risk consistently increased throughout the 13-year examination period.
Investigators have demonstrated that new-onset AF can be considered as a predictor of subsequent hyperthyroidism in both men and women. Further investigation and increased focus on the correlation between new-onset AF and late-occurring hyperthyroidism is suggested. This also shows potential value in follow-up assessment of thyroid status in new-onset AF patients.