US Pharm. 2019;44(2):HS-6-HS-8.

A study by researchers at Vanderbilt University Medical Center has solidified the link between thyroid function and atrial fibrillation (AFib), an irregular heart rhythm that increases the risk of stroke and other heart-related complications.

The phenome-wide association study scanned the medical records of more than 37,000 people for a link between genetically programmed variation in thyroid-stimulating hormone levels and AFib risk.

Earlier observational studies found that subclinical hyperthyroidism, an overactive thyroid that does not meet the clinical threshold for diagnosis or treatment, can still increase the risk of AFib. Whether to treat subclinical hypo or hyperthyroidism to reduce AFib risk, however, remains in debate in the healthcare community.

Published recently in the journal JAMA Cardiology, Vanderbilt scientists found that genetically determined variations in thyroid function, even those that fall within a physiologically accepted range, still can increase the risk for AFib.

The decision to treat subclinical thyroid disease should account for this new evidence, as “antithyroid medications to treat hyperthyroidism may reduce AFib risk (while) thyroid hormone replacement for hypothyroidism (low thyroid function) may increase AFib risk,” the researchers said.