Functioning of thyroid hormones has a strong association with the risk of atrial fibrillation (AF), reveal scientists at Vanderbilt University Medical Center. AF is an irregular heart rhythm which increases the risk of heart-related complications and stroke.
The phenome-wide association study scanned the medical records of more than 37,000 people for an association between genetically determined variation in thyroid stimulating hormone levels (a measure of thyroid function) and AF risk.
Previous observational studies have found that subclinical hyperthyroidism, an overactive thyroid which does not meet the clinical threshold for diagnosis or treatment, nevertheless can increase the risk of AF. But whether to treat subclinical hypo- or hyperthyroidism to reduce AF risk remains a matter of debate in the medical community.
The decision to treat subclinical thyroid disease should account for this new evidence, as "antithyroid medications to treat hyperthyroidism may reduce AF risk (while) thyroid hormone replacement for hypothyroidism (low thyroid function) may increase AF risk," the researchers concluded.