A study of more than 586,000 Danes showed that those with overactive thyroid (hyperthyroidism) are at increased risk for atrial fibrillation, a common cardiac arrhythmia (irregular heartbeat).
Between 2000 and 2010, the subjects had undergone a thyroid function blood test. During an average 5.5 years of follow-up, 3 percent of the patients were diagnosed with atrial fibrillation and 53 percent of those patients were women, the HealthDay reports.
The researchers — led by Christian Selmer of Gentofte University Hospital, in Hellerup, Denmark — found that compared to patients with normal thyroid function, those with early stage hyperthyroidism had a 30 percent increased risk of atrial fibrillation, while those with high-normal thyroid function had a 12 percent increased risk.
Selmer and colleagues said their findings highlight the importance of long-term screening for atrial fibrillation in people with hyperthyroidism.
However, for Dr. Sripal Bangalore, an assistant professor in the department of medicine at NYU Langone Medical Center who was not involved in the study, more studies are still needed to determine the causal association between thyroid activity and atrial fibrillation and identify the next step.
On the other hand, Dr. Suzanne Steinbaum, a preventive cardiologist at Lenox Hill Hospital in New York City, also not involved in the study, agreed with the authors that evaluating early hyperthyroidism “is essential to adequately assess the risk for atrial fibrillation [in patients] and to treat it before it becomes a cardiac issue.”