The connection between overt hyperthyroidism and atrial fibrillation is well known, but there isn’t much evidence on whether milder hyperthyroidism is associated with an irregular heartbeat. Furthermore, irregular heartbeat and hypothyroidism also has very limited data available.
A Denmark-based research team aimed to examine any possible link between atrial fibrillation in a wide spectrum of thyroid disorders.
The researchers used nationwide data and identified 586,460 patients who underwent thyroid function blood tests. They looked at levels of the thyroid-stimulating hormone within the blood. In people with hyperthyroidism, the levels would be low, and in hypothyroidism the levels would be high.
After an average of a five-year follow-up period, three percent of patients had a diagnosis of atrial fibrillation. Compared with normal patients without thyroid problems, the risk of atrial fibrillation increased with decreased level of thyroid-stimulating hormone in the blood. For example, patients with hyperthyroidism had a 30 percent increase of atrial fibrillation, compared with only 12 percent in normal-functioning thyroids.
Hypothyroidism, on the other hand, was associated with a decreased risk of atrial fibrillation.
Although the researchers could not determine cause and effect, they do recommend heart monitoring for patients with hyperthyroidism.
Atrial fibrillation risk factors other than overactive thyroid gland
Aside from an overactive thyroid, there are many other risk factors that contribute to atrial fibrillation, including:
Age: The older a person is, the higher the risk of atrial fibrillation they face. Studies show, 10 to 20 percent of seniors will be diagnosed with atrial fibrillation by the age of 80.
Heart disease: If a person has heart disease or other issues with their heart, this too can increase their risk of atrial fibrillation.
High blood pressure: Hypertension is the most common risk factor for atrial fibrillation, and one in three Americans currently have hypertension. High blood pressure puts added stress onto the heart, thus contributing to a higher risk of atrial fibrillation.
Alcohol consumption: Alcohol is a stimulant, similar to caffeine, and although it won’t lead to an irregular heartbeat all of the time, it is still a common risk factor. Heavy alcohol consumption or binge drinking are more closely related to atrial fibrillation.
Family history: If you have a family history of atrial fibrillation, this can contribute to your own risk of an irregular heartbeat. Some studies have shown that 30 percent of individuals with a family history of atrial fibrillation will develop it themselves.
Sleep apnea: An association has been seen between sleep apnea and atrial fibrillation, but why or how is still unclear. Sleep apnea can increase the risk of hypertension and even heart disease, and that may be the link between the two conditions.
Atrial fibrillation and hyperthyroidism treatments
Atrial fibrillation and hyperthyroidism treatments include:
- Anticoagulants (blood thinners) to reduce the risk of stroke in case there is a blood clot
- Medications to slow down the heart rate
- Beta blockers and calcium channel blockers to improve symptoms
- Anti-thyroid medications and radioactive iodine to treat hyperthyroidism
Your doctor will decide which mode of treatment is best for you to control and treat atrial fibrillation.