Can Thyroid Problems Cause Atrial Fibrillation (AFib)?

One question patients frequently ask is:

"Can my thyroid cause atrial fibrillation?"

The simple answer is yes.

Both an overactive thyroid (hyperthyroidism) and, less commonly, an underactive thyroid (hypothyroidism) can contribute to atrial fibrillation (AFib).

Understanding the connection between your thyroid gland and your heart is important because treating thyroid disease is often a key part of successfully managing atrial fibrillation.

According to Professor Malcolm Finlay, consultant cardiologist and heart rhythm specialist, thyroid disorders should always be considered when investigating a patient with AF.

Key Takeaways

• The thyroid gland produces hormones that regulate the body's metabolism.

• Thyroid hormones have a direct effect on the heart and its electrical system.

• An overactive thyroid is a well-recognised cause of atrial fibrillation.

• An underactive thyroid can also contribute to AF, although this is less common.

• Thyroid disorders should be identified and treated alongside atrial fibrillation.

• Correcting thyroid function alone does not always eliminate AFib.

• Patients often require treatment for both their thyroid condition and their atrial fibrillation.

  
  

What Is the Thyroid Gland?

The thyroid gland is a small butterfly-shaped gland located at the front of the neck.

What does the thyroid do?

The thyroid produces hormones called:

• T3 (Triiodothyronine)

• T4 (Thyroxine)

These hormones regulate the body's metabolism by controlling how much energy cells use throughout the body.

Because the heart is one of the body's most metabolically active organs, it is particularly sensitive to changes in thyroid hormone levels.

How Does the Thyroid Affect the Heart?

Why do thyroid hormones affect heart rhythm?

Thyroid hormones influence:

• heart rate

• electrical conduction

• heart muscle activity

• the way heart cells communicate with each other

When thyroid hormone levels become abnormal, the electrical system of the heart can also become abnormal, increasing the risk of arrhythmias such as atrial fibrillation.

Can an Overactive Thyroid Cause AFib?

What is hyperthyroidism?

Hyperthyroidism occurs when the thyroid gland produces too much thyroid hormone.

This causes the body's metabolism to speed up.

How does hyperthyroidism trigger atrial fibrillation?

An overactive thyroid makes the cells in the atria more electrically active.

At the same time, it can encourage the development of small amounts of fibrous tissue between heart muscle cells.

These changes make it easier for abnormal electrical impulses to develop, increasing the likelihood of atrial fibrillation.

One of the strongest associations is seen with thyrotoxicosis, where thyroid hormone levels become significantly elevated.

Can an Underactive Thyroid Cause AFib?

What is hypothyroidism?

Hypothyroidism occurs when the thyroid gland produces too little thyroid hormone.

Although less commonly associated with AFib than hyperthyroidism, it can still contribute to rhythm disturbances.

Why can hypothyroidism lead to AF?

Lower thyroid hormone levels may:

• slow electrical conduction through the atria

• increase fibrous tissue between heart cells

• alter the heart's normal electrical pathways

These changes can also increase the risk of atrial fibrillation in some patients.

Which Thyroid Condition Is More Likely to Cause AF?

Hyperthyroidism is by far the more common cause.

When thyroid hormone levels are too high, heart cells become more electrically excitable, making atrial fibrillation much more likely.

Hypothyroidism can contribute, but this is seen much less frequently.

Should Thyroid Problems Be Treated Before AF?

Which condition should be treated first?

Ideally, any thyroid disorder should be identified and treated before or alongside treatment for atrial fibrillation.

Managing thyroid hormone levels helps create the best possible environment for successful AF treatment.

However, Professor Malcolm Finlay explains that it is often appropriate to treat both conditions at the same time, particularly if atrial fibrillation is causing significant symptoms.

Will Treating the Thyroid Cure AFib?

This is one of the biggest misconceptions.

If my thyroid is corrected, will AF disappear?

Not necessarily.

Although thyroid disease may trigger atrial fibrillation, many patients already have an underlying tendency to develop AF.

The thyroid problem simply pushes them beyond the point where atrial fibrillation develops.

Even after thyroid hormone levels return to normal, atrial fibrillation may continue and require its own treatment.

This is why managing AF often involves:

• medications

• cardioversion

• catheter ablation

• lifestyle changes

• ongoing rhythm management

rather than relying solely on thyroid treatment.

How Is AF Related to Thyroid Disease Treated?

Treatment is tailored to each individual patient.

Management may include:

Treating the thyroid condition

This may involve medication or specialist endocrine treatment to restore normal hormone levels.

Managing stroke risk

Blood-thinning medication may be recommended where appropriate to reduce the risk of stroke.

Controlling heart rate or rhythm

Treatment may include:

• beta blockers

• anti-arrhythmic medication

• electrical cardioversion

• catheter ablation

The most appropriate treatment depends on symptoms, underlying heart health and the type of atrial fibrillation.

Frequently Asked Questions About Thyroid Disease and AFib

Can thyroid problems cause atrial fibrillation?

Yes. Both overactive and underactive thyroid disorders can increase the risk of AFib, although hyperthyroidism is the more common cause.

Can an overactive thyroid cause AF?

Yes. High thyroid hormone levels make heart cells more electrically active, increasing the likelihood of atrial fibrillation.

Can hypothyroidism cause AFib?

Yes, although it is much less common than with hyperthyroidism.

Will treating my thyroid stop AFib?

Not always. Many patients still require separate treatment for atrial fibrillation after thyroid hormone levels have been corrected.

Should thyroid function be checked in patients with AF?

Yes. Thyroid blood tests are an important part of investigating newly diagnosed atrial fibrillation.

Can AF ablation still be needed if thyroid disease caused my AF?

Yes. If atrial fibrillation persists after thyroid treatment, catheter ablation or other rhythm control treatments may still be appropriate.

If you've been diagnosed with atrial fibrillation and have concerns about how a thyroid condition may be affecting your heart rhythm, Professor Malcolm Finlay provides expert assessment and personalised treatment for both newly diagnosed and complex AF.

Understanding the underlying cause of your atrial fibrillation is key to choosing the most effective treatment plan.

Website: https://www.drmalcolmfinlay.com/

Telephone: 0207 183 0514

Email: pa@drmalcolmfinlay.com