Can thyroid disease increase the risk of Atrial fibrillation (Afib)? The answer is yes. Many studies show that thyroid disease (hyperthyroidism or hypothyroidism) can increase the risk of AFib. Luckily, both thyroid disease and atrial fibrillation are manageable if you notice the symptoms early and seek medical help. Learn how thyroid disease is connected to atrial fibrillation and the symptoms to look out for in this article. Get a consultation with the best cardiologists in Brooklyn.
How Often Do People Have AFib and Thyroid Disease?
While there is no exact figure that captures how many people live with both atrial fibrillation (AFib) and thyroid disease, multiple studies suggest that the connection is significant—especially in cases of hyperthyroidism. Individuals diagnosed with thyroid disease, particularly those with an overactive thyroid, face a markedly increased risk of developing AFib. This connection becomes even more pronounced with age, especially for those over 60 years old.
A 2015 study analyzing nearly 9,000 patients with AFib found that approximately 540 individuals also had hypothyroidism, while 141 had hyperthyroidism. Surprisingly, this data suggested a slightly higher presence of AFib among those with hypothyroidism, although the relationship between this type of thyroid disease and AFib remains unclear in broader research.
More recently, a 2022 study provided further insight, confirming that hyperthyroidism is a well-established risk factor for AFib. It found a clear incidence rate of 1.41% per person with hyperthyroidism developing AFib, reinforcing the idea that thyroid disease—specifically in its overactive form—can directly affect heart rhythm and increase cardiovascular complications.
However, the relationship between hypothyroidism and AFib remains more ambiguous. While some cases show overlap, the data does not yet support a consistent or direct link between low thyroid function and the onset of AFib. Despite this, researchers agree that thyroid disease, especially when untreated or poorly managed, can significantly impact overall heart health.
As AFib is the most common heart condition associated with thyroid disease, understanding this connection is crucial for early detection and prevention. Individuals with any form of thyroid disease should work closely with both their endocrinologist and cardiologist to monitor for signs of AFib and ensure optimal management of both conditions.
Link between thyroid disease and Atrial Fibrillation
Thyroid disease is a well-recognized contributor to various cardiovascular conditions, particularly atrial fibrillation (AFib). Among the different types of thyroid dysfunction, hyperthyroidism is most commonly and clearly linked with AFib. This condition arises when the thyroid gland becomes overactive and produces excessive amounts of thyroid hormones. These hormones stimulate the heart, increasing heart rate and potentially leading to irregular rhythms such as AFib, along with symptoms like palpitations and chest discomfort.
The relationship between thyroid disease and AFib becomes more complex when hypothyroidism—a condition where the thyroid produces insufficient hormones—is considered. Some researchers suggest that hypothyroidism may offer a slight protective effect against AFib, while others argue it may indirectly raise the risk. This discrepancy reflects the need for continued research and more nuanced understanding of how different thyroid imbalances affect heart health.
A key factor in this dynamic is thyroid-stimulating hormone (TSH). Produced by the pituitary gland, TSH regulates the thyroid’s production of hormones. Elevated TSH levels typically indicate hypothyroidism. A 2017 study found that increased levels of free thyroxine (fT4) in individuals with subclinical hypothyroidism were associated with a higher risk of AFib—highlighting that even subtle thyroid imbalances can impact heart rhythm.
Unmanaged or undiagnosed thyroid disease—especially hypothyroidism—can contribute to a range of cardiovascular issues, including:
- Increased diastolic blood pressure
- Heart failure due to weakened cardiac output
- Sinus bradycardia (abnormally slow resting heart rate)
Furthermore, a 2020 review revealed that elevated TSH levels, even among people with mild or subclinical hypothyroidism, were linked with higher all-cause mortality rates. This suggests that the effects of thyroid disease extend beyond hormone regulation—they can directly and indirectly affect heart health, circulation, and systemic inflammation.
In fact, several common risk factors for AFib are also associated with hypothyroidism, including:
- Obesity
- High blood pressure
- Type 2 diabetes
- Chronic inflammation
These overlapping conditions help explain why thyroid disease—particularly when undiagnosed—can play a hidden but significant role in cardiovascular health. Hypothyroidism may not always lead directly to AFib, but it can create the ideal environment for it by disrupting the heart’s electrical signaling, affecting vascular resistance, and altering cardiac output.
In 2019, research reinforced this broader understanding by showing that both elevated and suppressed thyroid hormone levels can aggravate heart-related disorders. These include:
- Atherosclerotic vascular disease
- Congestive heart failure
- Atrial and ventricular arrhythmias
- Dyslipidemia (abnormal lipid levels)
These findings affirm the importance of monitoring thyroid function, especially in individuals with existing cardiovascular risks or symptoms. Thyroid disease is not just a hormonal issue—it’s a systemic condition that can quietly influence heart rhythm, vascular health, and long-term outcomes. Early diagnosis, routine screening, and coordinated care between endocrinologists and cardiologists are essential in managing both thyroid health and its cardiac implications.
What are the symptoms to look for?
Recognizing the early symptoms of both thyroid disease and atrial fibrillation (AFib) is crucial for timely diagnosis and management. Since these two conditions can sometimes overlap or be mistaken for other health issues, it’s important to understand the warning signs of each.
Symptoms of Hyperthyroidism
Thyroid disease, particularly hyperthyroidism, occurs when the thyroid gland produces an excessive amount of thyroid hormones. This can overstimulate your body and heart. Common symptoms include:
- Feeling constantly nervous, anxious, or irritable, even without a clear cause
- A rapid or irregular heartbeat, sometimes described as racing or pounding
- Excessive sweating, even in cool environments
- Trouble sleeping or experiencing restlessness throughout the night
- Visible or palpable swelling in the neck, often due to an enlarged thyroid gland (goiter)
- Tremors or shakiness in the hands and fingers
- Muscle weakness or general fatigue, especially in the upper arms or thighs
- Unintentional weight loss despite normal or increased appetite
- Irregular menstrual cycles or lighter periods (in women)
In older adults, hyperthyroidism symptoms can be subtler. Instead of classic signs like nervousness or sweating, elderly individuals may present with depression, fatigue, poor appetite, and social withdrawal. These “masked” symptoms can delay diagnosis, allowing thyroid disease to silently impact heart health.
Symptoms of Atrial Fibrillation (AFib)
AFib, often associated with thyroid disease, particularly hyperthyroidism, is a type of irregular heartbeat that can lead to serious complications like stroke or heart failure. Its symptoms may vary from person to person, but common indicators include:
- A sensation that your heartbeat is out of rhythm — often described as racing, fluttering, or skipping
- Chest pain or discomfort, which may feel like pressure or tightness
- Feeling light-headed or faint, sometimes leading to actual fainting episodes
- Confusion or trouble concentrating, especially in older adults
- Persistent tiredness or weakness, even after minimal activity
- Shortness of breath, particularly during exertion or while lying flat
- Difficulty with physical activity due to fatigue or a feeling of being easily “winded”
- Unusual or excessive sweating not explained by physical exertion or heat
Because AFib can come and go (paroxysmal AFib), many people mistake its symptoms for stress, caffeine sensitivity, or general aging. However, when AFib is triggered by thyroid disease, it tends to be more persistent and potentially more dangerous if left untreated.
Why These Symptoms Matter
Recognizing the symptoms of thyroid disease and atrial fibrillation (AFib) is not just about identifying isolated health issues—it’s about understanding how these conditions are interconnected and can significantly affect one another. When left untreated, thyroid disease, particularly hyperthyroidism, can directly increase the risk of AFib. Elevated levels of thyroid hormones stimulate the heart, increasing its workload, which can lead to rapid, irregular electrical impulses in the heart’s upper chambers. This disruption is often what triggers AFib episodes.
Likewise, atrial fibrillation can complicate the management of thyroid disease. For example, AFib may mask common thyroid-related symptoms such as fatigue or irregular heart rate, making it more difficult to identify the underlying hormonal imbalance. This interplay can lead to delayed diagnosis and treatment, which may increase the risk of more serious cardiovascular events like stroke or heart failure.
Even in cases of hypothyroidism, where the thyroid produces too little hormone, the resulting changes in blood pressure, cholesterol levels, and vascular function can indirectly contribute to heart rhythm disturbances. While the connection between hypothyroidism and AFib is more complex and less direct, ongoing studies suggest that long-term untreated thyroid disease can still impact heart health through multiple pathways.
Because of this bidirectional relationship, paying close attention to these overlapping symptoms is vital. People with a known family history of thyroid disease or cardiac arrhythmias should be particularly vigilant. Symptoms like palpitations, fatigue, shortness of breath, unexplained weight changes, or neck swelling should not be ignored.
Early intervention makes a significant difference. If you’re experiencing any combination of these signs, it’s essential to speak with a healthcare provider who can evaluate you for both thyroid disease and AFib. Diagnostic tools such as blood tests to measure thyroid hormone levels (TSH, T3, T4), electrocardiograms (EKGs) to assess heart rhythm, and imaging like echocardiograms or thyroid ultrasounds can help determine the root cause of your symptoms and guide appropriate treatment.
Proactive monitoring and integrated care are crucial when dealing with thyroid disease and heart conditions simultaneously. Addressing both issues early can help restore normal rhythm, balance hormone levels, and greatly reduce the risk of long-term complications.
When to see your doctor?
You should see your doctor if you have symptoms of AFib or hyperthyroidism. It might be something else completely, but this will be helpful to know for sure. If you have chest pain along with other symptoms, then you should go to the emergency room because it can be a sign of a heart attack.
Thyroid disease and atrial fibrillation (AFib) are connected because thyroid disease can increase the risk of atrial fibrillation by either impacting the heart and blood vessels directly or increasing other risk factors that indirectly increase the risk of atrial fibrillation. Fortunately, these conditions are treatable and manageable by noticing their symptoms and seeking treatment.
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