What to know about hyperthyroidism and congestive heart failure

What is the link between hyperthyroidism and heart failure?

The thyroid gland helps regulate many processes in a person’s body. This includes heart rate. Changes in the levels of thyroid hormones can cause a person’s heart rate to increase or decrease.

If a person has hyperthyroidism, these hormones may signal the heart to beat too fast. This may cause a person to develop a rapid and irregular heartbeat.

A review from 2023Trusted Source stated that hyperthyroidism can lead to thyrotoxicosis, which may cause symptoms such as:

• increased cardiac output, which is the amount of blood the heart pumps in a minute
• increased systolic blood pressure, which is the force of blood pushing against the artery walls as the heart beats
• rapid heart rate
• irregular heartbeat

Researchers note that these symptoms may cause heart failure, which can be fatal.

Another 2023 review lists thyrotoxicosis as a rareTrusted Source cause of congestive heart failure. Researchers state that this may be due to a fast, irregular heartbeat and increases in blood volume caused by hormonal changes.

A review from 2017Trusted Source noted that untreated hyperthyroidism and high cardiac output may cause the left ventricle of the heart to become enlarged. The left ventricle is the main pumping chamber of the heart. It can become enlarged and weakened if a person has heart failure.

Other causes of congestive heart failure

The American Heart Association (AHA)Trusted Source notes that other potential causes of heart failure include:

• previous heart attack
• abnormal heart valves
• cardiomyopathy
• myocarditis
• congenital heart disease
• arrhythmia
• severe anemia

The National Heart, Lung, and Blood Institute (NHLBI)Trusted Source lists the following as risk factors for heart failure:

• being 65 years old or over
• family history of heart failure
• smoking cigarettes
• eating an unhealthy diet
• heavy alcohol intake
• taking recreational drugs
• lack of exercise
• atrial fibrillation, a type of arrhythmia
• heart or blood vessel disease, severe lung disease, or infections like HIV or SARS-CoV-2
• other long-term conditions, including:
  • obesity
  • high blood pressure
  • sleep apnea
  • diabetes
  • chronic kidney disease
  • iron overload
• having cancer treatments, such as chemotherapy or radiation therapy
• having Black or African American heritage

Diagnosing congestive heart failure

A doctor may diagnose heart failure using several methodsTrusted Source. These may include asking a person about their medical and family history. A doctor may also perform a physical examination and certain tests, which we explore in more detail below.

Blood tests

A doctor may take a sample of a person’s blood and send it to a laboratory. Laboratory technicians can look at a person’s blood and check the levels of certain molecules, like brain natriuretic peptide. These levels may increase if a person has heart failure.

Imaging tests

A doctor may request echocardiography to check a person’s ejection fraction. This is the percentage of the blood in the left ventricle that is pumped out during every heartbeat. A doctor may also request a CT scan, MRI, nuclear heart scan, or coronary angiography. These tests allow a doctor to see images of a person’s heart.

Other tests

A doctor may also measure a person’s heart rate using an EKG. Additionally, they may ask a person to wear a heart monitor for 24 to 48 hours. A doctor may also use a stress test to see how a person’s heart works during physical activity.

Treating congestive heart failure

The NHLBI notes that there is no cureTrusted Source for heart failure. However, there are treatments available that may help manage symptoms. These include:

• reducing sodium intake
• maintaining a moderate weight
• exercising regularly
• quitting smoking, if applicable
• limiting or avoiding alcohol
• managing other underlying conditions where possible
• getting good-quality sleep
• managing stress

A doctor may also prescribe certain medications to treat a person’s heart failure, such as:

• diuretics and aldosterone antagonists, which remove extra sodium and fluid from the body
• angiotensin converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) to relax blood vessels
• beta-blockers and ivabradine, which slow heart rate
• sodium-glucose cotransporter-2 (SGLT-2) inhibitors to lower blood sugar, blood pressure, and more
• glucagon-like peptide (GLP) agonists to reduce blood sugar, the risk of heart attack, and more
• digoxin, which helps improve heartbeat strength

The exact treatment will vary depending on each individual.

When to speak with a doctor

The AHATrusted Source states that a person should speak with their doctor if they experience any of the following signs of heart failure:

• dry, hacking cough
• worsening shortness of breath during activity
• increased swelling in ankles, feet, or legs
• sudden weight gain of more than 2 to 3 pounds (lb) in a day, or 5 lb in a week
• discomfort or swelling in the abdomen
• difficulty sleeping

A person should seek immediate medical attention if they experience any of the following:

• frequent dry, hacking cough
• shortness of breath at rest
• increased swelling or discomfort in the lower body
• new or worsening dizziness, confusion, sadness, or depression
• loss of appetite
• increased difficulty sleeping
• inability to lie flat

Summary

Research indicates that there may be a link between hyperthyroidism and congestive heart failure. If hyperthyroidism progresses to thyrotoxicosis, it can cause symptoms that increase the risk of heart failure.

Without treatment, heart failure can be fatal. If a person notices any sudden or severe signs of heart failure, they should seek immediate medical attention.