Thyroid hormones reduce animal cardiac arrhythmias

December 10, 2014, New York Institute of Technology

Rats that received thyroid hormones had a reduced risk for dangerous heart arrhythmias following a heart attack, according to a new study by a team of medical researchers at New York Institute of Technology.

In the NIH-funded study, published in the Journal of Cardiac Failure, the team found that thyroid significantly reduced the incidence of atrial fibrillation - a specific kind of irregular heartbeat, or arrhythmia—in the rats, compared to a control group that did not receive the hormones.

The finding could have important implications for future treatment of human patients, says lead researcher Youhua Zhang, MD, Ph.D., noting that up to about half of the humans with also suffer from atrial fibrillation.

"Our data highlights the potential clinical importance of correcting to prevent cardiac arrhythmias and in heart failure," Zhang and the researchers wrote in their study. "In other words, withholding thyroid hormone treatment in heart failure may do harm when cardiac hormone levels are below normal."

Zhang said researchers induced heart attacks in a group of 29 rats. Fourteen were treated with a form of thyroid hormone known as T4. After two months of treatment, the researchers measured cardiac function and then attempted to induce rapid and irregular heartbeats. Eleven of the 15 animals in the control group developed the arrhythmia but only four of the 14 animals treated with the thyroid hormone developed an arrhythmia.

"With T4 treatment of these animals with myocardial infarctions, they are more resistant to developing arrhythmias," Zhang said.

Zhang's study builds upon previous studies conducted at NYIT that demonstrate links between thyroid hormones and heart health in animal models. Five months ago, Zhang's collaborator A. Martin Gerdes, Ph.D., published a study in Molecular Medicine that found administering low doses of the active form of the thyroid hormone known as T3 prevented the development of heart disease in rats with diabetes. Previously, Gerdes has published studies demonstrating that hypertension and heart attacks also trigger low cardiac thyroid hormone levels and contribute to heart disease.

Gerdes and Zhang believe that human clinical trials involving patients with heart failure may lead to findings that radically change protocols.

The current study notes reluctance to use thyroid hormone replacement therapy in humans with heart diseases likely has its roots in several studies that used excessive doses of or thyroid mimics.

Explore further: Restoring thyroid hormones in heart may prevent heart disease from diabetes

Related Stories

Restoring thyroid hormones in heart may prevent heart disease from diabetes

June 25, 2014
Administering low doses of a thyroid hormone to rats with diabetes helps restore hormone levels in their hearts and prevented deterioration of heart function and pathology, according to a new study by NYIT College of Osteopathic ...

Thyroid hormones reduce damage and improve heart function after myocardial infarction in rats

February 28, 2013
Thyroid hormone treatment administered to rats at the time of a heart attack (myocardial infarction) led to significant reduction in the loss of heart muscle cells and improvement in heart function, according to a study published ...

Benefits of thyroid screening unclear

October 27, 2014
Researchers for the U.S. Preventive Services Task Force (USPSTF) suggest that more research is needed to determine the benefits of screening asymptomatic individuals for thyroid dysfunction. Their review is being published ...

Thyroid problems linked to irregular heart rhythm

November 28, 2012
People with an overactive thyroid gland (hyperthyroidism) carry a greater risk of developing irregular heart rhythm (known as atrial fibrillation) than those with normal thyroid function, finds a study published on BMJ today.

New hypothyroidism treatment guidelines from American Thyroid Association

September 30, 2014
Levothyroxine (L-T4), long the standard of care for treating hypothyroidism, is effective in most patients, but some individuals do not regain optimal health on L-T4 monotherapy. New knowledge about thyroid physiology may ...

Common diabetes drug associated with risk of low levels of thyroid hormone

September 22, 2014
Metformin, a commonly used drug for treating type 2 diabetes, is linked to an increased risk of low thyroid-stimulating hormone (TSH) levels in patients with underactive thyroids (hypothyroidism), according to a study in ...

Recommended for you

Eating yogurt may reduce cardiovascular disease risk

February 15, 2018
A new study in the American Journal of Hypertension, published by Oxford University Press, suggests that higher yogurt intake is associated with lower cardiovascular disease risk among hypertensive men and women.

Newly discovered gene may protect against heart disease

February 14, 2018
Scientists have identified a gene that may play a protective role in preventing heart disease. Their research revealed that the gene, called MeXis, acts within key cells inside clogged arteries to help remove excess cholesterol ...

Blood thinners may raise stroke risk in over-65s with kidney disease

February 14, 2018
People over 65 years old may be increasing their stroke risk by taking anticoagulants for an irregular heartbeat if they also have chronic kidney disease, finds a new study led by UCL, St George's, University of London and ...

Cardiac macrophages found to contribute to a currently untreatable type of heart failure

February 14, 2018
A team of Massachusetts General Hospital (MGH) investigators has discovered, for the first time, that the immune cells called macrophages contribute to a type of heart failure for which there currently is no effective treatment. ...

Study maps molecular mechanisms crucial for new approach to heart disease therapy

February 13, 2018
Creating new healthy heart muscle cells within a patient's own ailing heart. This is how scientists hope to reverse heart disease one day. Today, a new study led by UNC-Chapel Hill researchers reveals key molecular details ...

Quality toolkit improves care in Indian hospitals

February 13, 2018
A simple toolkit of checklists, education materials and quality and performance reporting improved the quality of care but not outcomes in hospitals in the south Indian state of Kerala and may have the potential to improve ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.