MicroRNA Could Predict the Risk Of Atrial Fibrillation

A microRNA biomarker has been identified that shows a strong connection with the occurrence of artial fibrillation, the most frequent abnormal heart rhythm.

The team of researchers from the Intermountain Medical Center Heart Institute in Salt Lake City has been looking for microRNA biomarkers for guiding the diagnosis and possible treatment of difficult heart conditions as well as atrial fibrillation and heart failure.

For the study, the researchers wanted biomarkers that might particularly predict the occurrence and severity of atrial fibrillation, said the study’s lead author, Oxana Galenko, PhD, clinical research senior scientist in cardiovascular research at Intermountain Medical Center Heart Institute.

“We sought to produce particular profiles of the molecules and look if they could be used to differentiate between the risk of atrial fibrillation in various groups of patients,” Galenko mentioned.

The research team recognized microRNAs, stable, small, noncoding RNA molecules that negatively manage gene expression at a stage called the post-transcriptional level. These markers might potentially denote which atrial fibrillation patients are most possibly to benefit from ablation — a process that makes tissue scarring around the pulmonary veins and stops electrical impulses from being misdirected, which can result in atrial fibrillation.

Atrial fibrillation is characterize by a rapid and irregular heartbeat caused when the top chambers of the heart quiver erratically, sometimes faster than 200 times per minute. The condition can have a significant negative impact on an individual’s quality of life, cause heart palpitations, chronic fatigue, debilitating pain and can increase the risk of stroke fivefold.

In atrial fibrillation condition, the heartbeat is irregular and rapid and caused while the top chambers of the heart quiver unsteadily, faster than 200 times per minute. Atrial fibrillation can have a negative effect on a person's quality of life, chronic fatigue, making heart palpitations, debilitating pain and can maximize the risk of stroke by five times.

Atrial fibrillation and microRNA

“From the research, we learnt some markers that were cited generally for heart failure patients, so we identified which microRNAs we were going to observe, since we’ve observed them before,” explained Victoria Jacobs, NP, PhD, a member of the research team.

There are four subtypes in Atrial fibrillation, in which two are most frequent: Paroxysmal AF is periodic, where as persistent AF lasts and has various degrees of severity. The researchers expected to find out particular microRNAs involved in atrial fibrillation, in order to use them to differentiate between the two subtypes.

The Intermountain Medical Center Heart Institute keeps an extensive bio bank that has enarmouse amount of biological and medical data that’s gathered by obtaining a small amount of blood from consenting patients, then maintaining those samples for further research.

For the study, researchers made use of very small amounts of plasma from the bio bank. As microRNAs are so small and stable, they can be identified in circulating biological fluids such as saliva and blood.

The researchers tested samples from 140 atrial fibrillation patients among them 93 are paroxysmal and 47 are persistent and 50 people who never reported heart disease and served as a control group.

Researchers then tested many miRs that had been connected with atrial fibrillation, such as 21, 291, 133a, 133b, 150 and 328. They identified specific miR 21.

Researchers observed particularly at the levels of microRNAs in circulating blood of the patients and discovered that risk of atrial fibrillation is higher as levels of miR 21 decreased. When there are lower levels of the microRNA, it is highly connected with the development of atrial fibrillation, it wasn’t connected with any variations between paroxysmal and persistent AF.

The researchers consider that means the process of how the disease occurs and its development are different. In future studies, they hope to find out what initiates the disease.

“As atrial fibrillation progresses, we know there’s more fibrosis in the left atrium,” said Dr. Jacobs. “We have theories of what results in harmful fibrosis, along with which pathways are triggered to causes fibrosis. However we actually don’t know the reason yet. It’s uncertain if the microRNA transmits the signals then it develops to fibrosis or vice versa.”