AUG 13, 2018 9:40 AM PDT

'Tic'-tock, slowing the clock for fast heart beat patients

WRITTEN BY: Caitlin Williams

Atrial fibrillation, also known as AFib or AF, is a rapid or irregular heartbeat (arrhythmia) that can lead to blood clots, stroke, and heart failure among other heart-related complications. Over 2.7 million Americans live with atrial fibrillation, describing the experience as “heart flip-flops or skipped beats” or for some no symptoms at all. Of those with atrial fibrillation, about 15-20% have strokes and double the risk for heart-related deaths. A recent study published in Circulation: Genomic and Precision Medicine, from researchers at Hiroshima University looked for markers to identify which people with atrial fibrillation were at high risk for developing heart failure.

An average heart rate is 60 to 100 beats a minute, in patients with atrial fibrillation, it can range from 100 to 175. During atrial fibrillation, the upper chambers of the heart, the atria, beat irregularly instead of normally to move blood to the ventricles. The irregular beat can lead to complications such as blood clots, stroke, and heart failure. Symptoms include weakness, fatigue, palpitations, dizziness, confusion, and shortness of breath among other things. Your age, blood pressure, alcohol consumption, weight, and family history can all increase your risk for atrial fibrillation. Eating a healthy diet, increasing physical activity, avoiding smoking and excessive caffeine and alcohol intake, as well as reducing stress can help prevent atrial fibrillation.

Atrial fibrillation can lead to a potentially fatal disease known as tachycardia-induced cardiomyopathy, if reversed damage can be prevented by bringing the proper rhythm of the heart back by drugs or catheter therapy. Little is known about the risk factors for tachycardia-induced cardiomyopathy and diagnosis occurs only when other potential heart disorders are ruled out. The research group from Japan, led by Dr. Yukiko Nakano, has sought to solve this problem by identifying genetic markers associated with tachycardia-induced cardiomyopathy.

Previous studies identified genetic variants associated with atrial fibrillation, two of which are cardiac ion channels that help regulate the heart’s conduction. The current study found one gene, HCN4, that indicates when a person with a fast heartbeat is more likely to develop tachycardia-induced cardiomyopathy and later heart failure. Gene HCN4 is known to have a critical function in the autonomic control of the heart. Nakano and her team studied 73 patients and found that small changes in the gene could indicate a higher risk of developing heart failure. The study shows that polymorphisms in HCN4 could be a genetic marker for tachycardia-induced cardiomyopathy, further studies will look at a larger cohort to confirm this.

"We will be able to distinguish the high-risk atrial fibrillation patients developing heart failure and consider [them] for early therapeutic intervention," Nakano said. "We can prevent their heart failure by stricter heart rate control or early rhythm control [using currently available heart devices and drugs]." It is also possible to utilize the genetic marker as a therapeutic target for drug development; this drug could help patients with atrial fibrillation maintain or restore normal heart rhythm.

To learn more about atrial fibrillation watch the video below!

Mayo Clinic, American Heart Association

About the Author
Doctorate (PhD)
Caitlin holds a doctorate degree in Microbiology from the University of Georgia where she studied Mycoplasma pneumoniae and its glycan receptors. She received her Bachelor's in Biology from Virginia Tech (GO HOKIES!). She has a passion for science communication and STEM education with a goal to improve science literacy. She enjoys topics related to human health, with a particular soft spot for pathogens.
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