Irregular Heartbeat May Have Wide-Ranging Effects in the Body

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The effects of an irregular heartbeat can ripple across the entire body, a new meta-analysis finds.

The particular type of irregular heartbeat that researchers looked at, called atrial fibrillation, is a well-known cause of strokes, but the condition also increases a person's risk for complications such as heart failure, kidney disease and dying of heart disease, according to the meta-analysis.

In the study, published Sept. 6 in the journal The BMJ, researchers analyzed 104 studies that included a total of more than 9 million patients, including more than half a million who had atrial fibrillation. In their analysis, the researchers determined how much having atrial fibrillation increased people's risk for problems such as stroke, heart failure and kidney disease. [Heart Disease: Types, Prevention & Treatment]

They found that people with atrial fibrillation had a 2.3 times greater risk of ischemic stroke, which is a type of stroke caused by a blood clot, than those who did not have the heart condition. A person's increase in risk of developing heart failure, however, was even greater: Atrial fibrillation increased the risk of heart failure by fivefold, the researchers found.

In addition, during the studies, people with atrial fibrillation were twice as likely to die of heart disease, 1.6 times as likely to develop kidney disease and 1.9 times as likely to have sudden cardiac arrest than those who did not have atrial fibrillation, according to the new study, led by Dr. Ayodele Odutayo, a graduate student at the Centre for Statistics in Medicine at the University of Oxford in England.

When an individual has atrial fibrillation, the two upper chambers of the person's heart (called the atria) beat irregularly. This can cause blood to pool in the heart, and blood clots can form in this pooled blood. These clots can travel up to the brain and block off a blood vessel, causing a stroke.

But it's unclear if there is a cause-and-effect link between atrial fibrillation and the other conditions, according to the meta-analysis. Instead, it's possible that atrial fibrillation doesn't directly cause problems such as heart failure or kidney disease, but rather that other culprits — such as high blood pressure — may be responsible for both conditions, the researchers wrote. In other words, in a person with atrial fibrillation and heart failure, the underlying cause of both may be high blood pressure.

Even though the meta-analysis doesn't point to atrial fibrillation causing nonstroke complications, the findings still suggest that doctors should consider the potential complications if a person has an irregular heartbeat, the researchers wrote in the paper. It would be beneficial to develop clinical models that could predict a person's risk for these complications if he or she has atrial fibrillation, they added. 

Originally published on Live Science.

Sara G. Miller
Staff Writer
Sara is a staff writer for Live Science, covering health. She grew up outside of Philadelphia and studied biology at Hamilton College in upstate New York. When she's not writing, she can be found at the library, checking out a big stack of books.