People with failing kidneys are at increased risk of developing a life-threatening abnormal heart rhythm, a new report suggests.
Chronic kidney disease can as much as double a patient’s risk of atrial fibrillation, a quivering or irregular heartbeat that can lead to stroke or heart failure, said lead researcher Dr. Nisha Bansal. She is an associate professor of nephrology at the University of Washington’s Kidney Research Institute, in Seattle.
The risk of atrial fibrillation increases as kidney function declines, Bansal said.
“We saw the worse your kidney function, the greater your risk of developing atrial fibrillation. Even mild changes in kidney function were strongly linked to atrial fibrillation,” Bansal noted.
The study included data gathered from three separate research projects focused on heart health in the United States. The three projects created a combined pool of almost 17,000 patients with follow-up periods averaging between 8.5 years and 12.5 years. None of the participants had atrial fibrillation when first recruited.
Each project checked participants’ kidney function when they first joined the study, using one or two different lab tests. One was a blood test that evaluated how well the kidneys were removing toxins from the bloodstream. The other was a urine test that assessed whether the kidneys were properly filtering out a specific protein.
People with worse kidney function at the start of the study were more likely to have atrial fibrillation by the end, the researchers found. Those who did worse on the blood test were twice as likely to develop an abnormal heart rhythm, while those who did worse on the urine test were 76 percent more likely.
While the association doesn’t prove a cause-and-effect relationship, the link remained even after the researchers took into account other risk factors for atrial fibrillation, such as diabetes, tobacco use and a history of heart problems.
“We found that kidney function was independent of all other risk factors,” Bansal said.
Research has not yet been conducted to explain the association between kidney function and atrial fibrillation, Bansal noted, but there are a number of possible explanations.
A poorly functioning kidney can alter blood levels of a number of nutrients needed to maintain proper heart function, such as potassium, vitamin D, calcium and phosphorus, Bansal said.
The kidneys also are responsible for maintaining a steady volume of blood in your body, removing excess fluid by way of urination.
“If your kidney function is impaired, your blood volume increases,” Bansal said. “That increased stress on your heart causes it to stretch and can also trigger this abnormal heart rhythm.”
Dr. Kevin Chan, a nephrologist with Massachusetts General Hospital in Boston, noted that it’s also possible toxins that haven’t been filtered from the blood — thanks to a bad kidney — might have some as-yet-unknown effect on heart function.
Based on this report, doctors treating patients with kidney disease should keep an eye out for potential heart problems, said Chan, who was not involved with the new study.
“Physicians should be cognizant of this relationship so they are attuned to recognizing atrial fibrillation when they see their chronic kidney disease patients,” Chan said.
Doctors can reduce a person’s risk of stroke from atrial fibrillation by putting them on blood thinners, he added. Atrial fibrillation patients also can be fitted with a pacemaker, or undergo a procedure to restore proper heart rhythm.
People with kidney disease could help themselves by adopting a heart-healthy lifestyle, Bansal suggested, for example, eating right, exercising and quitting smoking.
“A heart-healthy lifestyle does improve your risk of all kinds of cardiovascular disease, as well as kidney disease, so I would recommend that,” Bansal advised.
The report was published online Aug. 10 in the Clinical Journal of the American Society of Nephrology.