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Untreated AFib is associated with a 45% increased risk of developing mild cognitive impairment, a new research letter says. spxChrome/Getty Images
  • For people with untreated atrial fibrillation (AFib), the risk of developing mild cognitive impairment, and perhaps dementia, appears to be significantly higher, according to a new research letter.
  • The study found that people whose AFib is being successfully treated are at no higher risk of cognitive issues.
  • AFib can result in tiny, imperceptible blood clots, degrading the brain’s function over time.
  • For people with comorbidities along with untreated AFib, the risk of mild cognitive impairment and dementia is even greater.

A large study found that there is an association between untreated atrial fibrillation (AFib) and eventual mild cognitive impairment (MCI) that may lead to dementia.

Researchers found that people with AFib were at a 45% higher risk of MCI than those without AFib or with AFib that was being treated.

The researchers found that people being treated with two drugs, digoxin or amiodarone, along with oral anticoagulants — blood thinners — were not at a higher risk of MCI than controls.

The study is published as a research letter in JACC: Advances.

The study analyzed electronic health records from January 1, 1998, to May 31, 2016, for 4,309,245 individuals residing in the United Kingdom.

Each of the 233,833 people with AFib was matched with one of 233,747 people of the same sex and age, but without AFib to serve as a control. The mean age of individuals was 74.2.

The researchers adjusted for a wide range of potential MCI risk factors, including:

“The thought has been that if someone has atrial fibrillation — especially under-treated atrial fibrillation — they’re having multiple little embolic strokes,” cardiologist Dr. Paul Drury, associate medical director of electrophysiology at MemorialCare Saddleback Medical Center in California, who was not involved in the study, explained to Medical News Today.

Dr. Jayne Morgan, a cardiologist and clinical director of the Covid Task Force at the Piedmont Healthcare Corporation in Atlanta, GA, also not involved in the study, told MNT, “Silent brain infarcts, like silent heart attacks, do damage to tissue and cells, regardless of symptomatology, or lack thereof. AFib, in particular, is recognized as a risk factor for silent brain insults in this population.”

“Over time, this takes its toll on cognitive function, accelerating mental decline. This is because small blood clots, which are more common to develop with untreated AFib, can block small arteries feeding oxygen to the brain, depriving the brain of oxygen and then [causing] the subsequent death of that tissue.”

— Dr. Jayne Morgan, cardiologist

“Those strokes eventually will affect the volume of brain tissue and healthy brain tissue and then lead to cognitive impairment, and then dementia,” Dr. Drury added.

In addition to the association with AFib, the researchers found certain individuals were at a higher risk for MCI, including:

  • older people
  • females
  • people with greater socioeconomic deprivation
  • individuals with a clinical history of depression
  • people who’ve had a stroke

The researchers also found that people with AFib who developed MCI were at a higher risk of developing dementia.

The risk factors most likely to result in dementia were:

In the research letter, Dr. Morgan said “It was astonishing to see that all 20 co-morbidity variables were not only often higher in the AFib group, but those that were higher were often more than twice as high as the controls.”

She also pointed out one especially striking, often overlooked co-morbidity — hearing loss, which has been linked to an increase in cognitive decline.

Atrial fibrillation is a form of arrhythmia characterized by an irregular or quivering heartbeat. It can lead to several cardiovascular complications, including:

AFib currently affects more than 2 million U.S. adults, and the American Heart Association (AHA) predicts that 12 million people will have AFib by 2030 as the national population ages.

AFib is caused by an irregular beating in the atria, which is the upper chambers of the heart.

When this irregular beating occurs, some blood that should be pumped out from the heart remains. This pooled blood can form clots in the heart that may eventually be pumped out to the brain, causing a stroke.

The medications mentioned in the study, digoxin and amiodarone, were in use more widely during the earlier years of the study than they are today.

Dr. Drury said digoxin “is not actually recommended for treatment of atrial fibrillation anymore — it is one that only controls the heart rate.”

While amiodarone, an antiarrhythmic medication, is still in use, Dr. Drury said it is not as frequently prescribed now due to “a lot of side effects.”

Instead, he said, “there is cardiac ablation, which is now one of our first-line therapies that didn’t start really until the early 2000s.” He noted that there are other antiarrhythmics, but they are not as commonly used as amiodarone once was.

Dr. Drury explained cardiac ablation:

“We go minimally invasively from the veins in the legs all the way up to the heart, and we ablate, or cauterize, the tissue in the heart that causes atrial fibrillation. So instead of putting a band-aid on it with medication, we’re actually fixing the problem.”

Since cardiac ablation is only about 70–80% effective, it is frequently supplemented with anticoagulants.

“Treatment of AFib is not just a cardiac consideration, but a cognitive one as well. [The] takeaway is that it is critically important to manage all co-morbidities to goal in AFib patients, as not doing so could both hasten and increase the risk of mental disability in these patients as they age.”

— Dr. Jayne Morgan