I collapsed during my 10k run then got diagnosed with atrial fibrillation

“I’ve always considered myself very fit and healthy going through life. I’ve always exercised, I’ve never been overweight, I eat good food, I’ve never smoked, I drink very moderately, and there’s no family history of heart issues. So I had no reason to suspect that I was going to have any heart problems,” he explains.

Mike Munson, a keen runner, was nearly 50 when he lined up for a 10k run. “It was a fairly flat course, but after a few hundred yards, I felt completely drained – I had no energy. I didn’t know what was happening, but I knew I had to stop. I wanted to keep going, so I did, but I kept stopping, restarting, walking, and jogging around the 10k course. I collapsed at the finish, exhausted. I then went to the hospital to get tested. I had the usual tests, but nothing was really done at this stage,” he says.

This went on for about six years. Mike kept trying to run only to get dizzy and blackout. Eventually, he was diagnosed with atrial fibrillation (AF).

What is atrial fibrillation?

AF is the most common abnormal heart rhythm. Around 1.5 million people have been diagnosed with AF in the UK. AF happens when electrical impulses fire off in the upper chambers of the heart (the atria) in a disorganised way. These chaotic impulses cause the atria to quiver or twitch, which is known as fibrillation. People with AF have an irregular, and sometimes fast, heartbeat or pulse. They can have uncomfortable or debilitating symptoms, or no symptoms at all.

Discovering whether “silent” atrial fibrillation can damage the brain

Short episodes of AF are relatively common, particularly in older people, and can go unnoticed, so many people will never get diagnosed. But we don’t know to which extent “silent” AF episodes, especially when of short duration, can cause damage to the brain, leading to a subsequent decline in brain function.

To find this out, we are currently funding BHF Professor Barbara Casadei and colleagues at the University of Oxford to follow 30,000 people registered in UK Biobank. They will monitor the heart rhythm of participants using a skin patch recorder and will use MRI scans to detect damage to blood vessels in the brain, alongside tests that measure people’s brain function.

If this research shows that silent AF increases the risk of stroke and dementia, then close monitoring and treatment of AF may avoid many occurrences of stroke and slow down or prevent the development of dementia. This would be a major step forward.

“Our long-term aim is to understand the relationship between the causes of AF and cognitive function, as well as the impact of silent AF on the future risk of stroke and dementia,” Professor Casadei explains.

“We also want to know what the impact of the burden of AF is. At the moment, whether you have 30 seconds or 24 hours of AF, the requirement for blood thinners to prevent stroke is the same - we really want to understand what the difference is.”

Do you want to hear more from Professor Barbara Casadei and Mike Munson about atrial fibrillation?

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