Heart racing or skipping? You might’ve developed ‘AFib’

What’s the common thread between daylight saving time, dementia and the late Fleetwood Mac singer Christie McVie? 

It's atrial fibrillation, the most common heart arrhythmia in adults. "AFib" is projected to affect 12 million U.S. residents by 2030. 

The condition, in which the heart’s upper chambers quiver like a hummingbird’s wings rather than squeeze, has recently been linked to dementia and other medical conditions. It reportedly contributed to McVie’s death last year. Cardiologists have noted higher inpatient admissions for AFib after daylight saving time changes.

And since it usually develops in people over 60, “AFib is expected to be increasingly prevalent going forward,” said Dr. Nazem Akoum, an electrophysiologist with the UW Medicine Heart Institute. He has cared for these patients since 2009.

AFib symptoms vary. Some patients, in their initial meeting with Akoum, say their heart is racing or feels like it is skipping. Others feel more tired, especially with exertion. A third group, typically people who are elderly or sedentary, don’t sense any change in their body or energy level.  Yet another group is, sadly, diagnosed with AFib after  they’ve suffered a stroke — the great potential peril of this irregular rhythm.

“Nobody wants to hear they have a new medical problem,” Akoum said. “People come in with a lot of anxiety about having a heart condition. First thing I tell them: This arrhythmia won’t make you keel over and die, but it also isn’t benign.”

Some AFib cases have a genetic component: If you have a parent or sibling with the condition, your chances of developing it are four to five times greater. But it typically results from the wear and tear of age that affects all bodily structures.

“If you lose healthy heart cells, the body replaces them with scar tissue, which in turn can interrupt the electrical signals that travel through the heart muscle to make it pump predictably. Then the signals have to try find another path to create that contraction, and can start going in circles,” Akoum explained.

When electrical signals are interrupted or detoured, the heart stops knowing what to do — and when it fails to pump routinely, blood can pool and clot inside it. 

The condition is a major cause of stroke because the brain receives about 20% of the output of every heartbeat, Akoum said, so the likelihood is high that a clot leaving the heart will travel to a branch vessel that feeds the brain and halt blood flow.

To address this possibility, blood thinners are a first-line treatment for most patients. Medications that control heart rate and heart rhythm also can be prescribed to help reduce patients’ arrhythmia symptoms.

“Getting patients to feel better means we have to overcome this disturbance in the rhythm,” Akoum said. “We try to get them out of atrial fibrillation,” he said.

Perhaps curiously, one effective strategy to stop chaotic electrical signals is to deaden additional heart cells. This process, ablation, is Akoum’s bailiwick. He maps the heart’s atria to locate the likely origin of the arrhythmia. Then, navigating a catheter into the heart, he zaps tissue in 3mm increments using either heat or freezing cold, thereby rendering it unable to trigger or conduct the errant signals and restoring a path to conduct a normal signal.

“It's not perfect but it's the most powerful tool we have, with about a 70% chance of suppressing somebody’s AFib completely,” he said.

-Written by Brian Donohue - 206-543-7856, bdonohue@uw.edu