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Peter Noseworthy, M.D.
Peter Noseworthy, M.D.

More than 33 million people worldwide experience atrial fibrillation (AF or a-fib) – a fast and irregular heartbeat. This condition can go almost unnoticed, or be debilitating, causing shortness of breath and fatigue. A-fib itself is typically not life-threatening, but it does bring a higher risk of stroke – from one in 200 to as high as one in every 10 a-fib patients.

Fix the a-fib, and you’re no longer at risk, right?

Peter Noseworthy, M.D., says, “Absolutely not.”

To lessen the risk of stroke for a-fib patients, and those with other conditions that can cause strokes, doctors prescribe anticoagulants (medications that thin the blood and reduce clotting ability).

A cardiac electrophysiologist at Mayo Clinic, Dr. Noseworthy specializes in diagnosing and treating dysfunctional hearts. He and fellow physicians were concerned that patients might be stopping use of anticoagulants after they had cardiac ablation to fix the atrial fibrillation, but while they still were at risk for stroke.

So Dr. Noseworthy and a team of researchers decided to investigate. Their findings were published recently in the Journal of the American Heart Association. Using the OptumLabs™ Data Warehouse, the researchers looked at the health care claims information for nearly 7,000 patients who had cardiac ablation for a-fib.

Patients who stopped taking anticoagulant medication within three months after cardiac ablation were at an immediate (within 24 hours) risk of stroke. The risk is actually higher in the first months following the ablation, as the procedure itself can cause clots. The team believes that if the only condition patients have that causes elevated stroke risk is a-fib, staying on anticoagulants for three more months is the safest course.

However, they also observed that many patients had other risk factors for stroke that warranted anticoagulation use. For those patients, discontinuing anticoagulants would never be appropriate. Yet the researchers saw discontinuation after cardiac ablation – and, unsurprisingly – more strokes.

Dr. Noseworthy thinks he understands why. “If we normalize heart rhythm, the perception is that the risk goes away. However, this is not the case.

“As we show, stopping the blood thinner shortly after ablation increases risk of stroke, and,” he cautions, “A patient’s other risk factors don’t go away when they no longer have atrial fibrillation.”

The researchers call for more education among health care providers and patients, and hope that their findings will save lives.

Dr. Noseworthy is a Kern Health Care Delivery Scholar in the Mayo Clinic Robert D. and Patricia E. Kern Center for the Science of Health Care Delivery. Center work focuses on improving health and the delivery of health care. OptumLabs was co-founded by Mayo Clinic and Optum in 2012 as a research collaborative able to mine big data to find solutions to problems in today’s health care system.