Not all patients who have a heart ablation procedure need to be on the powerful blood thinner warfarin afterwards to prevent blood clots and stroke, according to research from Intermountain Medical Center.

For many, aspirin works just as well, with less risk.

The same researchers also found that changing the way ablations are done can reduce the amount of collateral damage to surrounding tissue.

Both findings are being presented this week at the Heart Rhythm Society of America's annual scientific sessions in San Francisco.

In ablation procedures, heart tissue is "zapped" to short-circuit errant electrical activity that contributes to atrial fibrillation, a dangerous rhythm disorder.

Warfarin (brand name Coumadin) is a powerful blood thinner that's routinely prescribed to patients for at least two months after a heart ablation, according to Dr. John D. Day, cardiologist and medical director of IMC's Heart Rhythm Services. They studied 540 patients in 692 ablation procedures and found that patients at lower risk of a stroke did just as well on an aspirin a day, right from the beginning.

They didn't test it in patients at high risk of stroke, including those with a previous history, with diabetes, high blood pressure, older than 75 or in heart failure, he said.

"It's good news, because warfarin has a 1 percent chance each year you're on it of a life-threatening bleed — either a hemorrhagic stroke or elsewhere in the body," Day said.

The IMC researchers also found that changing the way catheter ablation is done reduces risk of collateral tissue damage.

Generally, ablation is accomplished by zapping tissue one spot at a time using low-dose energy for about 20-45 seconds, then moving on to the next spot, But researchers found that using higher power and keeping the catheter moving avoids creating gaps, and lessens the chance of damage to surrounding tissue such as in the lungs, esophagus or nerves on the outside of the heart.

The difference amounts to drawing, rather than dabbing. And it's considerably faster, as well, said Day of the outpatient procedure.

The study involved 1,027 ablation procedures.

The specialist doing the catheter ablation may go over tissue again after it's cooled, but the goal is to keep moving, Day said, who called the new technique a "complete paradigm shift."

Cardiologists have been coming to IMC from around the world to learn the new technique, he said.

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