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Anti-Arrhythmic Drugs continued...

Most of the common anti-arrhythmic drugs have similar success rates: anywhere between 45% and 55%, says Wylie.

Then there’s amiodarone ( Cordarone, Pacerone), which is a bit of a hybrid. It’s both a sodium channel blocker and a potassium channel blocker. It’s by far the most effective anti-arrhythmic drug available -- possibly as much as 75%, Wylie says. But because it lingers in many parts of the body for a long time, it has many possible side effects, including lung, liver, and thyroid damage.

“Because of this, we usually will not prescribe it in people who are younger and likely to be treated for a long period of time,” says Whang. If you’re on amiodarone, you’ll have to have regular liver, lung, and thyroid function tests.

There’s also a somewhat controversial new drug called dronedarone (Multaq). “It was designed to be like amiodarone without the side effects, but it turned out to be amiodarone with some of the side effects and none of the efficacy,” says Wylie. “The trials showed that it didn’t keep people in sinus rhythm very well.”

The drug’s manufacturers say that it did keep people with atrial fibrillation out of the hospital more effectively, however. “It may not prevent AFib, but it might prevent some of the symptoms of AFib, perhaps by blunting fast heart rates,” Wylie concedes. “I rarely use it, but some people love it because it does make some people feel better, and after all, we’re treating for symptoms.”

But in January 2011, the FDA reported two cases of acute liver failure, requiring a transplant, tied to dronedarone. “That didn’t show up in the trials, but if we start seeing more of this, then you’ve got a drug that doesn’t work all that well and is toxic,” Wylie says.

In July 2011, the FDA warned that a clinical trial of dronedarone was halted when the drug doubled the risk of death, stroke, and heart failure hospitalization in heart patients with permanent atrial fibrillation.

In 2013, the FDA reported more adverse effects of the drug on lung function. The drug can cause shortness of breath or cough related to lung damage. Call your doctor if you develop shortness of breath or a dry cough during treatment.

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