"If your heart rhythm is off but the rate isn't too fast, that isn't as much of a problem," says William Whang, MD, assistant professor of clinical medicine in cardiology at Columbia University Medical Center.
"But when the heart rate is over 100 beats per minute for very long, the bottom pumping chamber -- the ventricle -- can become weak," he says. This leads to a condition called cardiomyopathy, which puts you at greater risk for heart failure.
The two types of medication most commonly used to slow a racing heart are:
- Calcium channel blockers
If you aren't bothered by symptoms, your doctor may decide that correcting your heart's rhythm may not be worth the side effects.
But some people with AFib do struggle daily with fatigue, shortness of breath, and dizziness. If you do, your doctor may recommend an anti-arrhythmic medication to steady your heartbeat and help ease those symptoms.
Some drugs slow down how fast electrical signals can travel in the heart muscle. These sodium channel blockers include flecainide (Tambocor) and propafenone (Rythmol). But people with coronary disease or any kind of heart failure can't use them, cautions John Wylie, MD, director of electrophysiology services for Massachusetts-based Caritas Christi Health Care.
Other drugs slow nerve impulses in the heart. Potassium channel blockers include dofetilide (Tikosyn) and sotalol AF (Betapace AF). They affect the kidneys, Wylie explains, which means you can't take them if you have kidney problems.
And while it may help fix the rhythm in the top part of your heart, dofetilide might also cause life-threatening abnormal heartbeats in the bottom part of your heart, too. You'll start taking it in the hospital. That way, doctors and nurses can watch you carefully during the first few days, when most of these complications happen.
Most of the common anti-arrhythmic drugs work between 45% and 55% of the time, Wylie says.
Then there's amiodarone (Cordarone, Pacerone), which is 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 can have many side effects. Doctors won't usually prescribe it if you're young and likely to be treated for a long time, Whang says.
A somewhat controversial newer drug called dronedarone (Multaq) "was designed to be like amiodarone without the side effects," Wylie says. It does have fewer side effects, but "the trials showed that it didn't keep people in sinus rhythm very well."
The drug's manufacturers say that it kept people with atrial fibrillation out of the hospital, and Wylie agrees that may be true. "It may not prevent AFib, but it might prevent some of the symptoms of AFib, perhaps by blunting fast heart rates."
"I rarely use it," he says, "but some people love it because it does make some people feel better, and after all, we're treating for symptoms."
In January 2011, the FDA reported that two people needed a transplant because of liver failure 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.
And in 2013, the FDA reported it can cause shortness of breath or a cough related to lung damage.
Be mindful of these possible side effects, and call your doctor if you notice any trouble while you're taking dronedarone.