Oct 6, 2011 3:20 PM
If you've been diagnosed with atrial fibrillation (AFib) -- a heart rhythm disorder in which the two upper chambers, known as the atria, quiver instead of beating at a steady pace -- your doctor will have two main goals for treatment.
You may be surprised to learn that resetting your heart's rhythm is the second goal of AFib treatment. People with atrial fibrillation are five times more likely to have a stroke than those who don't, so your doctor's first concern will be reducing your risk of stroke. "The biggest health risk from the AFib itself is that clots will form in the heart and cause a stroke," says William Whang, MD, assistant professor of clinical medicine in the division of cardiology at Columbia University Medical Center.
Once the stroke risk is under control, you can treat the actual atrial fibrillation.
Doctors assess the risk of stroke in people with atrial fibrillation using a formula called CHADS2. It stands for:
C-Congestive Heart Failure
H-High Blood Pressure
A-Age 75 or older
Each of the conditions earns you one point; a previous stroke gets you two. Recently, doctors have added a second half to the scoring system, which evidence shows is even more accurate. This formula, known as VASc, adds points for being a woman (women with AFib are at greater stroke risk), peripheral vascular disease, and being older than 65.
"The general recommendation is that all but the lowest-risk AFib patients take a blood thinner, such as Coumadin," explains John Wylie, MD, director of electrophysiology services for Massachusetts-based Caritas Christi Health Care. "Patients who score only a point on CHADS2-VASc should be fine taking daily aspirin to manage their stroke risk, but if your score is higher than one point, I will recommend Coumadin. I've seen too many strokes."
Blood thinners come with their own risks, such as gastrointestinal bleeding, joint problems, and uncontrolled hemorrhage. If your doctor puts you on a blood thinner, you also should be carefully monitored with regular blood tests.
In 2010, the FDA approved a new drug, dabigatran (Pradaxa) specifically to prevent stroke in people with AFib. Although this drug also carries with it a risk of bleeding, doctors say that it doesn't require the same monthly blood tests that Coumadin does. "It's more convenient and it may be slightly more effective," says Wylie. "On the other hand, it's also more expensive and not all insurance plans may cover it, and it's more difficult to reverse quickly if someone is in a traumatic accident that causes bleeding."
Once stroke risk is under control in a patient with AFib, doctors turn their attention to the actual heart rhythm problem. Not everyone needs their AFib corrected. Some people with atrial fibrillation can go years without any treatment other than stroke prevention.
"A lot of people have so-called chronic AFib, where it's there all the time, but as long as their heart rate isn't too fast, they're able to live their lives normally, and in some cases don't even notice it," says Whang.
So if you don't have symptoms from your AFib and your heart function is normal, your doctor may not try to get your heart back into a normal rhythm. "There's no evidence showing that doing this will make a person live longer or have a lower stroke risk," Wylie says. "So it's hard to make the case for prescribing drugs and surgical interventions, which have their own risks.
If you do have symptoms, that's a different story. Symptoms of atrial fibrillation include:
One of the first options to control atrial fibrillation that won't stop on its own is a procedure called cardioversion. The patient is placed under general anesthesia and doctors deliver an electrical shock to reset the heart's rhythm back to normal.
"This isn't a permanent fix," says Whang. "Sometimes a person could have a recurrence of their AFib by the time they get home from the procedure. But getting the person back into normal rhythm, even for a short time, can tell us whether or not that makes them feel better. That tells us what we should do about treatment."
That's particularly helpful in a young person who may not think that their AFib is causing them symptoms but notices a dramatic difference after cardioversion. "They'll say, 'Wow, I didn't realize I was feeling so bad! I thought I was just getting lazy, but it was really the AFib that was sapping my energy,'" Wylie says.
Prior to performing cardioversion, doctors must make sure that there are no clots lurking in the atria that could be dislodged by the procedure and cause a stroke. Usually a month on blood-thinning medications will dissolve any hidden clots. If symptoms are too severe to wait that long, cardiologists will perform a procedure called a transesophageal echocardiogram (TEE).
Traditional echocardiograms use ultrasound transducers placed on the outside of the chest. A TEE gives a more detailed picture of the heart's left atrium, where clots associated with AFib usually hide. Doctors guide the ultrasound transducer, attached to a long flexible tube called an endoscope, directly down the patient's esophagus, which runs right behind the left atrium. This outpatient procedure is usually performed under IV sedation.
The next step in restoring the heart's normal rhythm is medication. There are several medications used to treat atrial fibrillation. For a patient whose AFib is more or less constant, doctors will usually combine medications with cardioversion. For someone who is in and out of atrial fibrillation, they usually use medication alone.
There are two main categories of drugs used in people with atrial fibrillation: rate control drugs and anti-arrhythmic drugs.
Rate control drugs control your heart rate. In a lot of people with atrial fibrillation, the problem isn't so much the off-kilter rhythm; it's that it's simply beating too fast. "When the heart rate is over 100 beats per minute for very long, over time the ventricles, the bottom pumping chambers, can become weak," says Whang. "So it's important to try to control the heart rate.
To do that, doctors usually prescribe beta-blockers or calcium channel blockers, medications that are commonly used to treat high blood pressure and heart disease. They also work to keep the heart rate from going into overdrive -- and they are very well understood and have limited side effects.
To correct the arrhythmia itself, there are no 'magic pills.' "In general, most of the anti-arrhythmic medications we have today are effective between 45% and 55% of the time," says Wylie. Some are more effective than others, and they all come with their own side effects. The most effective, amiodarone, also carries the heaviest side-effect burden, including potential thyroid, lung, and liver damage. "It requires frequent monitoring, just to be sure the person is tolerating it," says Whang.
If you've tried multiple anti-arrhythmic drugs but still can't seem to get control of your AFib symptoms, doctors may recommend catheter ablation. This is a surgical procedure, although it's minimally invasive.
In catheter ablation, doctors make small incisions in the groin and thread long, thin tubes called catheters through a vein up to your heart. The catheters can deliver either radiofrequency (heating) or cryoablation (freezing energy) to treat areas in the atrium that are triggering and sustaining the atrial fibrillation. Basically, it creates scar tissue in certain areas of the heart that cause the AFib, disconnecting them electrically from the rest of the heart.
How well does it work? For patients who are in persistent atrial fibrillation and have had multiple cardioversions, Wylie says, the success rate is about 50%-60%. For "paroxysmal" patients -- those in and out of AFib -- success is higher, about 70%-75%.
"There are dramatic cases of people in AFib who have had their quality of life ruined by symptoms, and afterward, their frequency of AFib goes down to essentially zero," says Whang. 'We don't yet know, though, if ablation for AFib improves actual stroke risk and survival, as opposed to just quality of life."
And those success figures are based on 1.5 procedures per patient, Wylie adds. "That means that there's a 50-50 chance you'll need a second procedure to get results."
Catheter ablation has its own risks, as well. Overall, about 5% of patients experience some type of complication, including bleeding where the catheter enters the groin or when it perforates the heart, as well as a 1% risk of stroke. And in very rare cases -- fewer than one in 1,000 -- an esophageal fistula can develop, which is an opening between the heart's left atrium and the esophagus. "That's a life-threatening complication and is fatal about half of the time," says Wylie.
In some cases, such as if a person is already undergoing heart surgery, doctors may skip the catheter approach and choose to do the ablation during the surgery itself.
Whatever the treatment, the main reason to treat atrial fibrillation itself is to improve your quality of life. "Although that might change in the near future, we cannot now offer patients, for instance, the ability to go off blood-thinning medications if their AFib is stabilized. There might still be a need for those even if they are no longer in AFib," says Whang.