Features October 2014 Issue

Earlier Ablation, More Drug Options Highlight New Thinking on Afib

Greater awareness of atrial fibrillation and more aggressive treatment are helping combat this growing problem in the aging population.

You may have seen headlines earlier this year proclaiming the higher numbers of hospitalizations due to atrial fibrillation (Afib). While some of the reasons for this increase are due to a population that's living longer and a rise in Afib risk factors, the numbers also reflect greater patient awareness of the disease and more treatment options for physicians, according to cardiologist Walid Saliba, MD, medical director of the Center for Atrial Fibrillation at Cleveland Clinic.

Catheter ablation to treat atrial fibrillation is done by extending catheters through a vein to an area of the heart causing the chaotic electrical activity that triggers the arrhythmia. In many cases, the target is the point where the pulmonary vein meets the heart in the left atrium (above).

"It is a disease of the elderly," Dr. Saliba says. "So we are seeing more and more atrial fibrillation. But 15 years ago, our treatment options were limited. With the advent of newer technology and by being more aggressive about treatment, patients are aware that they have options."

Some of those options were among the highlights of new Afib treatment guidelines issued earlier this year by the American College of Cardiology and the American Heart Association. The guidelines covered topics such as the best candidates for an Afib treatment known as ablation, as well as what medications are appropriate for individuals dealing with the most common type of abnormal heart rhythm (arrhythmia).

Causes of Afib
While Afib is not exclusively an age-related disease, your risks of developing Afib do increase as you get older. But Afib can begin when you're in your 40s or 50s. And in mild cases, you may not even be aware that your heart is out of rhythm.

Among the factors most strongly associated with Afib are high blood pressure, coronary artery disease, heart valve disease, heart failure, pulmonary embolism, chronic lung disease and congenital heart disease. Afib can also develop after heart surgery.

Afib is characterized by an erratic and unpredictable beating of the heart's upper chambers, known as the atria. The condition is the result of chaotic activity within the heart's electrical system that normally keeps the heart's chambers pumping in a synchronized and efficient manner.

Treatment
Dr. Saliba says that there are three primary goals with Afib treatment. The first is to reduce the heart rate when Afib is present. Some people experience episodes of Afib that occur infrequently. For other individuals, Afib is a chronic condition. Medications such as beta blockers can often help reduce the heart rate.

The second treatment goal is to reduce the risk of stroke. When the atria quiver during Afib, blood doesn't move efficiently through and out of the heart. Blood can pool in the atria and clots can form. If one of those clots escapes the heart and reaches the brain, the result can be a stroke.

For many years, Afib patients were put on the anticoagulant warfarin to help lower the odds of clot formation. The new guidelines say that other, relatively new warfarin alternatives, could be considered. These include dabigatran, rivaroxaban and apixaban.

"These are for certain types of Afib patients," Dr. Saliba says. "You have to have atrial fibrillation not associated with valve disease."

He adds that those medications have some advantages over warfarin, though they are still more expensive than warfarin. Patients who take warfarin must undergo frequent monitoring to make sure it's working properly. If testing shows that blood is clotting too quickly, the warfarin dosage is increased. If clotting occurs too slowly, the dosage is reduced.

The new guidelines also downgraded the role of daily aspirin therapy for stroke reduction in patients with Afib. Dr. Saliba explains that there isn't evidence to support the idea that the potential benefit of aspirin outweighs the bleeding risks associated with aspirin.

But there are other promising stroke-prevention treatments out there. One is left atrial appendage (LAA) occlusion device. The LAA is a small pouch connected to the left atrium. It's also a place where blood clots tend to form in individuals with Afib. An LAA occlusion device closes off the pouch. Boston Scientific has an LAA occlusion device called the WATCHMAN , which is in use in Europe, but not the U.S.

"I'm encouraged about the prospect of it (Watchman )," Dr. Saliba says of the device, which he expects will receive approval by the U.S. Food and Drug Administration in 2015.

Ablation for Afib
The third treatment goal is to maintain a normal rhythm. In addition to antiarrhythmic medications, treatment for Afib includes catheter ablation. Catheter ablation is done by inserting a thin, flexible catheter in a vein (usually in the leg) and guiding it up to the heart. The tip of the catheter is fitted with a tiny electrode that sends out radio waves to heat up and destroy the portion of heart tissue that is the source of the erratic electrical activity.

Ablation is often successful, though it's not always possible to pinpoint the origin of the electrical problems. And if one Afib source is ablated, there's no guarantee that the arrhythmia won't reappear in another spot in the atria.

But because ablation is improving and becoming more effective, the doctors proposing the 2014 guidelines suggest it be considered as a first-line therapy for Afib. "The reason is the effectiveness of ablation," Dr. Saliba says.

Traditionally, ablation isn't attempted until after antiarrhythmic drugs prove to be ineffective at managing the condition. Dr. Saliba explains that some patients don't want to try medications. He notes that trying to control Afib with drugs means taking the antiarrhythmic medications every day for life.

A relatively new technology, called Focal Impulse and Rotor Modulation (FIRM), has shown promise as a more precise means of "mapping" the heart to better identify the sources of Afib.

Rotors are sometimes referred to as "electrical tornadoes" in reference to their strong, but chaotic influence on the electrical pathways in the heart. "They exist in the atrium and are responsible for the maintenance of atrial fibrillation," he says.

Dr. Saliba says Cleveland Clinic is getting a FIRM mapping system this year, and that he's interested in seeing firsthand whether this approach will be an improvement over the traditional ablation approach. A commonly done ablation therapy targets the area where the pulmonary vein attaches to the left atrium. This is sometimes called pulmonary vein isolation ablation.

Dr. Saliba says that ablation is an especially appealing option for younger Afib patients.
"We know it's a progressive disease," he says. "We know that in time, these medications will stop working. So going straight to ablation, which might change the course of the disease, could be of real value."

What you can do
If you have atrial fibrillation:

- Follow your anticoagulation medication regimen carefully, but report episodes of bleeding or other signs that your meds may need to be re-evaluated.
- Talk with your doctor about caffeine and alcohol, as they can be Afib triggers.
- Get regular exercise, as it helps control weight and blood pressure while also improving mood and your sleep. All these factors affect your quality of life with Afib. Just make sure to talk with your doctor about an exercise routine that is safe for you.

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