DEAR DOCTOR K:

I went to my doctor after a few episodes of shortness of breath. It turned out to be atrial fibrillation. How is this condition treated?

DEAR READER:

Atrial fibrillation is a heart rhythm disorder that causes a rapid and irregular heartbeat. In this condition, electrical signals in the heart become uncoordinated. As a result, the chambers of the heart stop pumping in a coordinated and efficient way. (I've put an illustration showing electrical signals in a healthy heart and in a heart affected by atrial fibrillation on my website, AskDoctorK.com.)

Atrial fibrillation doesn't always cause symptoms, but most people who develop it can tell: The symptoms include palpitations, fainting, dizziness, weakness, shortness of breath and chest pain.

There are different treatments to restore a normal heart rhythm when you are having atrial fibrillation. When a patient of mine first develops it, I always try medication first. It's important to move quickly: The longer the heart is allowed to stay in atrial fibrillation, the harder it is to restore a normal heart rhythm.

Medicines often can restore a normal rhythm. When they don't work, another treatment option is electrical cardioversion. This treatment delivers a small electrical shock to the chest. The shock can "reset" the heart to a normal rhythm.

Unfortunately, many patients eventually redevelop atrial fibrillation. A number of different medicines can reduce the risk that atrial fibrillation will recur. Beta-blocker or antiarrhythmic drugs are used for this purpose. However, none of them is perfect; sometimes the irregular heart rhythm returns anyway. And all of the medications can have side effects.

Another relatively new approach to reducing the risk that atrial fibrillation will recur is called "radiofrequency catheter ablation." This procedure uses radio waves to destroy tissue in the heart that is triggering abnormal electrical rhythms. Another surgical procedure intentionally creates scars in the heart tissue; this blocks abnormal electrical signals from spreading throughout the heart.

These techniques can be quite effective, and they were not available when I graduated from medical school. But they don't always work to keep atrial fibrillation from returning, and they can cause side effects. So I don't consider them unless medicines haven't worked to keep atrial fibrillation from returning.

If, despite treatment, your heart repeatedly slips back into atrial fibrillation, doctors may allow the heart to stay in atrial fibrillation. When this happens, doctors attempt to slow the heart rate to help the heart work more efficiently. Medicines used to slow heart rate include beta blockers, calcium-channel blockers and digoxin.

When someone remains in atrial fibrillation, he or she generally needs to take blood-thinning drugs such as warfarin or aspirin to reduce the risk of blood clots. The uncoordinated beating of the heart causes blood to pool and form clots. These clots can travel through the blood and lodge in an artery, causing a stroke (and other complications). Blood thinners greatly reduce that risk.

(Dr. Komaroff is a physician and professor at Harvard Medical School. To send questions, go to AskDoctorK.com, or write: Ask Doctor K, 10 Shattuck St., Second Floor, Boston, MA 02115.)

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