Harvard Medical School Adviser by the Faculty of Harvard Medical School

Q:

My husband has an irregular heartbeat, a condition his doctor called "atrial fibrillation." He is 55 years old and in fairly good health, but I am worried that this could become a serious problem. Is this condition something that needs to be treated? If so, what are his options?

A:

The short answer to your question is yes, atrial fibrillation (AF) is a condition that can, and in many cases should, be treated. The best treatment, however, depends on many factors.

Before you can understand the treatment options, it will help to know what exactly AF is. AF occurs when the electrical signals in the heart, which are responsible for producing a regular heartbeat, go haywire. This causes the heart muscles to contract in an uncoordinated way. The result is an arrhythmia -- the fancy name for a heartbeat that is too slow, too quick or off rhythm.

Many people don't even notice that they have AF. Others may notice an irregular or rapid heartbeat or a "fluttering" sensation in the chest. People who have heart problems in addition to AF may experience fatigue, shortness of breath and exercise intolerance. Lightheadedness, confusion and sometimes even fainting may signal a substantial fall in blood pressure due to AF.

In some people, AF is not serious and requires minimal treatment. In others, AF can be dangerous if not treated. It can put people at risk for heart failure, angina and stroke. Luckily, successful treatments are available to help to prevent these complications.

There are three major strategies for treating AF: controlling the heart rate, restoring a normal heart rhythm, and using a medication called an anticoagulant.

A doctor's first choice in treating AF is often to try to control the heart rate. Medication can slow down the racing heartbeat in nearly all people with AF. The most useful drugs are beta blockers (such as propranolol and metoprolol) and calcium-channel blockers (such as diltiazem and verapamil).

When rapid treatment is in order, these medications can be injected into a vein, which produces an almost immediate effect. But in most cases, pills are used to maintain long-term heart rate control. Doctors usually adjust the dosage to achieve a resting heart rate of about 60 to 80 beats per minute, or 90 to 115 during moderate exercise.

Some people with AF may also benefit from rhythm control. The fastest and most effective way to restore the heart's rhythm is with an electric shock. Though the word "shock" seems scary, the process doctors use to treat AF involves only a small, brief pulse of electric current that is quite safe. And, since patients are given sedatives for this procedure, it is at most mildly uncomfortable. This treatment, officially called "electrical cardioversion," is most effective when used soon after the onset of AF, but many patients require a period of anticoagulant medication before they undergo cardioversion.

Doctors may also prescribe drugs to restore and maintain a person's heart rhythm. The choice of medication is tricky and may have severe side effects. Amiodarone is frequently the drug of choice. Other specialized drugs are available, but all of the rhythm-stabilizers can have side effects. That's why cardiologists are usually best suited to manage rhythm control, while primary care physicians are able to manage rate control.

It is important to note that most people with AF feel fine once their heart rate is controlled. But their well-being is deceptive, since they are still at risk for stroke. The risk is particularly high in older patients, in patients with a weakened heart muscle, high blood pressure or diabetes, and especially in patients with a previous stroke or mini-stroke (a "transient ischemic attack").

Anticoagulants (blood thinners) can reduce stroke risk in AF patients. Three choices are currently available. Aspirin is the simplest, safest and least expensive. But it is also the least effective, reducing the risk of stroke by only about 20 percent. Warfarin (Coumadin) reduces the risk of stroke by about 60 percent. It has been a mainstay of therapy for decades, but it is complicated to manage.

Now a new group of anticoagulant drugs is available. The FDA approved dabigatran (Pradaxa) for AF in 2010 and rivaroxaban (Xarelto) this November. They appear to be at least as safe and effective as warfarin and are much easier to use. Unfortunately, they are also much more expensive and are not suitable for all AF patients.

If you're thinking that AF is complicated, you're right. But the bottom line is straightforward and important. Your husband's doctors should: (1) check for things that might have triggered his AF; (2) get his heart rate under control, and discuss the pros and cons of trying to restore a normal heart rhythm; and (3) take steps to prevent a stroke. Think of these three steps as the ABC of AF.

(Submit questions to harvard_adviser@hms.harvard.edu.)

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