Atrial fibrillation: Common, serious, treatable

Sometimes the mechanisms that regulate the heart rate and rhythm go awry. Doctors call these disorders arrhythmias; they come in many varieties, but the most common sustained arrhythmia of all is atrial fibrillation (AF).

What is AF?

The human heart is divided into four pumping chambers. The two upper chambers are called the atria; they collect blood from the veins, then pump it into the two ventricles, larger and stronger chambers that propel the blood out from the heart to the rest of the body.

To function best, the atria should contract first, with the ventricles close behind.

When the heart is in its normal rhythm, the atria contract at steady, regular intervals. But in AF, the atria’s electrical signals occur much more rapidly, often 350 to 500 times per minute. At these rates, the muscle just can’t contract in a coordinated fashion. Instead of producing an atrial beat, the muscles just quiver (fibrillate) ineffectively. The ventricular rate is usually much faster than normal, and the rhythm is irregular, as is your pulse.

On the rise

AF is an old problem, but it’s becoming more common. The consequences are enormous, including almost 400,000 hospital admissions, 5 million office visits, and health care costs of over $6.5 billion a year. Even worse, AF increases the risk of stroke fivefold and almost doubles the risk of premature death. But there is good news, too: treatment can help.

Symptoms

The symptoms of AF vary widely. They tend to be more severe in older people and in those who also have structural heart or lung disease. People who are in good general health may not even be aware of the arrhythmia. Others notice a fluttering sensation in the chest or a rapid and/or irregular heartbeat.

The hazards of AF

Patients with AF are at risk for three major complications: heart failure, angina, and stroke.

AF reduces the heart’s pumping capacity by 10% to 30%. As a result, people with AF experience the fatigue, breathlessness, exercise intolerance, and swelling of the feet and legs that are so characteristic of heart failure. AF can also trigger the chest pain of angina or a heart attack in patients with coronary artery disease.

The other major complication of AF is stroke. AF quintuples the risk of stroke. It accounts for about 15% of all strokes and for nearly a quarter of all strokes in people ages 80 to 89.

The use of anticoagulants to prevent blood clots is one of the key priorities in managing AF. The others are slowing the heart rate and, in some patients, restoring a normal heart rhythm.

Reining in rapid rates

Medication can slow down the racing heartbeat in nearly all patients with AF. The most useful drugs are beta blockers (such as propranolol and metoprolol) and calcium-channel blockers (such as diltiazem and verapamil.

Patients who have chest pain or shortness of breath can receive rate-controlling medications intravenously; most respond in minutes to hours. Oral medications take longer to kick in, but most patients with sustained AF require long-term oral medications to maintain heart rate control.

Restoring normal rhythm

The fastest and most effective way to convert AF back to a normal heart rhythm is to jolt the heart with an electric shock. Electrical cardioversion sounds shocking, even drastic, but since it uses only a small, brief pulse of DC current, it is really quite safe — and since patients are sedated, it’s only mildly uncomfortable.

Drugs can also be used to convert patients from AF to a normal rhythm, and long-term medication may be needed to preserve a normal rhythm after successful electrical or pharmacological cardioversion; long-term anticoagulation is also generally necessary in many patients who are at risk for going in and out of AF. The choice of medication is tricky, and anti-arrhythmic medications can have severe side effects, even including serious arrhythmias. As a result, while primary care physicians often manage rate control, rhythm control is best guided by cardiologists. But for most patients with AF, the most important step of all is to use simple anti-clotting medications to prevent stroke.

There are procedures that use electricity to prevent future recurrences of AF. These can sometimes keep patients from having more attacks of AF.

Researchers are working hard to improve the management of AF. But for now, the tried and true will serve most patients well: slow the racing heart, consider restoring normal rhythm if symptoms persist, and reduce the risk of stroke by preventing clots.

Atrial fibrillation is an old problem, but it can be treated effectively, whether by standard therapy or new innovations.

January 2012 Update

Heart Disease: A guide to preventing and treating coronary artery disease

Most people fear heart disease — and with good reason: it’s the leading cause of death for both men and women. But something that people may not realize is that preventing this disease is often within their control. Most people who develop heart disease have one or more major risk factors that are within their power to change. These include lack of exercise, high blood pressure, and abnormal cholesterol levels. There are surefire ways to tackle these risk factors that you can include in... Learn more »