Atrial fibrillation (AF) occurs when the top two chambers of the heart (the atria) beat rapidly and irregularly. The condition affects 2.5 million Americans and is especially common among the elderly. (10 percent of 80-year-olds have AF, compared to less than 1 percent of people younger than 55.) Because of the growing elderly population in the United States, the number of patients with AF is expected to increase by two and half times over the next 50 years.

Normally, the heart’s rhythm is controlled by electrical impulses that are generated by the heart’s pacemaker cells. These electrical impulses travel through the atria to a specialized electrical pathway called the AV node. The AV node serves as a time delay that causes the lower chambers of the heart (the ventricles) to contract after the atria contract. This delay gives the atria time to fill the ventricles with blood, which the ventricles then pump to other organs.

Atrial fibrillation occurs when an extra electrical signal “fires” prematurely from another location of the heart. (In over 90 percent of patients, this signal comes from the pulmonary veins, the tubes that bring oxygenated blood from the lungs to the left atrium.) This premature “firing” causes electrical impulses to rotate in a circle within the left atrium. This rotating wave of electrical activation is referred to as a wavelet. AF results from the continued perpetuation of multiple wavelets rotating randomly around the left atrium. When this happens, the atrium no longer contracts and the AV node gets bombarded by random electrical signals, which causes the left ventricle to beat rapidly and irregularly.

A patient with AF will experience a decrease in cardiac output (which leads to fatigue, shortness of breath, and difficulty exercising), a rapid and irregular heart beat (which leads to palpitations and light-headedness), and an increased risk of stroke. (When blood pools in an atrium that does not contract, clots may form and travel to the brain, causing a stroke.)

AF ablation via catheter is a procedure that has been highly effective in controlling AF and maintaining a patient’s normal heart rhythm. The procedure isolates the four pulmonary veins from the rest of the left atrium with small, controlled “burns” on the inside of the heart. These burns create an electrical barrier. The barrier makes it difficult for electrical impulses from the pulmonary veins to induce AF.

The day before the procedure, the patient will undergo an MRI or CT scan to help the physician visualize the patient’s unique pulmonary-vein anatomy. The patient will also undergo a trans-esophageal echocardiogram to ensure that there are no blood clots in the heart. AF ablation is performed while the patient is under general anesthesia. Several small catheters are placed carefully through veins in the groin and neck and carefully moved into the heart. An ablation catheter is used to place multiple small burns side by side to eventually encircle all four of the pulmonary veins within the left atrium. In special cases, when AF is permanent, additional lesions are placed strategically within the atrium to make the atrium less likely to fibrillate. The procedure usually takes three to four hours. The patient’s heart rhythm and catheter-access sites are monitored the day after the procedure. The second day after the procedure, the patient is usually sent home on Coumadin (an oral blood thinner) and an antiarrhythmic drug. Several days after discharge, the patient will return to the hospital to have his Coumadin dose adjusted. A follow-up visit with the physician who performed the AF ablation will occur two to three months later. During this visit, the Coumadin and antiarrhythmic medication are usually discontinued.

Several days before the procedure, the patient will stop taking antiarrythmic drugs and blood thinners such as Coumadin. A day before the procedure, the patient will receive a blood thinner (heparin) through an IV. After the procedure, Coumadin, Lovenox (another blood thinner), and an antiarrythmic medication are started again. (Because the heart may be “irritated” by the multiple small burns placed during the procedure, antiarrhythmic drugs are taken for two to three months after the procedure, until the heart has healed.) Lovenox is discontinued when the Coumadin reaches a theraputic blood level (this usually takes a few days). The Coumadin and the antiarrythmic drug are usually discontinued after two to three months.

The best candidates for AF ablation are those who 1) have AF that is highly symptomatic (this procedure is generally not performed on AF patients without symptoms), 2) have tried at least one antiarrhythmic drug that has failed or have reservations against taking antiarrhythmic medication long-term, and 3) have AF that is intermittent (the procedure may be helpful in patients with more persistent AF, but the success rate is not as high).

There are alternative options for the treatment of AF. A non-invasive treatment is a trial of antiarrhythmic drugs and cardioversion. If a patient with AF has another heart condition that requires surgery, a procedure called surgical maze may be performed during the surgery in order to correct the AF.

A successful AF ablation will correct both the heart rate and the rhythm disturbances caused by AF. Whether AF ablation reduces the risk of stroke has not yet been proven in studies. In patients with intermittent AF, AF ablation eliminates symptoms in 70 to 80 percent of patients for up to one year after the procedure. (Approximately 10 to 15 percent of patients may require a repeat ablation to remain AF-free for more than one year.) AF ablation for patients with persistent AF is effective, but the results are not as good as for intermittent AF. AF ablation should be performed by experienced operators who perform a large number of AF ablations. When performed by an experienced operator, the procedure is reasonably safe and effective.

Complications associated with AF ablation are rare but include some serious consequences:

• Cardiac perforation (less than 1 percent of the time)
• Stroke (less than 1 percent)
• Pulmonary vein narrowing (1 to 2 percent)
• Vascular complications at the sites where the catheters are inserted (5 to 10 percent)
• Slowed emptying of the stomach (gastropareis) (1 percent).
• Damage to the esophagus (much less than 1 percent)

Be sure to ask your physician about these risks and what measures are taken to minimize them during the procedure.

Continued exposure to short bouts of AF may cause electrical and structural changes in the atrial muscle that make it more likely to fibrillate. If AF is left untreated, these short bursts of AF may become longer and longer until AF is permanent. This process may take months or years to occur.

AF ablation with a catheter is an elective procedure that can be scheduled at the patient’s convenience.