Features April 2011 Issue

Be Prepared for AFib Recurrence Even After Ablation Treatment

Research shows that symptoms may return within a few years, but the duration and frequency of episodes are usually improved after treatment.

Atrial fibrillation (AF) is the most common sustained heart arrhythmia among Americans: More than two million of us suffer from the condition, and its incidence is predicted to double over the next four decades. Ten percent of hospitalizations in the U.S. are due to AF, and without effective treatment people with the condition can face unpleasant symptoms and poor quality of life.

While antiarrhythmic drugs are the frontline approach to treating AF, a minimally invasive procedure called catheter ablation can provide relief for people whose AF is resistant to drug treatment.

"The technique has the advantage of ensuring that AF sufferers avoid the side effects that can accompany medications," says Walid Saliba, MD, staff cardiologist and Director of the Electrophysiology Lab at Cleveland Clinic. "However, its long-term efficacy remains unknown." A recent five-year study (Journal of the American College of Cardiology, Jan. 11) suggests that the prospects of being "arrhythmia-free" for a long period of time following ablation are certainly not guaranteed.

Challenging to Treat

Dr. Saliba notes that AF is a challenging arrhythmia to treat. "While antiarrhythmic drugs or a procedure called cardioversion—in which an electric shock is applied to the heart—can be utilized to restore a normal heart rhythm, AF will recur and may persist," he says. "Antiarrhythmic drugs can sometimes have limited efficacy, and also can have significant potential side effects which limit their long term use." The limitations of drug therapy over the longer term have led to the development of non-pharmacological approaches to treat AF, one of which is ablation.

"AF is triggered by rapid and erratic electrical signals in the heart, and ablation procedures are designed to interrupt the conduction of electrical signals between the tissues that generate these signals, typically those situated around the pulmonary veins that drain from the lungs to the left atrium," Dr. Saliba explains. The technique involves having a catheter inserted through a tiny incision in the groin and threaded into a vein up to the heart, where the tip of the catheter is used to heat the muscle tissue to create a scar tissue in these targeted areas, isolating the pulmonary veins and preventing abnormal heart rhythms from circulating.

While ablation is generally effective, it’s possible for AF to recur after the procedure. "Early recurrence—that is, within two months of ablation—is typically facilitated by inflammation arising from the procedure, and usually subsides after the tissue has healed," Dr. Saliba says. "If AF recurs beyond the first two months, it’s considered to be late recurrence." The new study suggests that if symptoms are going to return, they will most likely do so within the first six to 12 months. The researchers found that 40 percent of the study participants were arrhythmia-free at one year after ablation, with 37 percent suffering no recurrence at two years.

Only about 29 percent of the patients who received a single ablation went five years without experiencing AF. However Dr. Saliba notes that the success of the procedure is measured by the degree of reduction of the overall AF burden (the frequency, duration and severity of the AF episodes), and not just by whether AF has recurred at all following the ablation. "The purpose of this procedure is to improve the quality of life by reducing the burden of atrial fibrillation, rather than just eliminating it altogether," he says

Why Might AF Recur?

Late recurrence isn’t uncommon after pulmonary vein isolation because even though doctors confirm that electrical conduction has been blocked during the procedure, the pulmonary veins can "re-connect" in the three to 12 months after catheter ablation.

"Other factors also can correlate with late recurrence," Dr. Saliba says, "including hypertension and underlying heart disease." In a previous study, 70 percent of patients with late recurrence of AF had hypertension, compared to 39 percent of patients who remained free of AF; 61 percent of patients who had late AF recurrence had high cholesterol, compared to only 30 percent who remained arrhythmia-free. "The size of the left atrium also has been shown to predict AF recurrence after ablation, as has older age, and the presence of persistent AF, in which each episode lasts more than seven days or requires a procedure called cardioversion—in which an electric shock is applied to the heart—to stop the AF," Dr. Saliba adds. Obstructive sleep apnea (OSA) also has been linked to low long-term success rates for ablation.

It’s thought that about 30 percent of patients undergo repeat ablation within the first year due to AF recurrence. In the study, 175 procedures were performed overall, with a median of two per patient. "Arrhythmia-free survival following the last catheter ablation procedure was 87 percent, 81 percent, and 63 percent at one, two and five years, respectively," Dr. Saliba observes. "This demonstrates that in selected patients with AF, ablation with repeat procedures as necessary provides acceptable long-term relief."