Atrial fibrillation, the most common heart rhythm abnormality, occurs when electrical irregularities in the heart cause its upper chambers to pump erratically, increasing the risk of serious complications such as congestive heart failure and blood clots. Treatments for atrial fibrillation include drugs to regulate heart rhythm, cardioversion (electric shock procedures), and catheter ablation. In catheter ablation, catheters inserted into the heart’s major blood vessels deliver tiny bursts of radio waves, which can correct irregular electrical impulses. But since catheter ablation is often accompanied by drug therapies and/or cardioversion, it has been unclear how effective it is when used alone.

In a new study appearing in the March 2, 2006 issue of the New England Journal of Medicine researchers found that 74% of participants who underwent catheter ablation had returned to normal rhythm without drug therapy after one year, compared with 4% of participants who underwent cardioversion alone.

About the Study

This study included 146 people with chronic atrial fibrillation. Half of the participants were assigned to have catheter ablation and the other half were assigned to have cardioversion. All participants took amiodarone, a rhythm-regulating drug, for six weeks before and three months after the study began. The researchers determined which participants were free from atrial fibrillation and atrial flutter (a less-serious rhythm irregularity) without rhythm-regulating drug therapy at 12 months.

At the end of one year, 74% of the participants in the ablation group and 58% of those in the cardioversion group were free from atrial fibrillation and atrial flutter without rhythm regulating drug therapy. However, since 77% of the participants in the cardioversion group had undergone catheter ablation due to recurrent atrial fibrillation, only 4% of those who had undergone cardioversion alone were in a normal heart rhythm without drug therapy at one year. The participants whose heart rhythms were corrected by ablation experienced improvements in the heart’s structure and functioning, and an improvement in their symptoms.

This study is limited because it excluded people over age 70 and those with certain coexisting conditions. So its results may not be applicable to all people with atrial fibrillation.

How Does This Affect You?

These findings indicate that catheter ablation alone can lead to long-term improvements in heart rhythm in certain people with chronic atrial fibrillation. This study is important, since drug therapies used to treat atrial fibrillation are associated with adverse effects, which may offset the benefits of procedures such as catheter ablation. This procedure could potentially improve the health of many of the more than two million Americans who suffer from atrial fibrillation.

But it is premature to recommend catheter ablation for all people with atrial fibrillation. This study was not representative of the whole population of people with atrial fibrillation, many of whom are elderly and have coexisting conditions. And although catheter ablation is generally well tolerated, it is not without its risks, which include stroke and other potentially-fatal complications.