Catheter ablation offers an appealing option for patients with atrial fibrillation (AF) in whom rhythm control is desired. However, the success rate of the procedure remains somewhat dismal, with only 30% to 40% of persons achieving long term rhythm control. There are many theories as to why AF ablation may have limited success, including multiple sites of AF origination.
Typically, when an AF “ablation” is performed, the electrophysiologist enters the heart via the right-sided circulation (usually the inferior vena cava), does a trans-septal puncture (across the interatrial septum) under ultrasound guidance and enters the left atrium; then ablation lines are drawn with the radiofrequency catheter around the pulmonary veins. This is referred to as “pulmonary vein isolation” and electrically isolates the pulmonary veins, thought to be the electrical source of the AF, from the rest of the left atrium.
A new study reported at the European Society of Cardiology Scientific Sessions 2015 found that electrically isolating the left atrial appendage (LAA) may improve outcomes of AF ablation. There were 173 patients with long-standing persistent AF enrolled in the study; half were randomized to standard ablation plus LAA ablation and the other half received standard ablation. The mean age was 64 years, with >80% men.
After 12 months of follow-up, 56% of patients who received the LAA ablation were free of AF compared with 28% who underwent conventional ablation (p=.001). There were some patients in each arm who required another procedure on the appendage (27 originally in the appendage ablation group and 35 originally in the standard ablation group); average number of procedures on the appendage was 1.3. However, at 24 months, 76% of the appendage isolation patients were free of AF (lasting at least 30 seconds) compared with 56% of who had a standard ablation first.
Appendage isolation offers an exciting new adjunct for improving the success of AF ablations. One potential downside of the procedure is decreased mechanical action (contractility) of the appendage, which may increase thromboembolic risk over the long term. So, additional larger studies are definitely warranted before this becomes mainstream practice but this study uncovers an important potential mediator in the complex mechanism of the AF arrhythmia.
Di Biase L, et al "Effect of empirical left atrial appendage isolation on long-term procedure outcome in patients with long-standing persistent AF undergoing catheter ablation: results from the BELIEF randomized trial" ESC 2015.