MRIs indicate which Atrial Fibrillation patients might benefit most from catheter ablation

by Bruce Sylvester: Newly developed contrast MRI can help physicians predict which atrial fibrillation people have the best chance of benefiting from catheter ablation, researchers reported on Feb. 4, 2014 in JAMA, the Journal of the American Medical Association.

Atrial fibrillation is the most common type of arrhythmia. When medications fail, A-fib can often be treated with catheter ablation. But catheter ablation is not effective in all cases. To date, there has been no way to predict well who will benefit from the procedure.

“Catheter ablation is a very effective treatment for atrial fibrillation, but it can’t cure everyone,” said lead investigator David Wilber, MD, George M. Eisenberg Professor of Cardiovascular Sciences in the Department of Medicine of Loyola University Chicago Stritch School of Medicine in Maywood, Illinois. “The findings from this study suggest there may be patients whose scarring is so advanced that ablation in its current form is much less likely to be effective as a single procedure. In such cases, patients, in consultation with their physicians, may decide to forgo ablation, or be prepared to have more than one procedure to control the arrhythmia.”

The investigators enrolled 329 subjects in the United States, Europe and Australia. Each had a catheter ablation. Less than 30 days before ablation, each subject had a new type of imaging test called delayed enhancement-magnetic resonance imaging (DE-MRI) of the upper chamber of the heart (left atrium). The imaging revealed scarring, or atrial fibrosis, of the wall of the left atrium.

The researchers excluded 69 subjects in the final analysis, either because the DE-MRI was of inadequate quality or because patient-contact was lost during follow-up. Data on 260 subjects was evaluable.

Pre-ablation DE-MRI showed the amount of scarring in the left atrium; scarring ranged from Stage 1 (covering less than 10 percent of the atrial wall) to Stage 4 (covering more than 30 percent of the atrial wall).

After 475 days of follow up, 85 percent of patients with the least-severe Stage 1 scarring achieved no recurrent arrhythmia. The same was true for 64 percent for subjects with Stage 2 scarring, 54 percent with Stage 3 scarring and 31 percent with Stage 4 scarring.

Each subject also had a DE-MRI 90 days after their catheter ablation, to see how effective the ablation had been in removing scar tissue. Such findings could help guide physicians if and when additional ablations are necessary, Dr. Wilber said.

Patients unlikely to benefit from ablation still could be treated with medications, and in some circumstances with pacemakers, Dr. Wilbur added.