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Use of image-guided technology to deliver a better ablation result for patients with persistent atrial fibrillation (Afib) achieved outcomes no different than convention pulmonary vein isolation alone, according to results of the randomized DECAAF II trial.

After a median 12 months of follow-up, atrial arrhythmia recurrence occurred in 43% of patients in the image-guided group versus 46.1% of controls (HR 0.95, 95% CI 0.77-1.17, P=0.63), said Nassir Marrouche, MD, of Tulane University School of Medicine in New Orleans, at the (ESC) virtual meeting.

He bristled, however, at the suggestion that the trial failed in its objectives: "This was not a failed trial," he told MedPage Today. "We have learned a lot from this study."

A subgroup analysis showed a trend toward better ablation coverage in the intervention group for patients with stage I or II atrial fibrosis at baseline, he explained.

"The results suggest that targeting atrial fibrosis in atrial fibrillation patients with low levels of fibrotic disease -- less than 20% -- may help improve ablation outcomes," Marrouche said. "In addition, the findings indicate that pulmonary vein isolation should remain the mainstream ablation strategy in atrial fibrillation patients with high levels of fibrosis -- those with more than 20%."

ESC spokesperson Kurt Huber, MD, of the Wilhelminen Hospital in Vienna, told MedPage Today: "I think this study is important because it shows us that if you perform ablation at the timepoint when the fibrosis in the atrium is lower than 20%, you have great chances to get a result with the ablation that holds on for a long time."

"If you have more fibrosis, it becomes complicated," he continued. "What we know is that in a patient with a lot of fibrosis, that even with two or three ablations there might not be any long-term effect. We can learn from this study that you may not want to wait too long to treat these patients."

The multicenter study previously reported that among Afib patients undergoing catheter ablation, atrial tissue fibrosis estimated by delayed enhancement MRI was independently associated with the likelihood of recurrent arrhythmia.

The DECAAF II trial tested the hypothesis that image-guided fibrosis ablation in addition to conventional pulmonary vein isolation would be superior to pulmonary vein isolation alone in improving ablation success rates in patients with persistent Afib.

The study included 843 patients with persistent Afib from 44 centers worldwide. Participants were randomized 1:1 to receive either pulmonary vein isolation plus image-guided fibrosis ablation or pulmonary vein isolation alone.

All patients underwent late gadolinium enhancement-MRI at baseline and approximately 3 months after treatment. Baseline images were used during the procedure in the intervention group to guide ablation of fibrotic tissue; operators were instructed to either cover or encircle the green areas on the images -- i.e., the fibrotic tissue -- in addition to pulmonary vein isolation. Operators in the control group were told to encircle only the pulmonary veins, without addressing additional lesions.

"These unique data provide us with the opportunity to better understand the effect of ablation on the left atrium and what parameters influence the formation of an ablation lesion," said Marrouche. He added that the study gives researchers a library of more than 800 patient atria, which could reveal considerable depth of knowledge that goes beyond this particular study.

Participants were followed for the primary endpoint of atrial arrhythmia recurrence -- Afib, atrial flutter, or atrial tachycardia -- for 12 to 18 months.

Patients were an average 62.1 years of age, and 78.8% were men. About 500 were found to have stage I or stage II fibrosis -- and this was the group that appeared to do better with the dual ablation therapy, Marrouche said.

The moderator of an ESC press conference that featured the study, Carlos Aguiar, MD, of Hospital Santa Cruz in Lisbon, Portugal, suggested that more research specifically aimed at the low fibrosis theory was necessary before clinicians can run with the results.

"I think the trial will help us determine two things, as it collected a vast amount of data on scarring in the atrium both before and after ablation: Imaging can help identify patients that will be more successfully treated with some type of atrial fibrillation ablation compared with those for whom ablation might be too late," he told MedPage Today.

"The other question is whether imaging can help the actual procedure and how it should be technically delivered and performed in order to guarantee better success," he said. "This study is opening more light into a field that has a lot of variation in practice and in results. If seems there is an opportunity to improve results through better selection."

And, said Huber: "I think we need more studies, and we also have different types of ablation techniques that need to be tested. This study doesn't give us a conclusion immediately or an impact on our clinical behavior."

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