Image-guided fibrosis ablation in addition to pulmonary vein isolation (PVI) did not improve ablation success rates in patients with persistent atrial fibrillation (AFib) compared with PVI alone, according to investigators presenting findings from the DECAAF II trial at ESC Congress 2021. However, as-treated analyses showed that covering low-grade atrial fibrosis with ablation lesions did lead to a significant reduction in atrial arrhythmia recurrence.

The trial enrolled 843 patients (median age 62 years, 78.8% men) with persistent AFib from 44 centers around the world. Participants were randomized to receive either PVI plus imaging-guided fibrosis ablation (intervention group) or PVI alone. All patients underwent late gadolinium enhancement (LGE)-MRI at baseline prior to ablation and then approximately three months after. The 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 PVI. Operators in the control group were instructed to only encircle the pulmonary veins, without adding additional lesions. The three-month MRI evaluated the formation of lesions secondary to ablation. The primary endpoint was atrial arrhythmia recurrence for 12 to 18 months.

Overall results found baseline fibrosis was predictive of AFib ablation outcomes, especially at higher fibrosis levels – findings that confirmed the results of the initial DECAAF study. In the intention-to-treat analysis, no statistically significant difference was observed in the primary endpoint between groups in the total study population. Atrial arrhythmia recurrence occurred in 43% of patients (n=175) in the intervention group and 46.1% of patients (n=188) in the PVI-only group.

Subgroup analyses suggested a trend towards a lower rate of atrial arrhythmia recurrence in the intervention group for patients with stage I or II fibrosis at baseline. As-treated analyses examining atrial arrhythmia recurrence according to the proportion of targeted and covered fibrosis (as assessed by the three-month MRI) found a significant benefit of substrate ablation in patients with stage I or II fibrosis at baseline. However, researchers observed no benefit of image-guided fibrosis ablation on atrial arrhythmia recurrence in patients with stage III or IV stage fibrosis at baseline. They also noted that the rate of complications, including post-ablation stroke, was higher in the image-guided ablation group but was mainly driven by patients with high levels of fibrosis at baseline.

"The results suggest that targeting atrial fibrosis in AFib patients with low levels of fibrotic disease (less than 20%) may help improve ablation outcomes," said principal investigator Nassir Marrouche, MD. "In addition, the findings indicate that PVI should remain the mainstream ablation strategy in AFib patients with high levels of fibrosis (more than 20%)."

Clinical Topics: Arrhythmias and Clinical EP, Noninvasive Imaging, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Magnetic Resonance Imaging

Keywords: ESC Congress, ESC21, Arrhythmias, Cardiac, Pulmonary Veins, Magnetic Resonance Imaging, Catheter Ablation, Atrial Fibrillation, ACC International

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