Fibrosis ablation not superior to PVI, but promising in early stages of atrial myopathy
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In patients with persistent atrial fibrillation, a strategy of ablation based on MRI assessment of atrial fibrosis was not superior to pulmonary vein isolation for prevention of arrhythmia recurrence, researchers reported.
For the investigator-initiated DECAAF II study, presented at the European Society of Cardiology Congress, Nassir F. Marrouche, MD, professor of medicine and director of the TRIAD Center at Tulane University Heart & Vascular Institute, and colleagues randomly assigned 843 patients with persistent AF to the MRI-guided strategy based on atrial fibrosis or conventional pulmonary vein isolation.
“We performed an MRI scan before the ablation to assess the level of myopathy,” Marrouche said during a press conference. “We gave this to the operators in the MRI-guided group. We did not give it to the operators in the [pulmonary vein isolation] group.”
Patients underwent another MRI at 3 months to assess postprocedural scarring. “This is not only the largest persistent AF trial conducted, but also we looked at the quality of lesion formation. We collected all the data from the ablation parameters,” Marrouche said.
As Healio previously reported, in the original DECAAF study, delayed-enhancement MRI determined that atrial fibrosis level was a significant predictor of outcomes in patients with AF who underwent catheter ablation.
Patients were followed for 12 to 18 months. The primary outcome was recurrence of atrial arrhythmia, either AF, atrial flutter or atrial tachycardia.
In the intention-to-treat analysis, the primary outcome did not differ between the groups (HR = 0.95; 95% CI, 0.77-1.17; P = .63), Marrouche said during the press conference.
“We also saw an 11% improvement [with the MRI-guided strategy] in the early stages of disease, in patients who presented with less than 20% myopathy, but that wasn’t a significant difference,” he said.
Adverse events were higher in the MRI-guided group, particularly in patients with 20% or more atrial fibrosis, he said.
A finding “that will have huge implications going forward” is that in the as-treated analysis, “in the early stages of the disease, if you cover more of the myopathy, the better the outcome will be,” Marrouche said.
In that analysis, in patients with less than 20% atrial fibrosis, each 1 U increase in the level of fibrosis covered or encircled was associated with a 16% reduction in risk for the primary outcome (HR = 0.84; 95% CI, 0.73-0.96; P = .01), Marrouche said, noting the same was not true in patients with 20% or more atrial fibrosis (HR = 1.06; 95% CI, 0.92-1.24; P = .42).
“If you ablate fibrosis and cover it well, you can see better results,” he said, noting that in those with less than 20% atrial fibrosis, “there is good correlation between delivery of lesions and lesions formed. You don’t see this in the advanced stages of the disease. So that is a new challenge that we are facing: more myopathy, more disease and lack of lesion formation — the reasons why the lesions are not forming need to be studied.”
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Marrouche NF, et al. Hot Line: DECAAF II. Presented at: European Society of Cardiology Congress; Aug. 27-30, 2021 (virtual meeting).
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