Subgroup data called clinically meaningful
“This has huge implications going forward,” Dr. Marrouche maintained. In the context of a series of previous trials, including DECAAF I, which associated advanced fibrosis with higher risk of failing ablation, DECAAF II provides the groundwork for “where and how to ablate.”
Taken together, the DECAAF data suggest that there is no value in ablating advanced fibrosis. Due to the poor scar formation needed to reduce risk of AF recurrence, there are no benefits to outweigh the slightly greater risk of strokes and other adverse events observed among the intervention group in the DECAAF II trial, according to Dr. Marrouche.
“If the fibrosis is advanced, do PVI only,” he said.
However, if fibrosis remains at an early stage, defined by these data as stage II or lower, the data from DECAAF indicated that there is a benefit, according to Dr. Marrouche.
“DECAAF tells you to target early disease,” he said. Asked if he would now apply these data to treatment of patients with early fibrosis, he replied, “Yes, that’s what I am concluding.”
Several aspects of the design of DECAAF II, such as the use of a follow-up MRI to assess ablation at 3 months, were praised by Paul J. Wang, MD, director, Stanford Cardiac Arrhythmia Service, Stanford (Calif.) University, but he did not agree with Dr. Marrouche’s interpretation. This included the contention that scar formation was easier to achieve in patients with less atrial fibrosis.
DECAAF II is not a positive trial
Based on his reading of the correlation coefficients, expressed as an r value, which were 0.237 and 0.493 for the low- and high-fibrosis groups, respectively, “the difference in lesion formation in low- and high-fibrosis groups seems difficult to prove,” Dr. Wang pointed out.
In addition, “the authors suggest that the failure to achieve a good ablation lesion may account for the AFib recurrence,” said Dr. Wang, editor-in-chief of the American Heart Association’s Circulation: Arrhythmia and Electrophysiology. However, due to the many other potential variables influencing this risk, “this is difficult to show.”
Ultimately, despite a benefit observed among patients with a low level of fibrosis that was identified in an as-treated subgroup, “DECAAF II joins the numerous studies [evaluating the addition of an intervention relative to PVI alone] that have not achieved the primary endpoint,” Dr. Wang concluded.
An ESC-invited discussant, Christophe Leclercq, MD, chief of cardiology at Centre Hospitalier Universitaire, Rennes, France, made the same point. He said several previous studies have made the concept of achieving greater ablation to reduce AF recurrence “attractive,” but this “was not confirmed in DECAAF II.”
He also would not endorse MRI-guided ablation in resistant AFib among patients with early disease.
“There was a positive result observed in those with a low stage of fibrosis, but there were also more complications in those undergoing MRI-guided ablation,” he said.
Dr. Marrouche reports financial relationships with Abbott, which provided funding for this study. Dr. Wang had no disclosures. Dr. Leclercq reported financial relationships with Boston Scientific, Medtronic, Sorin Group, and St. Jude Medical.