DECAAF II: MRI-Guided Ablation Not A "One-Size-Fits-All" Fix for Persistent AFib

Nassir Marrouche, MD

More aggressive treatment of atrial fibrillation (AF) may not always lead to improved outcomes, particularly in patients with more advanced AF, according to results of the DECAAF II study.

A global study conducted at 44 centers in 10 countries, results of the study suggest a strategy of pulmonary vein isolation (PVI) plus MRI-guided atrial fibrosis ablation did not result in a significant difference in arrhythmia recurrence but was associated with a greater rate of safety events when compared to PVI alone, including increased incidence of stroke.

“Simplicity is key. Don't ablate too much, especially at advanced stages,” said lead investigator Nassir Marrouche, MD, director of the Tulane Heart and Vascular Institute and The Research Innovation for Arrhythmia Discoveries (TRIAD) at Tulane University School of Medicine, in a statement. “Too much ablation is not helping our patients today. It is putting them at higher risk. This is a practice-changing finding from our study.”

Despite representing the most common form of arrhythmia and impacting millions across the world, a degree of uncertainty surrounds the pathophysiology of AF. In recent years, debate around the efficacy and safety of ablation procedures in patients with persistent AF has come to the forefront of discussion. Launched in 2015, the Efficacy of Delayed Enhancement MRI-Guided Ablation vs Conventional Catheter Ablation of Atrial Fibrillation (DECAAF II) trial was an investigator-initiated, multicenter, randomized clinical trial that enrolled 843 patients with symptomatic or asymptomatic AF with the intent of comparing a strategy with PVI plus MRI-guided fibrosis ablation against PVI alone.

Conducted in 44 academic and nonacademic medical centers in 10 countries, participants were recruited and randomized in a 1:1 ratio to PVI plus MRI-guided ablation or PVI alone, with 421 and 422, respectively, in each study arm. The overall study cohort had a mean age of 62.7 years, 21.1% were female, and 96.9% completed 90-day blanking period and contributed to the study’s efficacy analyses. The primary efficacy outcome of interest for the study was time to first atrial arrhythmia recurrence after a 90-day blanking period postablation. The primary safety outcome was a composite of stroke, PV stenosis, bleeding, heart failure, or death within 30 days postablation. As part of the study protocol, all patients underwent delayed-enhancement MRI before the procedure and at 3 months postablation to assess baseline and postablation scarring.

Upon analysis, results indicated there was not significant difference in arrhythmia recurrence observed with ablation plus PVI compared to ablation alone, with recurrence observed in 43% of patients undergoing ablation plus PVI compared to 46.1% among those receiving PVI alone (HR, 0.95 [95% CI, 0.77 to 1.17]; P=.63). In further subgroup analyses assessing for the primary efficacy outcome, investigators found the HR for ablation plus PVI was 0.88 (95% CI, 0.67-1.16) for patients with less than 20% baseline fibrosis and 1.09 (95% CI, 0.80-1.50) for those with 20% or greater fibrosis at baseline. In a prespecified secondary analysis, results suggested the mean decline in Toronto Atrial Fibrillation Symptom Severity Scale was 6.82 (95% CI, −7.52 to −6.08) points in the MRI-guided group and 6.44 (95% CI, −7.13 to −5.71) points in the PVI-only group at 12 months (mean difference, -0.38 [95% CI, -1.23 to 0.47]).

When assessing the primary safety outcome, the analysis demonstrated there was statistically significant higher occurrence of the composite safety outcome in the ablation plus PVI arm compared to the PVI-only arm, with events observed among 9 of the 403 in the ablation plus PVI group compared to 0 in the PVI only group (P=.001). Investigators pointed out ischemic stroke occurred among 6 patients in the fibrosis-guided ablation plus PVI group within 30 days postablation, but no stroke events were observed among those in the PVI-only group. Additionally, 2 deaths occurred in ablation plus PVI group, with the first occurring 5 days postablation and being of unknown cause and the second occurring 34 days postablation and due to 2 strokes after ventricular fibrillation.

“Atrial fibrillation procedures have become too complex over the years. We are ablating hundreds of thousands of people a year now, and we have been striving to do more and more ablation for the population with persistent or continuous AFib,” Marrouche said. “But our study shows that isn’t necessary, especially for those with more myopathy. Simple ablations can effectively treat these patients instead of going for extensive ablation to treat fibrotic areas that we struggle to control.”

This study, “Effect of MRI-Guided Fibrosis Ablation vs Conventional Catheter Ablation on Atrial Arrhythmia Recurrence in Patients With Persistent Atrial Fibrillation,” was published in JAMA.