1. The DECAAF II randomized controlled trial demonstrated that among patients with persistent atrial fibrillation, magnetic resonance imaging (MRI)-guided fibrosis-targeted ablation in addition to pulmonary vein isolation (PVI) did not reduce the recurrence of atrial arrhythmias compared to PVI alone.
2. Adverse outcomes were significantly increased among the MRI-guided ablation plus PVI group compared to the PVI only cohort.
Evidence Rating Level: 1 (Excellent)
Study Rundown: Recurrence of atrial arrhythmias, such as atrial fibrillation (AF), is common after ablation procedures. Given that left-atrial fibrosis seen on delayed-enhancement magnetic resonance imaging (MRI) was shown to be associated with atrial arrhythmia recurrence, it was hypothesized that targeting fibrosis using MRI may decrease recurrence following procedures. The DECAAF II trial investigated whether utilizing delayed-enhancement MRI to target atrial fibrosis in addition to performing the conventional treatment of pulmonary vein isolation (PVI) was superior in decreasing atrial arrhythmia recurrence compared to PVI alone in patients with persistent AF. This study was conducted in 44 centres across the United States, Europe, and Australia between July 2016 and January 2020. Patients were included if they had persistent AF (7 days or longer) and were undergoing their first atrial ablation procedure. Patients were randomized to either receive MRI-guided fibrosis ablation and PVI (n= 421) or PVI alone (n= 422). The primary outcome was the first confirmed recurrence of atrial arrhythmia. Atrial arrhythmia recurrence was not significantly reduced in the MRI plus PVI group compared to the PVI alone cohort (hazard ratio [HR]: 0.95 [95% CI: 0.77-1.17]; p= 0.63). There was no significant difference in the incidence of all three types of arrhythmias (AF, atrial flutter, and atrial tachycardia). Quality of life was also assessed using the Toronto Atrial Fibrillation Symptom Severity Scale; there was no significant difference in scores between cohorts (mean difference from baseline to 12 months: -0.38 points [95% CI: -1.23 to 0.47]). MRI-guided ablation plus PVI demonstrated a significantly increased risk of serious adverse events compared to PVI alone (2.2% vs 0%; p= 0.001); in particular, stroke appeared to be the most common significant adverse event. Overall, this randomized controlled trial demonstrated that MRI-guided fibrosis-targeted ablation plus PVI did not reduce the incidence of atrial arrhythmia recurrence compared to PVI alone; additionally, this procedure increased the risk of adverse events. One limitation of this study, however, is that the follow-up period was relatively short (up to 18 months), and perhaps a longer follow-up could reveal a significant difference between cohorts.
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