In silico biatrial fibrosis ablation improves atrial fibrillation outcome

FUNDING ACKNOWLEDGEMENTS: Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Medical Research Council Fellowship BACKGROUND: In DECAAF II, left atrial (LA) fibrosis ablation plus PVI did not improve AF outcome compared to PVI alone across the study cohort. We hypothesize that biatrial fibrosis ablation could improve AF ablation therapy outcome in a subset of patients with properties identified through a large virtual in silico trial. PURPOSE: To investigate the effects of anatomy, fibrosis distribution, and LGE-MRI threshold on ablation outcome using a virtual cohort of 4000 patients. METHODS: We constructed 1000 biatrial models from a statistical shape model and we mapped pectinate muscles, Bachmann’s bundle and fibers from an atlas. For each of the 1000 anatomies we applied a randomly selected fibrosis map from a library of 100 clinical maps. We then created four versions of each case by assigning one of four randomly selected right atrial (RA) fibrosis distributions with Utah grades 1-4 (Fig 1A), giving 4000 virtual patients. Four ablation approaches were applied to each patient model after 5 seconds of AF: PVI, PVI & LA fibrosis, PVI & RA fibrosis, PVI & biatrial fibrosis. LGE-MRI was thresholded for fibrosis ablation at either 1.2 or 1.32 image intensity ratio (IIR). The outcome was classified 5 seconds post ablation. RESULTS: Biatrial fibrosis ablation is more effective than LA ablation. For patients with high (Utah 4) RA fibrosis, biatrial fibrosis ablation increases AF termination compared to LA fibrosis ablation (Figs 1B & 2A: 62% vs 14%), this compares to cases with low (Utah 1) RA fibrosis (21% vs 14%). For patients with high LA (Utah 4) fibrosis, biatrial ablation is more effective than LA ablation (Fig 2B: 52% vs 19%), this compares to patients with low (Utah 1) LA fibrosis (17% vs 7%). Increasing IIR threshold for ablation decreases termination (LA fibrosis ablation: 15.8% termination at IIR 1.2, 11.0% at IIR 1.32; biatrial: 41.5% at IIR1.2; 20.3% at IIR1.32). Anatomy has a larger effect on biatrial ablation outcome (31.2% of outcomes change between anatomies) than on PVI only ablation outcome (20.0% change). CONCLUSION: Biatrial fibrosis ablation is superior to LA fibrosis ablation for cases with high RA fibrosis. Biatrial fibrosis distribution should be considered when targeting AF ablation therapy. [Figure: see text] [Figure: see text]