18-06: AF Voltage as a Functional Marker for Atrial Fibrosis: Assessing the spatio-temporal correlation of low voltage regions during AF vs SR with late-gadolinium enhanced CMRI defined fibrosis in patients with persistent AF

Background: Endocardial voltage and late-gadolinium enhancement (LGE) are utilised as surrogate markers of fibrosis. Ablation of low voltage regions in PsAF has shown promising results, and LGE-CMRI defined scar guided ablation will be investigated in DECAAFII. We have reported the lack of correlation between AF voltage mapped over 1-2 AF cycles and LGE-scar. We hypothesised that increasing the sampling duration of AF voltage mapping allows for more accurate representation of the underlying structural substrate defined by LGE CMRI. Methods: Ten patients undergoing PsAF ablation underwent pre-procedural LGE-CMRI. Intra-procedural bipolar voltage mapping in AF was performed over 8s during 2 different AF epochs, where the mean peak-to-peak voltage (AF-V) at each site evaluated offline. A subset of patients underwent SR voltage (SR-V) mapping. Only data from the posterior LA wall as analysed as they represent best fidelity. The AF-V and SR-V in areas of LGE-scar, and areas of overlap of low voltage (LVA) (MPV <0.4mV) and LGE-scar, were quantified. Reproducibility of the AF-V (with varying sampling durations) over 2 distinct AF epochs was also evaluated.