P882Correlation between late gadolinium enhancement assessment of atrial scar and low voltage areas detected by endocardial voltage mapping

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Background: Atrial fibrosis seems to correlate a higher risk of stroke and worse outcomes after catheter ablation in patients with atrial fibrillation (AF). Atrial scar can be non-invasively assessed with cardiac magnetic resonance (CMR), but this method still lacks thorough clinical validation. The purpose of our work was to evaluate the anatomical correlation between left atrial (LA) scarring/scar (?) assessed by late gadolinium enhancement (LGE) in CMR and low voltage areas (LVA) detected by endocardial voltage mapping. Methods: Single-centre prospective observational study that included 23 patients who underwent CMR with LGE assessment of atrial scar, previous to AF catheter ablation. Patients with inadequate CMR imaging (n=2) were excluded from the study, yielding a total of 21 selected patients for analysis. LVAs were identified by endocardial mapping with CARTO®, with a diagnostic cutoff of <0.5mV. Segments with low density of mapped points, preventing the identification/exclusion of LVAs, were excluded from the analysis. For all patients, LA was segmented in 6 regions, in which endocardial mapping of LVAs and atrial scar detected by LGE in the CMR were compared. Results: Population of 78% males, median age 62 (IQR 49-68) years old, 78% with paroxysmal AF and 72% who had previously underwent catheter ablation. Median LA volume indexed to body surface area was 55 (IQR 45-66) ml/m2 and CHA2DS2-Vasc=1 (IQR 1-2). The median number of mapped points was 242 (IQR 192-598). Sixty-nine LA segments (58%) were adequately evaluated, in which 52 (75%) had at least one LVA. The LA segments in which LVAs were more frequently identified were the superior and posterior walls (56% and 83%, respectively). LGE showed 93% sensitivity (CI 79-97%) and 73% specificity (50-89%) in identifying LVAs, with a positive predictive value of 89% (CI 80-94%) and negative predictive value of 76% (CI 57-88%). Conclusions:Left atrial scar assessed by late gadolinium enhancement in cardiac magnetic resonance showed a good sensitivity and adequate specificity in identifying left atrial segments with low voltage areas. Figure legend: A: Left atrial segmentation: 1 – superior wall, 2 – posterior wall, 3 – inferior posterior wall, 4 – superior septum above the fossa ovalis, 5 – inferior septum below the fossa ovalis, 6 – lateral wall. Example of a patient assessment: B – 4D (cardiac magnetic resonance) left atrial reconstruction (red) with late gadolinium enhancement identification of fibrosis (brown) in the posterior and superior wall, which correlate to low voltage areas in the endocardial mapping (C). Abstract P882 Figure.

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