Abstract Body (Do not enter title and authors here): Background: There are currently no established non-invasive indices for elevated left ventricular (LV) filling pressure in patients with atrial fibrillation (AF). Remote dielectric sensing (ReDS) is a novel non-invasive electromagnetic energy-based technology that quantifies total lung fluid, enabling the monitoring of volume status in patients with heart failure.

Hypothesis: ReDS might be a useful non-invasive tool for the estimation of LV filling pressure even in patients with AF.

Aims: We sought to clarify the utility of ReDS for estimating LV filling pressure in patients with AF.

Methods: We prospectively investigated patients with AF in whom mean left atrial pressure (LAP), which represents LV filling pressure, was directly measured during catheter ablation for AF. ReDS measurements were conducted the day before ablation. The association between ReDS readings and directly measured LAP was evaluated. Elevated LAP was defined as LAP ≥15 mmHg.

Results: A total of 61 patients were included (median age 66 [interquartile range 62–74] years, 38% female). Among them, 26 patients had elevated LAP. ReDS was positively correlated with directly measured LAP (r = 0.363, P = 0.004). Receiver operating characteristic curve analysis for the prediction of elevated LAP demonstrated that the best cut-off value of ReDS was 30%, with a sensitivity of 65%, specificity of 69% (Figure A). The LAP was significantly higher in patients with ReDS ≥30% than in ReDS <30% (median 15 [interquartile range 11–20] vs 11 [8–15] mmHg, respectively, Figure B). ReDS was an independent predictor of elevated LAP by multivariate logistic regression analysis, regardless of whether ReDS was analyzed as a continuous or a categorical variable (ReDS ≥30% or ReDS <30%).

Conclusions: Our results suggest ReDS could be a valuable marker of elevated LAP, representing LV filling pressure, even in patients with AF.