Left atrial wall thickness is associated with the low-voltage area in patients with paroxysmal atrial fibrillation.

Abstract

To identify a potential morphological marker of remodeling and electrophysiological dysfunction, we investigated if low wall thickness is associated with low-voltage areas (LVAs) in the left atrium. Wall thickness was measured by computed tomography and LVA (% area with bipolar voltage < 0.5mV) by voltage mapping in 43 paroxysmal AF patients. The left atrium was divided into five segments: septal wall, anterior wall, roof wall, posterior wall, and bottom wall in regional analysis. Left atrial wall thickness and LVA were 3.2 ± 0.6mm and 14% ± 9%, respectively. Multivariate analysis identified left atrial wall thickness and volume as independent determinants of left atrial LVA (thickness, standardized β - 0.374, 95%CI - 23.289 to - 4.534, P = 0.005; volume, standardized β 0.452, 95%CI 0.049-0.214, P = 0.002). In regional analysis, significant LVA (> 10% of segment surface area) was observed in 123 of 215 segments (57%). Segments in the low tertile of wall thickness (< 1.76mm) had larger LVAs compared with segments in middle (1.76-2.14mm) and high tertiles (≥ 2.14mm) (low tertile, 20.3% ± 14.9%; middle tertile, 12.6% ± 11.2%; high tertile, 12.5% ± 12.1%; low vs. middle tertile, P = 0.001; low vs. high tertile, P = 0.001). Area under the receiver operating curve of wall thickness was 0.706 for prediction of significant LVA. A thickness cut-off of 1.90mm yielded 62% sensitivity, 73% specificity, 75% positive predictive value, and 59% negative predictive value for significant LVA. A thin left atrial wall is an independent predictor of LVA in patients with paroxysmal AF.