Distinct atrial remodeling in patients with subclinical atrial fibrillation: Lessons from computed tomographic images

Cardiac implanted electronic devices (CIEDs) can detect atrial high-rate episodes (AHREs) and challenge current management of subclinical atrial fibrillation (AF).

To characterize the anatomic and functional remodeling of cardiac structures between patients with subclinical AF (SCAF) and clinical AF. The predictors for AHREs ≥6 min were also investigated.

We compared the atrial volume, dynamic function, and peri-atrial fat between 104 CIEDs (AHREs = 0, n = 12; SCAF, n = 66; CIEDs with AF, n = 26) and 40 paroxysmal AF patients who were planning for catheter ablation (AF for ablation) using 256-slice multidetector computed tomography for the duration of the AHREs. The maximal volume of the left atrium (LA) and LA appendage (LAA) were significantly smaller; the total emptying fraction (EF) and active EF of the LA and LAA were significantly better in the patients with SCAF than in those with clinical AF. Less peri-atrial fat (p < 0.001) and a greater LAA/ascending aorta (AA) Hounsfield unit (HU) ratio (p < 0.05) were noted in the patients with SCAF. Significantly increased volume reduced the total EF of LA and LAA and a reduced LAA/AA HU ratio (0.91 ± 0.18 vs 0.98 ± 0.03 vs 0.97 ± 0.05, p < 0.05) were demonstrated in patients with AHREs ≥6 min compared to those with AHREs <6 min and without AHRE. Multivariate analysis showed the reduced LAA/AA HU ratio is an independent predictor for the development of AHREs ≥6 min.

As compared to clinical AF, patients with SCAF show a more favorable LA remodeling process. Among the patients with device-detected AHREs, worse LA remodeling and a reduced LAA/AA HU ratio were associated with the occurrence of AHREs ≥6 min. These findings may provide an incremental value for understanding SCAF.