The influence of the external structures in atrial fibrillation patients: Relationship to focal low voltage areas in the left atrium

- Low voltage areas (LVAs) are associated with maintenance of atrial fibrillation (AF).
- Enhanced CT demonstrated 3 compressed regions to left atrium (LA) in AF patients.
- Anatomical compressed region demonstrated a spatial relationship to the LVAs.
- Distance to near external structures was the only predictive factor for the existence of LVA.
- Anatomical factors may have an influence on some progressive factors for electrical remodeling.

IntroductionLeft atrial (LA) low voltage areas (LVAs) are suggested as an important factor for maintaining atrial fibrillation (AF). The relationship between focal LVAs and anatomical contact is still unclear.MethodsThirty paroxysmal AF (PAF) and 30 persistent AF (PsAF) patients underwent high density voltage mapping during sinus rhythm before any radiofrequency applications were performed. The relationship between the LVA (< 0.5 mV) and contact area (CoA) demonstrated by enhanced CT and the distance to near external structures were investigated.ResultsThe anterior region, posterior wall and left pulmonary vein (LPV) antrum were the three most frequent LVA sites that corresponded to CoA sites, and LVAs mostly overlapped with CoAs (PAF 47/61: 77%, PsAF 63/74: 85%). In the PAF group, patients with posterior-LVAs had a shorter distance to the vertebrae than those without (2.8 ± 1.1 vs. 4.4 ± 1.9 mm; P = 0.0086). The distance to the vertebrae was the only predictive factor of the existence of a posterior-LVA and the cut-off value was ≤ 2.9 mm (P < 0.0001). Similarly, an LPV-LVA also had the same results (2.0 ± 0.5 vs. 2.7 ± 0.8 mm, P = 0.0127) and the cut-off value was ≤ 2.6 mm (P = 0.0391). In contrast, the PsAF patients had no difference in the distance when compared to the existence of an LVA.ConclusionsAnatomical CoAs demonstrated a spatial relationship to the LVAs in AF patients. In PAF patients, the distance to near external structures in the posterior region was a predictive factor for the existence of an LVA and may have had some influence on maintaining AF, while in PsAF patients no relationship was suggested.