Relationship between left atrial sphericity assessed by echocardiography and left atrial fibrosis in patients undergoing ablation for atrial fibrillation

The left atrial (LA) shape is the novel marker characterizing LA myopathy. Increased LA sphericity measured in magnetic resonance was shown to have relationship with LA fibrosis. Data on LA sphericity measured in echocardiography are sparse. The aim was to assess LA sphericity in relation to degree of LA fibrosis derived from electroanatomical mapping (EAM) in patients with atrial fibrillation (AF).

Patients (pts) with AF were studied with TTE before first ablation during sinus rhythm.

LA sphericity index (LASi) was calculated as the ratio of LA maximum volume (area-length method) to LA volume of sphere structured by maximum LA length from a 4- and 2-chamber views.

The EAM of LA was performed using Carto System. Low amplitude potentials area (LAPA) was quantitatively analysed and expressed as a percentage of LA surface using the cut-off <0.05 mV to detect sites of fibrosis.

LA parameters were compared between mild (LAPA<10%), moderate (LAPA 10-40%) and extensive (LAPA>40%) degree of LA fibrosis.

Study group consisted of 51 pts (74,5 % males, mean age 56±10 years).

The median [Q1-Q3] LA volume index (LAVi) was 37.1 [28.9 – 52.6] mL/m².

The median [Q1-Q3] LASi was 0.82 [0.71 – 1.06].

The LAPA ranged from 2 to 77 percent of LA surface.

The Spearman’s correlation analysis showed a significant correlation between LASi and LAPA (0.59, p<0.001).

Increased LA sphericity was observed in LAPA≥10% whereas increased LAVi in LAPA≥40% subgroup (table).

The LASi derived from TTE correlates well with the extent of LAPA, thus might be a simple and useful parameter of LA geometric remodeling associated with increased LA fibrosis.

LA geometry in relation to fibrosis