ATRIAL LOW VOLTAGE AREAS: A COMPARISON BETWEEN ATRIAL FIBRILLATION AND
Aims Atrial fibrosis can promote atrial fibrillation (AF).
Electroanatomic mapping (EAM) can provide information regarding local
voltage abnormalities that may be used as a surrogate marker for
fibrosis. Specific voltage cut-off values have been reproducibly shown
to accurately identify fibrosis in the ventricles but they are not well
defined in atrial tissue. Methods Unicenter prospective study.
Consecutive patients with persistent AF referred for ablation were
included. EAM was performed with Carto3 mapping system (Biosense
Webster, Inc.). We recorded bipolar signals, first in AF and later in
sinus rhythm (SR) after electrical cardioversion. Two thresholds
delimited low-voltage areas (LVA): 0.5 and 0.3mV. We compared LVA
extension between maps in SR and AF in each patient. Results 23 patients
were included. Percentage of points with voltage lower than 0.5mV and
0.3 mV was significantly higher in maps in AF compared to maps in SR:
38.2% of points <0.5mV in AF vs. 22.9% of points
<0.5mV in SR (p<0.001); 22.3% of points
<0.3mV in AF vs. 14% of points <0.3mV in SR
(p<0.001). Areas with reduced voltage were significantly
bigger in maps in AF (0.5mV threshold, mean area in AF 41.3cm2 ± 42.5cm2
vs 11.7cm2 ±17.9cm2 in SR, p <0.001; 0.3mV threshold, mean
area in AF 15.6cm2 ±22.1cm2 vs 6.2cm2 ±11.5cm2 in SR, p
<0.001). Conclusion Using the same voltage thresholds, LVA
extension in AF is greater than in SR in patients with persistent AF.
These findings provide arguments for defining a different atrial
fibrosis threshold based on EAM rhythm.