THE EFFECT OF PULMONARY VEIN ISOLATION ON FRACTIONATION OF ATRIAL ELECTROGRAMS

Purpose: Targeting of complex fractionated atrial electrograms assessed during atrial fibrillation (AF) has been proposed for AF ablation. The effect of pulmonary veins isolation (PVI) on non-pulmonary AF substrate has not been investigated.

Methods: The study was performed in 5 patients (aged 64 ± 7 yrs) with long-standing persistent AF (23 ± 15 months) and LA dilation (46 ± 3 mm). CARTO fractionation map and re-map were obtained before and after PVI by purpose-made mapping device. Indices of fractionation of atrial electrograms (A-EGMs) were compared between corresponding pairs of points (distance<5 mm) evenly distributed outside the pulmonary veins antra.

Results: Total 109 pairs of points were collected with distance of 3.2 ± 1.0 mm. PVI resulted in decrease of fractionation in 74/109 (68%) while it increased in 35/109 (32%) of all analyzed sites. Overall reduction of A-EGMs fractionation was 120 ± 63 vs 148 ± 58 a.u., p=0.000002. At the same time, mean voltage decreased after PVI (0.64 ± 0.63 vs 0.51 ± 0.41 mV, p=0.03). However, change in fractionation was not related to change of voltage (r =-0.04, p=0.69). Fractionation before and after PVI correlated modestly (r=0.55, p<0.000001) and the regression line clearly differed from the line of identity (Figure). AF characteristics were not significantly affected during ablation in 1 patient while AF was converted into atrial tachycardia in 4 patients and terminated during further ablation (n=3) or electrically cardioverted (n=1).

Conclusions: 1) PV isolation significantly affects the AF substrate in LA areas far from ablation lesions; 2) Despite the decrease of fractionation in majority of sites, some areas show the opposite trend; 3) Fractionation re-map after PV isolation might be helpful in guiding the LA ablation in long-standing persistent AF.