Atrial average conduction velocity in patients with and without paroxysmal atrial fibrillation

To evaluate intra-atrial conduction delay in patients with atrial fibrillation (AF) via calculation of conduction velocities (CVs) of the right and left atria.

Electroanatomic mapping was performed during sinus rhythm, in the right atrium (RA) in eight patients with paroxysmal AF, in 12 controls with atrioventricular nodal re-entrant tachycardia (AVNRT) and in the left atrium (LA) in additional 16 AF patients. Three-dimensional maps of activation sequences of the RA and LA were obtained. Local CVs were specifically calculated in the direction of wave-front propagation on the activation maps by using 3-dimensional coordinates and local activation times of triads of sites. Average CVs of each atrium and each of 8 predefined RA and LA regions were calculated.

During sinus rhythm, the average CVs of the RA were significantly slower (P<0·05) in the AF group (0·60 ± 0·12 m s^-1 ) than in the controls (0·83 ± 0·13 m s^-1 ). The average CVs of the RA basal, septal and annulus regions were significantly slower than the corresponding regions in controls (P<0·05). In patients with AF, the average CV of the LA was 0·51 ± 0·11 m s^-1 , which is significantly slower than that of the RA and than that of LA as previously reported (P<0·05).

Compared to patients with AVNRT, patients with AF are associated with conduction delay in both atria with the delay being more marked in the LA than in the RA, which suggests the involvement of conduction disturbances in the genesis and/or perpetuation of AF.