365 ANALYSIS OF PIVOT POINTS AND SLOW CONDUCTION AREAS IN PATIENTS UNDERGOING ATRIAL FIBRILLATION ABLATION


 
 
 Little is known about progression of atrial fibrillation (AF) from paroxysmal to persistent form. Electrical remodeling may play a pivotal role in the arrhythmia transition. The aim of the study was the characterization of the atrial electrical substrate in patients suffering from AF.
 
 
 
 Twenty-seven patients were included in the study (14 with paroxysmal AF and 13 with persistent AF). Two simultaneous electroanatomical maps of the left atrium were collected using PentaRay catheter using the parallel mapping feature [first map during sinus rhythm and a second one with an extrastimulus from coronary sinus (CS)]. We analyzed the propagation of the wavefront and we identified zones of abnormal conduction: slow conduction (SC) corridors and pivot points (PP). SC corridors were defined by the slowing of conduction velocity; pivot points were zones in which propagation pattern changed the direction of 90° or more. Maximum delay between the recording dipoles located at the extremities of the PentaRay splines was calculated. At each of these sites, EGMs were collected and analyzed in terms of amplitude and duration. We checked if areas of abnormal conduction during sinus rhythm were present or they disappeared by delivering an extrastimulus from the coronary sinus.
 
 
 
 The average number of collected EGMs per map was 4790 ± 1333 (PAF 4829 ± 1407; PsAF 4745 ± 1402).
 Total abnormal conduction areas in the 27 patients were 62, 65% of which were slow conduction. Pivot points and slow conduction manifested a trend to cluster in some areas: both of them were mostly present at the ostia of pulmonary veins, in a specific segment between LAA ostium and mitral annulus and in the posterior wall. During sinus rhythm, pivot points were 29, while pacing from distal CS catheter the same zones showed normal conduction in 14 cases: they were still present in 60% in PAF group and 50% in PsAF. Slow conduction corridors, instead, show a trend to remain while pacing from CS: 76% in the first group and 78% in the second one.
 
 
 
 SC corridors are fixed alterations of atrial substrate, while pivot sites may be more dynamic entities: both of them may have a key role in remodeling atrial structures and atrial fibrillation progression and maintenance. These may represent future targets for AF therapy and prevention.
