Introduction: A left atrial appendage (LAA) occlusion devices deployed percutaneously using epicardial approaches have been proposed as an alternative to therapeutic anti-coagulation for stroke prophylaxis. Furthermore, epicardial exclusion of the LAA has shown promising results in decreasing the burden of atrial fibrillation (AF). However, it is unclear a role of LAA for initiation and maintenance of paroxysmal AF.
Hypothesis: Therefore, we examined the relationship between an initiation or maintenance of AF and the role of LAA.
Methods: 1) We induced AF and measured a duration of AF by rapidly pacing in LAA distal, LAA proximal and right pulmonary vein (RPV) in 9 swine. Pacing cycle length (p-CL) were 70, 90, 110 and130 msec in each site. 2) Among 9 swine, 5 swine were performed LAA isolation using radiofrequency ablation. After LAA isolation, we induced AF and measured a duration of AF again.
Results: 1)By p-CL of 90 msec, duration of AF with LAA distal-pacing was significantly longer as compared with RPV-pacing (33.4±41.4 msec versus 3.9±4.2 msec, p=0.008). By p-CL of 110 and 70 msec, duration of AF with LAA distal-pacing tended to be longer as compared with RPV-pacing (15.8±15.3 msec versus 5.0±7.1 msec, p=0.07, 33.0±58.4 msec versus 7.7±14.9 msec, p=0.06). 2) Radiofrequency ablation All 5 swine completely isolated all 5 swine. AF induction times by rapidly pacing after LAA isolation were decreased before LAA isolation (6 times versus 13 times). By all p-CL, duration of AF after LAA isolation was significantly shorter as compared to those with before LAA isolation. One swine was induced and maintained LAA-tachycardia after LAA isolation, however sinus rhythm maintained in other places except LAA.
Conclusions: LAA plays a role for initiation and maintenance of paroxysmal AF. Complete electrical isolation of LAA from left atrium by LAA exclusion system might be achieve freedom from AF.