Circumferential Pulmonary Vein Isolation To Treat Paroxysmal Atrial Fibrillation:Mechanistic Implication

Part I The effect of circumferential pulmonary vein isolation and ganglionated plexus ablation for pulmonary vein-originated atrial fibrillation:mechanistic implicationBackgrounds:Pulmonary veins(PVs)have been considered as the major sources of atrial fibrillation(AF),and circumferential PV isolation(CPVI)has emerged as the cornerstone for paroxysmal AF ablation.The mechanisms underlying AF initiation and PVI effectiveness remain unclear.Objective:To evaluate the impact of CPVI on PV firing in paroxysmal AF patients,and to explore the relationship between ganglionated plexus(GPs)and PV firing.Methods:Totally,121 paroxysmal AF patients who received CPVI therapy were enrolled.In Group 1(n=92),isoproterenol(ISP)and adenosine triphosphate(ATP)were co-administered to provoke PV firing before and after CPVI in patients with sinus rhythm.In Group 2(n=17),patients who had PV firing induced by ISP+ATP before CPVI were enrolled,pacing maneuvers were performed in addition to ISP+ATP provocation after CPVI.In Group 3(n=12),patients who had PV firing after PVI were enrolled,Adjacent GP ablation was performed and followed if necessary by additional PV ablation.Results:In Group 1,AF was induced in 47/81(58.0%)patients,while 43 of them originated from PV.After CPVI,only 16/88(18.2%)patients had AF induced(p<0.01),and only 2 of them had PV firing.In Group 2,various pacing maneuvers with ISP+ATP only induced PV-F in 1/17 patients after CPVI.In Group 3,in 8/12 patients,PV firing was terminated during GP ablation outside of the circumferential ablation line.In one patient,additional PV ablation resulted in cessation of PV firing and in the remaining three patients,firing could not be terminated by GP ablation or additional PVI.Conclusion:CPVI could markedly suppress the PV firing induced by ISP+ATP,suggesting a close relationship between PV firing and the atrium.Cardiac GPs maybe an important role.Part ? Pulmonary vein reconnection and atrial substrate in patients with and without recurrence after ablation of paroxysmal atrial fibrillationBackgrounds:Circumferential pulmonary vein(PV)isolation has been widely received as the cornerstone of paroxysmal AF ablation.Reconnection of PV conduction has been implicated as the predominant mechanism of clinical AF recurrence,but without enough clinical evidence.It is still unknown that,is sustained PV isolation required for freedom from clinical recurrence of AF?What is the role of atrial substrate in AF recurrence?Objective:To investigate the incidence of PV conduction recovery,and atrial substrate characteristics in patients with and without clinical recurrence of AF after ablationMethods:Phase-?,32 patients without clinical recurrence after PAF ablation were enrolled,electrophysiological study were performed to assess the incidence of PV reconnection.43 patients with clinical recurrence after ablation were enrolled as control group.The regions of gap were mapped and characterized in all of the reconnected PVs.Phase-?,36 paroxysmal AF patients who had no AF recurrence in more than 3 year's follow-up period after initial ablation therapy were enrolled as AF-free group,while 30 paroxysmal AF patients who had AF recurrence and received the second procedure were enrolled as AF-recurrence group.Detailed endocardial electrophysiology study was performed in each case,including PV-left atrium conduction checking,atrial ultra high-density substrate mapping.Results:Phase-I,in patients with clinical success,PV reconnection was recoredd in 29/32 of patients:31.2%reconnection in 4 veins,21.9%in 3 veins,31.2%in 2 veins,and 6.2%in 1 vein.While in patients with recurrence,40/43 patients had PV reconnected(p=1.0).No significant difference was found in left atrium-PV intervals(73.4±43.3 ms vs.61.9±31.8 ms,p>0.05).Phase-?,12/36 patients in AF-free group were found with no PV reconnection,while in AF-recurrence group,4/30 patients had no PV reconnection,(P>0.05).Significantly lower voltage was found in certain areas in AF-recurrence group(1.51mV vs.1.60mV;2.08mV vs.2.21mV,1.67mV vs.1.75mV,P<0.05,in anterior-,posterior-and superior-atrial segment,respectively,compared with AF-free group),as well as higher voltage variability were found in anterior-and posterior-segments in AF-recurrence group.Meanwhile,slower conduction velocity was found posterior-and superior-atrial segments in recurrence cases(1.41m/s vs.1.51m/s,1.41m/s vs.1.47m/s,respectively,compared with AF-free group).No significant difference in the above parameters was found in right atrial segments.Conclusion:A high incidence of PV reconnection was similarly observed in patients with and without recurrence of AF,suggesting that sustained PV isolation may not be required for freedom from clinical recurrence of AF.Substrate changes in left atrial substrate,including voltage and conduction velocity were possibly the important arrhythmogenic factors for AF recurrence after ablation in patients with paroxysmal AF.