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Role of Pulmonary Veins Isolation in Persistent Atrial Fibrillation Ablation

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Background: The role of pulmonary veins (PV) isolation in patients with persistent atrial fibrillation (AF) is still debated. The aim of this study was to evaluate the adjunctive role of PV isolation in patients with persistent AF who underwent
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  Role of Pulmonary Veins Isolation in Persistent AtrialFibrillation Ablation: The Pulmonary Vein Isolationin Persistent Atrial Fibrillation (PIPA) Study GIUSEPPE STABILE, M.D., *  EMANUELE BERTAGLIA, M.D.,† PIETRO TURCO, M.D.,‡FRANCO ZOPPO, M.D.,† ASSUNTA IULIANO, M.D., *  FRANCESCA ZERBO, M.D.,†VINCENZO LA ROCCA, M.D.,‡ and ANTONIO DE SIMONE, M.D.‡ From the  * Clinica Mediterranea, Naples, Italy; †Ospedale Civile di Mirano, Mirano, Italy (VE); and ‡Clinica SanMichele, Maddaloni (CE), Italy  Background:  The role of pulmonary veins (PV) isolation in patients with persistent atrial fibrillation(AF) is still debated. The aim of this study was to evaluate the adjunctive role of PV isolation in patientswith persistent AF who underwent circumferential PV ablation (anatomical approach).  Methods:  We treated 97 consecutive patients presenting with drug-refractory persistent AF by ananatomical approach (group A, n  =  36, mean age  =  60  ±  8 years, 29 males) or an integrated approach(group B, n  =  61, mean age 59  ±  10 years, 48 males). In all patients, radiofrequency (RF) ablation was performed by means of a nonfluoroscopic navigation system, in order to anatomically create circumfer-ential lines around the PV. In group B, the persistence of PV potentials was ascertained with a multipolar circular catheter. If PV potentials persisted, RF energy targeting the electrophysiological breakthroughswas delivered to disconnect the PV. Past a 2-month period of observation, success was defined as absenceof any atrial tachyarrhythmia recurrence lasting  > 30 seconds.  Results:  Total procedure duration (220 ± 62 minutes vs 140 ± 43 minutes, P  < 0.001), fluoroscopy time(35 ± 15 minutes vs 17  ± 9 minutes, P  < 0.001), and RF delivery time (48 ± 22 minutes vs 27  ± 9 minutes,P  < 0.001) were significantly longer in group B than in group A. One cardiac perforation occurred in groupA. After 15  ±  9.1 months, 21 patients in group A (58%) and 34 patients in group B (56%) were free of atrial tachyarrhythmia recurrence (P  = 0.9). Conclusions:  In patients with persistent AF, who underwent an anatomical approach, electrophysio-logical confirmation of PV disconnection significantly increased the fluoroscopy and procedural times,without effect on the long-term outcomes. (PACE 2009; 32:S116–S119) atrial fibrillation ,  atrial fibrillation ablation ,  radiofrequency ablation ,  pulmonary vein ,  pulmonary vein isolation Introduction Catheter ablation is a well-established treat-mentofatrialfibrillation(AF).Whilethereisbroadconsensus that pulmonary vein (PV) isolation isthe target in patients with paroxysmal AF, its im-portance in patients with persistent AF is stilldebated. 1,2 Thus, different approaches have beenproposed to ablate persistent AF, including pro-cedures guided by electrograms, creation of linearlesions, ablation of autonomic ganglionated plexi,and sequential ablation. This study examined theadjunctive role of PV isolation in patients withpersistent AF who underwent circumferential PVablation. MethodsPatient Population The study included 97 consecutive patients(mean age = 59.5 ± 9 years; 77 males) who under- No conflict of interest to declare.Address for reprints: Giuseppe Stabile, M.D., Via Diaz 32,84100 Salerno, Italy. Fax: + 39089250810; e-mail: gmrstabile@tin.it went radiofrequency (RF) ablation for persistentdrug-refractory AF at three Italian medical cen-ters. In 36 patients (group A) a strictly anatomicalapproach was used, 3 and in 61 patients (group B)an integrated approach (anatomical ablation withelectrophysiological confirmation of PV discon-nection) 4 was adopted.Thestudyprotocolwasapprovedbyourinsti-tutional ethics committee, and all patients grantedtheir informed consent. Electrophysiological Studyand Catheter Ablation The study was performed after confirmationof the absence of intracardiac thrombi by trans-esophageal echocardiography. All patients wereorally anticoagulated to an international normal-ized ratio between 2 and 3, for  ≥ 1 month beforeablation. Heparin replaced the oral anticoagu-lants  ≥ 72 hours before ablation, and was dis-continued 4 hours before the procedure. Aftertransseptal puncture, a 5,000-IU intravenous bo-lus of heparin was administered, followed by C  2009, The Authors. Journal compilation  C  2009 Wiley Periodicals, Inc. S116 March 2009, Supplement 1  PACE, Vol. 32  PULMONARY VEIN ISOLATION IN PERSISTENT AF infusion or additional boluses to maintain anactivated clotting time  ≥ 250 seconds. The leftatrium and PV were explored by transseptal ap-proach in both group A and group B. Real-time three-dimensional left atrial maps were re-constructed, using a CARTO TM nonfluoroscopicnavigation system (Biosense Webster Inc., Dia-mond Bar, CA, USA). In the last 71 patients,reconstruction of the left atrium was supported by preacquired computed tomography scan im-age, imported into the electroanatomical systemand segmented by means of the dedicated Car-toMerge TM software (Biosense Webster Inc.) to re-construct the three-dimensional anatomy of theleft atrium and pulmonary veins, before its su-perimposition onto the CARTO electroanatomicmap. RF pulses were delivered, using a 3.5-mmNAVISTAR  THERMOCOOL  catheter system(Biosense Webster Inc.) with the upper temper-ature limited to 43 ◦ C, and RF energy to 42 W.RF energy was delivered until the electrogramamplitude was reduced by  ≥ 80%, for up to 120seconds. The ablation lines consisted of con-tiguous, encircling lesions, created 5 mm awayfrom each PV ostium. The ostium was consid-ered completely isolated when the amplitudeof   ≥ 3 electrograms recorded inside the encir-clement was (a)  < 0.1 mV, or (b) 80% lower thanthe amplitude recorded before ablation at thesame site.In group B, a second multipolar steerable cir-cular LASSO TM catheter (Biosense Webster Inc.)for circumferential PV mapping was used. In caseof persistent AF, electrical, external cardioversionwas performed, and the left PV was mapped dur-ing distal coronary sinus pacing, and right PVduring spontaneous rhythm. The catheter was in-serted into all PV and positioned orthogonal tothe PV axis as proximal as possible to the ostium.The persistence of PV potentials was ascertainedafter the anatomical ablation. If PV potentials per-sisted, the ablation procedure was performed bymeans of a fluoroscopic and electrophysiologicalapproach similar to that proposed by other au-thors. 5 Segments of the PV perimeter were tar-geted based on the earliest activation recordedfrom the circular catheter. When the site was ator inside the ostium, the power limit was set at30 W. The endpoint was elimination of PV mus-cle conduction distal to the ablation site, basedon the elimination or dissociation of the distal PVpotentials.Patients with conduction along the cavotri-cuspid isthmus underwent, in the same session,ablation of the inferior vena cavatricuspid annu-lus isthmus, after completion of the left atrialablation. Postablation Management All patients were discharged from the hospi-tal on oral anticoagulant, and continued antiar-rhythmic drug therapy for  ≥ 3 months. Clinicalexaminations were performed, and 24-hour am- bulatory electrocardiograms (ECG) were recordedat 1, 3, 6, 9, and 12 months of follow-up, and every6 months thereafter. Transesophageal echocardio-graphy was performed at 3 months to confirm theabsence of PV stenosis. Transthoracic echocardio-graphy was performed at 3 months to assess thequality of atrial contractility. In the event of stablesinus rhythm, anticoagulants and antiarrhythmicdrugs were discontinued after 3–6 months. An-tiarrhythmic drugs were continued in patients insinus rhythm who developed recurrences of AFwithin8weeks.Theprimaryendpointofthestudywas freedom from atrial tachyarrhythmias, lasting > 30 seconds, recorded by 24-hour ambulatory or12-lead ECG. As recurrences of AF within the first8 weeks after PV isolation may be transient, AFepisodesduringthisperiodwerecensored.IncaseofrecurrencesofAFafter8weeksoffollow-up,thetime of first recurrence was considered. Statistical Analysis Continuous variables are expressed asmeans ± SD and were compared by means of Stu-dent’s  t- test. Discrete variables were analyzed by χ 2 orFisher’sexacttest;relativeriskand95%con-fidence interval were calculated. A Kaplan-Meieranalysis with the log-rank test was used to deter-mine the probability of freedom from recurrentAF. A value of P  ≤  0.05 was considered statisti-cally significant. ResultsBaseline Characteristics There was no significant difference betweenthe two groups, except for the prevalence of pa-tients with dilated cardiomyopathy, which washigher in group A (Table I). Most patients pre-sented with idiopathic AF, or suffered from mildhypertension. A history of cerebrovascular acci-dent was present in four patients (4.1%). Procedural Observations Total procedure duration (220  ±  62 minutesvs 140 ± 43 minutes, P < 0.001), fluoroscopy time(35  ±  15 minutes vs 17  ±  9 minutes, P  <  0.001),and RF delivery time (48  ±  22 minutes vs 27  ± 9 minutes, P < 0.001) were significantly longer ingroupBthaningroupA.IngroupB,122of251PV(49%) were isolated at the end of the anatomi-cal ablation. After the adjunctive, LASSO-guided PACE,Vol.32  March 2009, Supplement 1 S117  STABILE, ET AL. Table I. Baseline Characteristics of the Two Study Groups ApproachPAnatomical Integrated Value Age, years 60 ± 7.6 59.3 ± 9.7 0.72Men/women 29/7 48/13 0.83Years of atrial fibrillation 4.4 ± 3.2 5.5 ± 4.3 0.23Left atrial diameter, mm 49.6 ± 8.2 46.9 ± 6.6 0.14Left ventricular ejection 55.5 ± 6.7 57.7 ± 5.4 0.12fraction,%Heart disease 28 (78) 40 (66) 0.2Hypertension 21 (58) 32 (52) 0.58Valvular 1 (3) 3 (5) 0.61Ischemic 1 (3) 3 (5) 0.61Dilated 5 (14) 2 (3) 0.05cardiomyopathy Values are means ± SD or numbers (%) of observations in thecorresponding group. ablation 243 of 251 PV (97%) were isolated. Af-ter anatomical ablation four patients in group Aand three patients in group B (P  =  0.26) returnedto sinus rhythm. No patient in group B returnedto sinus rhythm during the electrophysiologicallyguided ablation. In the remaining 90 patients, amean of 1.06 electrical cardioversions per patientwas required to restore sinus rhythm. Complications Cardiac perforation was the only complica-tion observed, which occurred in one patient(2.8%) in group A. Patient Follow-Up Allpatientswerefollowedfor ≥ 8months.Themean follow-up duration was 15.2 ± 10.9 in groupA and 14.9  ±  8 months in B (P  =  0.87). At 15  ± 9.1 months of follow-up, 21 patients in group A(58%) and 34 patients in group B (56%) were freefromatrialarrhythmiarecurrence(P = 0.9,relativerisk: 1.039; 95% confidence interval: 0.544–1.99;Fig. 1). In group A, five patients (24%) were in si-nus rhythm during treatment with antiarrhythmicdrugs, while in group B, 10 patients (29%) were insinus rhythm during treatment with antiarrhyth-mic drugs (P = 0.66). Discussion Our study showed that, in patients with per-sistent AF, electrophysiological confirmation of PVisolationsignificantlyincreasedtheproceduraland fluoroscopy times, though it did not improvethe long-term outcome. The discovery of the role Figure 1.  Survival free from recurrent atrial tachy-arrhythmias in each study group. of PV in the initiation and perpetuation of AF 6 hasopened the way to ablation treatment of AF. Thetwo main approaches 3,5 developed over the lastdecade are aimed at ablating the PV, PV ostia, orPV antrum, mainly from the posterior wall of leftatrium.However,withthe“electro-anatomicalap-proach” 3 PV isolation was achieved in  < 50% of targeted PV. 7 Nevertheless,  > 70% of patients re-mainedfreeofatrialarrhythmiasduringlong-termfollow-up. Several hypotheses have been formu-lated to explain the clinical success observed af-ter the delivery of RF in the area surrounding thePV ostia, separate from PV isolation: (1) modifica-tion of the substrate of PV tachycardia or “motherwaves,” disabling the reentry pathways; (2) dener-vation of parasympathetic afferences; (3) injury tothe Marshall’s ligament and Bachmann’s bundle,which are implicated in the initiation and main-tenance of AF; (4) promotion of electroanatomicalremodeling involving the posterior wall of the leftatrium, eliminating the substrate for AF.Two consensus statements 1,2 have recentlyemphasized the pivotal role of PV isolation whileperforming catheter ablation in patients withparoxysmal AF. In contrast, the role of PV iso-lation in patients with persistent AF is less clear.Oral et al. 8 reported 70% of patients with parox-ysmal and 22% of patients with persistent AF freefrom recurrent AF (P < 0.001) after segmental PVisolation.Theyconcludedthattheclinicalefficacyof PV isolation is much lower when AF is persis-tent than when it is paroxysmal. This hypothesiswas recently verified by the observations of Pra-tola et al., 9 who evaluated the long-term mainte-nance of intraprocedural end points of ablationprocedures in 20 patients with persistent AF instable sinus rhythm documented during a mini-mum follow-up of 2.5 years after the procedure.Their main finding was that common intraproce-dural endpoints, such as decrease in electrogramamplitude, PV disconnection, or exit block, per-sist in a limited proportion of patients, even whenS118 March 2009, Supplement 1  PACE, Vol. 32  PULMONARY VEIN ISOLATION IN PERSISTENT AF the long-term outcome is favorable. Different datahave been reported by Mantovan et al. 4 who com-pared the outcome of anatomical PV RF ablationwith that of an integrated approach (anatomicalablation with electrophysiological confirmation of PV disconnection) in 60 consecutive patients pre-dominantly (82%) suffering from paroxysmal AF.After 15.4  ±  7.4 months, 17 (57%) anatomicalgroup patients and 25 (83%) integrated group pa-tients were in stable sinus rhythm (P = 0.02). Ourresults, since addition of PV electrophysiologicalisolation to the anatomical ablation did not in-crease the percentage of patients free from atrialarrhythmias, seem to support the conclusions of Oral et al. and Pratola et al., and are strongly dis-cordant with findings reported by Mantovan et al.This discrepancy might be explained by the highproportionofpatientspresentingwithparoxysmalAF in the study by Mantovan et al., raising theissue of the effectiveness of acute PV isolation inpatientswithpersistentAF,whichappearstoonlyincrease the procedural and radioscopy times. Study Limitations Our study has several potential limitations.First, it was not randomized; instead, we enrolled97 consecutive patients who underwent AF abla-tion at three medical centers. In one center, theanatomical approach only was used, while theothers used the integrated approach. Although wecannot exclude that the operator might have in-fluenced the outcome, all operators had equiva-lent procedural experience and volume. Second,nearly 20% of our patients were treated with an-tiarrhythmic drugs. While this certainly had an ef-fectonthelong-termoutcomes,itprobablydidnotinfluenceourresults,sincetherewasnodifference between the two study groups. Third, arrhyth-mia recurrences were detected only by means of scheduled 12-lead ECG and 24-hour ECG moni-toring. Therefore, brief and asymptomatic recur-rences might have been missed, although thesewere probably rare in our population of drug-refractory, persistent AF. References 1. Natale A, Raviele A, Arenz T, Calkins H, Chen SA, HaissaguerreM, Hindricks G, et al., for the Venice Chart members. Venice ChartInternational Consensus Document on Atrial Fibrillation Ablation. JCardiovasc Electrophysiol 2007; 18:560–580.2. Calkins H, Brugada J, Packer DL, Cappato R, Chen SA, Crijns HJG,Damiano RJ, et al. HRS/EHRA/ECAS Expert Consensus statement oncatheterandsurgicalablationofatrialfibrillation:Recommendationsforpersonnel,policy,proceduresandfollow-up.HeartRhythm2007;4:816–861.3. Pappone C, Rosanio S, Oreto G, Monica T, Gugliotta F, VicedominiG, Salvati A, et al. Circumferential radiofrequency ablation of pul-monary vein ostia. Circulation 2000; 102:2619–2628.4. Mantovan R, Verlato R, Calzolai V, Baccellieri S, De Leo A, TurriniP, Pastore G, et al. Comparison between anatomical and integratedapproaches toatrialfibrillationablation:Adjunctive roleofelectricalpulmonary vein disconnection. J Cardiovasc Electrophysiol 2005;16:1–5.5. Haissaguerre M, Shah DC, Ja¨ıs P, Hocini M, Yamane T, Deisen-hofer I, Chauvin M, et al. Electrophysiological breakthroughs fromthe left atrium to the pulmonary veins. Circulation 2000; 102:2463–2465.6. Ja¨ıs P, Ha¨ıssaguerre M, Shah DC, Chouairi S, Gencel L, Hocini M,Cl´ ementy J. A focal source of atrial fibrillation treated by discreteradiofrequency ablation. Circulation 1997; 95:572–576.7. Stabile G, Turco P, La Rocca V, Nocerino P, Stabile E, De Simone A.Is pulmonary vein isolation necessary for curing atrial fibrillation?Circulation 2003; 108:657–660.8. OralH,KnightBP,TadaH,OzaydinM,ChughA,HassanS,Scharf,C,et al. Pulmonary vein isolation for paroxysmal and persistent atrialfibrillation. Circulation 2002; 105:1077–1081.9. Pratola C, Baldo E, Notarstefano P, Toselli T, Ferrari R. Radiofre-quency ablation of atrial fibrillation is the persistence of all intrapro-ceduraltargetsnecessaryforlong-termmaintenanceofsinusrhythm?Circulation 2008; 117:136–143. PACE,Vol.32  March 2009, Supplement 1 S119
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