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Feasibility of Pulmonary Vein Ostia Radiofrequency Ablation in Patients with Atrial Fibrillation: A Multicenter Study (CACAF Pilot Study

Feasibility of Pulmonary Vein Ostia Radiofrequency Ablation in Patients with Atrial Fibrillation: A Multicenter Study (CACAF Pilot Study
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  Feasibility of Pulmonary Vein Ostia RadiofrequencyAblation in Patients with Atrial Fibrillation:  AMulticenter Study (CACAF Pilot Study) GIUSEPPE STABILE, EMANUELE BERTAGLIA, *  GAETANO SENATORE, ◦ ANTONIO DESIMONE, FRANCESCA ZERBO, *  GIOVANNI CARRERAS,  ◦ PIETRO TURCO, PIETROPASCOTTO, *  and MASSIMO FAZZARI ◦ Casa di Cura S. Michele, Maddaloni (CE); Ospedale Civile di Ciri`e (TO); Ospedale Civile di Mirano (VE); Italy STABILE,G., ET AL .:FeasibilityofPulmonaryVeinOstiaRadiofrequencyAblationinPatientswithAtrialFibrillation: A Multicenter Study (CACAF Pilot Study)  Radiofrequency (RF) catheter ablation has been proposed as a treatment of atrial fibrillation (AF). Several approaches have been reported and successrates have been dependent on procedural volume and operator’s experience. This is the first report of amulticenter study of RF ablation of AF. We treated 44 men and 25 women with paroxysmal (n = 40) or  persistent(n = 29),drugrefractoryAF.Circularpulmonaryvein(PV)ostiallesionsweredeployedtranssep-tally, during sinus rhythm (n = 42) or AF (n = 26), under three-dimensional electroanatomic guidance.Cavo-tricuspid isthmus ablation was performed in 27 (40%) patients. The mean procedure time was215 ± 76 minutes (93–530), mean fluoroscopic exposure 32 ± 14 minutes (12–79), and mean number of RF pulses per patient 56 ± 29 (18–166). The mean numbers of separate PV ostia mapped and isolated per  patient were 3 . 9 ± 0 . 5, and 3 . 8 ± 0 . 7, respectively. Major complications were observed in 3 (4%) patients,including pericardial effusion, transient ischemic attack, and tamponade. At 1-month follow-up, 21 of 68(31%)patientshadhadAFrecurrences,ofwhom8requiredelectricalcardioversion.Afterthefirstmonth,over a mean period of 9 ± 3 (5–14) months, 57 (84%) patients remained free of atrial arrhythmias. RF ab-lation of AF by circumferential PV ostial ablation is feasible with a high short-term success rate. While the procedure and fluoroscopic exposure duration were short, the incidence of major cardiac complicationswas not negligible. (PACE 2003; 26[Pt. II]:284–287) atrial fibrillation, radiofrequency ablation, pulmonary vein Introduction In recent years, radiofrequency (RF) catheterablation has been proposed as an alternative todrugsinthemanagementofatrialfibrillation(AF).After the first attempts, 1 − 4 which tried to replicatethe surgical procedures, the discovery of the piv-otalroleofectopicactivitywithintheorificeorthemyocardial sleeve of pulmonary veins (PV) in ini-tiating and perpetuating AF, has changed the ther-apeutic endpoint of the procedures to the isola-tion of PV. 5 An electrophysiologic-guided 6 and ananatomical approach 7 have both been proposed.High success rates have been reported, dependentinpartonoperatorexperienceandproceduralvol-ume. The aim of our study was to evaluate the fea-sibility and safety of the anatomic approach to iso-late PV, in a multicenter design. MethodsPatient Population The 79 patients enrolled in this study hadsymptomatic AF unsuccessfully treated with Address for reprints: Giuseppe Stabile, M.D., Laboratorio diElettrofisiologia,CasadiCuraS.Michele,ViaAppia178,81024Maddaloni (CE), Italia. Fax: 0823/402474; e-mail: gmrsta- ≥ 2 antiarrhythmic drugs, and either monthlyepisodesofsustainedparoxysmalAF,orpersistentAF treated with ≥ 3 electrical cardioversions. Study Protocol All patients had given informed written con-sent to participate in the study. A detailed clin-ical examination, thyroid function tests, 12-leadelectrocardiogram(ECG),24-hourambulatoryECGrecording,chestXray,andtransthoracicandtrans-esophageal echocardiograms were routinely per-formed.Allpatientswereanticoagulatedwithwar-farin to achieve an international normalized ratio between2.0and3.0forthreeweeksbeforeRFabla-tion. All patients underwent the procedure while being treated with the most effective antiarrhyth-mic treatment. Anticoagulation and antiarrhyth-mic drugs were continued for ≥ 3 months after RFablation. The cardiac rhythm was monitored bytelemetryforatleast4hoursanda12-leadECGwasrecordedat12,24and36hoursaftertheprocedure.Clinical examinations and recordings of 12-leadECG were scheduled at 1, 2, and 4 weeks after dis-charge from the hospital, and monthly thereafter,for 12 months. Patients were instructed to obtainan ECG recording if they developed palpitations.All patients were followed for ≥ 3 months.284 January 2003, Part II  PACE, Vol. 26  ABLATION OF ATRIAL FIBRILLATION Mapping and Ablation Procedure Two quadripolar catheters were insertedthroughtherightfemoralandleftsubclavianveins,and were placed at the right ventricular apexand in the coronary sinus, respectively. The leftatrium and PVs were explored by a transseptalapproach. Real-time three-dimensional left atrialmaps were reconstructed with a CARTO nonflu-oroscopic navigation system (Biosense Webster),acquiring a minimum of 60 points. The ostium of the PV was identified by fluoroscopic visualiza-tion of the catheter tip entering the cardiac silhou-ette, with simultaneous impedance decrease andappearance of atrial potential. In patients in sinusrhythm, maps in the beginning of the procedurewereacquiredduringcoronarysinuspacing.Inpa-tients in AF, maps were acquired to measure theamplitude of local atrial electrograms. In 28 pa-tients RF pulses were delivered via an 8-mm tipcatheter, at a temperature setting of 60 ◦ C and RFenergy up to 100 W, and in the remaining 41 pa-tients, via a 4-mm cooled-tip catheter, at a temper-ature setting up to 45 ◦ C and RF energy up to 30 W.RFenergywasdeliveredfor60to120seconds,un-til the local electrogram amplitude had decreased by ≥ 80%. The ablation lines consisted of contigu-ous focal lesions deployed at a distance  ≥ 5 mmfromthePVostium,creatingacircumferentialline Figure1.  Voltage maps of peak-to-peak bipolar electrogram amplitude, in a posteroanterior view, before (A) and after (B) RF ablation. Red tags are the ablation sites. Note the marked decrease in electrogram amplitude (  < 0.1 mV) insideand near the lesions in the postablation map. of conduction block around each PV. Remappingwasperformedinallpatientsduringsinusrhythm,utilizing the preablation anatomic map for the ac-quisition of new points. A minimum of 5 pointsper each circumferential line was sampled. Theendpoint of the procedure was peak-to-peak bipo-lar potentials  < 0.1 mV inside the lesion, as deter-mined by local electrogram analysis and voltagemaps (Fig. 1). Statistical Analysis Continuousvariablesareexpressedasmean ± standard deviation (SD) and were compared us-ing a two-tailed Student’s  t  -test for paired and un-paired data. A value of P  <  0.05 was consideredstatistically significant. ResultsPatients Characteristics Theclinicalcharacteristicsofthepatientpop-ulation are summarized in Table I. Mapping and Ablation Procedure Left atrial mapping was performed during si-nusrhythmin42andduringAFin26patients.Themean number of separate PV ostia mapped per pa-tient was 3.9 ± 0.5 (5 ostia in 5 patients, 4 ostia in56, 3 ostia in 2, 2 ostia in 5). The mean procedure PACE,Vol.26  January 2003, Part II 285  STABILE, ET AL. TableI. Clinical CharacteristicsNumber of patients 69Age (years) 61 ± 9Sex (male/female) 44/25Type AF (paroxysmal/ 40/29persistent)Previous antiarrhythmic 2.8 ± 1 (range 2–5)drugs/patientsDuration of AF (years) 5.5 ± 3.5 (range 1–15)Left atrium diameter (mm) 49 ± (range 38-67)Left ventricular ejection 0.54 ± 0.14 (range 0.35–0.7)fractionPrevious cavotricuspid 27/69 (39%)isthmus ablationPrevious right atrium 5/69 (7%)compartmentalizationPrevious PVs isolation 2/69 (3%)Heart disease 43/69 (62%)Hypertension 35/69 (51%)Coronary heart disease 4/69 (6%)Valvular disease 3/69 (4%)Dilated cardiomyopathy 1/69 (1%) AF = atrial fibrillation. duration was 215 ± 76 min (93–530), fluoroscopicexposure32 ± 14minutes(12–79),andmeannum- ber of RF pulses per patient 56 ± 29 (18–166). Themean number of separate PV ostia isolated per pa-tient was 3.8  ±  0.7 (5 ostia in 5 patients, 4 ostiain 47, 3 ostia in 11, 2 ostia in 5). Major complica-tions were observed in 3 patients (4%), includingpericardialeffusion,transientischemicattack,andcardiactamponade.Thelattercomplicationdevel-oped while performing a selective left inferior PVangiography, before the beginning of the mappingand ablation procedure. Clinical Results During the first month of follow-up, 21 of 68patients (31%) had a recurrence of AF, of whom8 required electrical cardioversion to restore sinusrhythm. After the first month, during a follow-upperiod of 9  ±  3 months (5–14), 57 patients (84%)remained free of symptomatic atrial arrhythmias,including 90% of patients with paroxysmal AFand 75% of patients with persistent AF (ns). Discussion This is, to our knowledge, the first report of a multicenter study of the feasibility of PV isola-tion as a treatment of drug refractory AF. After theinitial, encouraging reports of the efficacy of thistreatment, two main clinical issues remained to beclarified: (1) are the results dependent on proce-dural volume and operator’s experience? 7 and (2)what is the actual efficacy of the therapy, since ithas been evaluated in uncontrolled studies, andusing mainly patients’ symptoms as an endpointof therapeutic success. 6 , 7 This multicenter studywas developed in an attempt to answer the firstquestion. Each center participating in the studyperforms  < 300 RF ablation procedures per yearand  < 50 CARTO-guided procedures per year. Itis noteworthy that procedural duration and fluo-roscopic exposure were relatively close comparedto larger studies using the anatomic 8 or electro-physiologic approach 6 to perform circumferentialPV ablation. In addition, the 84% success rate washigh when compared with 80% and 55%–93%,reported by Pappone et al., 8 and Haissaguerreet al, 6 respectively. Our rate of major complicationwassignificantlyhigherthanthatofPapponeetal.(4% vs 0.8%), though lower than Haissaguerreet al. (7.8%). This suggests that the complicationrate may depend on procedural volume and op-erator’s experience, as well as on the number of ablations performed per patient. The encouragingresults of this pilot study has prompted the de-sign a prospective, randomized, controlled study(CACAF), in which the efficacy of RF ablationin patients with drug refractory AF will be com-pared with antiarrhythmic drugs alone, and eval-uatedonthebasisofbothsymptomsandtranstele-phonic ECG recordings. Patient enrolment startedin March 2002, and we are hopeful that the resultsof CACAF will help answer the second persistentquestion. Study Limitations The study has two important limitations.First, the efficacy of the therapy was verified onthe basis of symptoms. However, brief episodes of atrial arrhythmias may be asymptomatic. Second,the efficacy of the ablation technique was studiedin patients treated with the most effective antiar-rhythmic regimen, and the impact of RF ablationalone was evaluated in only 6 patients (9%). Clinical Implications The results of our study suggest that circum-ferential isolation of PV ostia guided by a three-dimensional mapping system is feasible withacceptable procedural times and fluoroscopic ex-posure, even in medical centers performing fewprocedures. However, the relatively high inci-dence of major complications raises the issue of selection of candidates for the procedure, as wellas the importance of operator’s experience. 286  January 2003, Part II  PACE, Vol. 26  ABLATION OF ATRIAL FIBRILLATION References 1. Haissaguerre M, Jais P, Shah DC, et al. Right and left atrial radiofre-quency catheter therapy of paroxysmal atrial fibrillation. J Cardio-vasc Electrophysiol 1996; 7:1132–1144.2. Maloney JD, Milner L, Barold S, et al. Two-staged biatrial linear andfocal ablation to restore sinus rhythm in patients with refractorychronic atrial fibrillation. PACE 1998; 21(Pt.II):2527–2562.3. Pappone C, Oreto G, Lamberti F, et al. Catheter ablation of paroxys-mal atrial fibrillation using a 3D mapping system. Circulation 1999;100:1203–1208.4. Ernst S, Schluter M, Ouyang F, et al. Modification of the substratefor maintenance of idiopathic human atrial fibrillation. Circulation1999; 100:2085–2092.5. Haissaguerre M, Jais P, Shah DC, et al. Spontaneous initiation of atrialfibrillationbyectopicbeatssrcinatingfrompulmonaryveins.N Engl J Med 1998; 339:659–666.6. Haissaguerre M, Jais P, Shah DC, et al. Electrophysiological endpoint for catheter ablation of atrial fibrillation initiated from mul-tiple pulmonary venous foci. Circulation 2000; 101:1409–1417.7. PapponeC,RosanioS,OretoG,etal.Circumferentialradiofrequencyablation of pulmonary vein ostia. Circulation 2000; 102:2619–2628.8. Pappone C, Oreto G, Rosanio S, et al. Atrial electroanatomic remod-eling after circumferential radiofrequency pulmonary vein ablation.Circulation 2001; 104:2539–2544. PACE,Vol.26  January 2003, Part II 287
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