758 Radiofrequency Catheter Ablation for Atrial Fibrillation PIERRE JAIS, M.D., DIPEN C, SHAH. M.D,. MELEZE HOCINI, M.D., TEIICHI YAMANE, M.D,, MICHEL HAISSAGUERRE, M.D., and JACQUES CLEMENTY, M,D. From the Hopital Cardiologique du Haut-L^veque, Bordeaux-Pessac, France Atrial fibrillation (AF) is a cotnmon and recurrent rhythm disorder u.sually poorly controlled by atitiarrhylh- mic drugs. It was shown recently that paroxysmal AF initiated by one or more foci is amenable to radical cure by radiofrequency (RF) catheter ablation. In a few cases, these initiating fwi were localized to the right atrium.'- whereas the vast majority of these foci are clustered at the ostium or within the first centimeters of the pulmo- nary veins (PVs).* Mapping of AF Initiation In our experience (and more recently that of many centers), >95% of these foci are from the PV, requiring transseptal access for tnapping and ablation and. there- fore, transseptal puncture in the absence of a permeable foramen ovale.'-' The article by Lee et al,'^ (from one of the most experienced laboratories for AF ablation) in this issue of the Jotuiutl addresses an important and practical ques- tion arising at every electrophysiologic study performed for AF ablation: Is the initiating factor located in the right or left atrium and, therefore, must a transseptal puncture be perfortned? The proposed algorithtii offers .some elements of re- sponse. It clearly demonstrates that when initiation is from ihe high right atrial (HRA) region (including the superior part of the crista terminalis [CT] and superior vena cava ISVC]). atrial activation at the His region is delayed as compared with that in sinus rhythm. On the contrary, atrial activity recorded by the Hisian catheter is anticipated (compared with HRA) when initiation is from the PV. Analysis of AF initiation with right-sided catheters allowed ihe authors to avoid useless transseptal punctures in 16 patients with SVC-CT foci in a series of 75 patietits. thus demonstrating the clinical interest of the algorithm. However, several issues need further discus- sion. The large proportion of SVC-CT foci (21%) has not been repoiied cl.sewhete.^''^ Previous data from the same group showed a much lower proportion (3/79 patients)." In our experience, only 3 patients of >250 had an SVC focus inducing AF (in contrast to atrial tachycardia); the J Cardiovasc Eleclrophysiol, Vol. 11. pp, 758-761. July 2000. Address for correspond ence; Pierre Jais. M.D.. Hdpital Cardiologique du Haut-L^vdque, Avenue de Magellan, 33604 Bordeaux-Pessac. France. Fax: 33-5-56-55-65-09; E-mail: jacques.clementy@pu.u- bordeau\2.fr total number of extra-PV foci was <5%. The low inci- dence of extra-PV foci initiating AF in other centers also suggests a somewhat different patient population. Analysis of HRA activity must be performed carefully because, in some cases, during eciopy right superior PV activity can be recorded from the right atrium, with such activity being very early and clearly occurring before atrial activity at the His-bundle level. This is an itnpor- tant point first described in 1997-' but which is still misleading, as reported in a recent issue of the Jottrnal.'' In sinus rhythm, two potentials are recorded from the posterior right atrium. Local right atrial activity is fol- lowed by the far-field right superior PV potential and vice versa from ihe right superior PV because, anatom- ically, the posterior right atrium is contiguous wilh the right superior PV. During initiation from this vein, the far-field right superior PV potenlial precedes local righl atrial activity. The risk, of course, is interpreting ihe far-field righl superior PV activity as originating from the right atrium and to ablate repetitively without efti- cacy but with the potential risk of" side effects. To over- come this limitation, careful analysis of the two different origins of the two signals is necessary. The near-field potential usually is sharper (of higher frequency) than [he far-tield potentiul. and pacing maneuvers trom the left atrium will modify their temporal relationship (resulting in fusion or widening). Another limitation of the proposed algorithm is that comparison of activation sequences in the HRA and His bundle is possible only for isolated ttianifest atrial pre-" mature beats or atrial premature beats initiating AF. In patients in whom there is only concealed PV ectopy at the time of exploration, no diagnoses can be made before crossing the septum. This phenomenon, which is seen in nearly 40% of patients, is pathognomic of an arrhythtno- genic PV, How to Predict Arrhythmogenic PV One of the major issues in AF ablation is to identify all potential arrhythmogenic PV. In the article by Lee et al.. 11% of patients had spontaneous AF initiation. In the other 89%. AF initiation required provocative tnaneu- vers. Unfortunately, the success rate of these maneuvers is limited, usually not exceeding 70%.'"" The l()0% success reported in inducing AF is likely to be due to patient selection. When one focus i.s identified, we cannot be sure that