Ebook Practical approach to catheter ablation of atrial fibrillation: Part 1

(BQ) Part 1 book Practical approach to catheter ablation of atrial fibrillation presents the following contents: Introduction and historical perspective, ablation program planning, mapping, imaging, and guidance systems.

A Practical Approach

to Catheter Ablation

of Atrial Fibrillation

Baltimore, Maryland

P IERRE J ẠS , MD

Professor Department of Cardiology Université Victor Segalen–Bordeaux 2 Hơpital Cardiologique du Haut Lévèque Cardiology Department

Ridgewood, New Jersey Professor of Medicine Columbia University College of Physicians & Surgeons New York, New York

Acquisitions Editor: Frances R DeStefano

Managing Editor: Chris Potash

Marketing Manager: Kimberly Schonberger

Project Manager: Bridgett Dougherty

Senior Manufacturing Manager: Benjamin Rivera

Creative Director: Doug Smock

Compositor: Aptara Inc.

© 2008 by LIPPINCOTT WILLIAMS & WILKINS

All rights reserved This book is protected by copyright No part of this book may be reproduced in any form or by any means, including photocopying, or utilized by any information storage and retrieval system without written permission from the copyright owner, except for brief quotations embodied in critical arti- cles and reviews Materials appearing in this book prepared by individuals as part of their official duties as U.S government employees are not covered by the abovementioned copyright

Printed in the USA

Library of Congress Cataloging-in-Publication Data

A practical approach to catheter ablation of atrial fibrillation / editors, Hugh Calkins, Pierre Jạs,

The authors, editors, and publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accordance with current recommendations and practice at the time of publica- tion However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any change in indications and dosage and for added warnings and precautions This is particu- larly important when the recommended agent is a new or infrequently employed drug

Some drugs and medical devices presented in this publication have Food and Drug Administration (FDA) clearance for limited use in restricted research settings It is the responsibility of the health care provider to ascertain the FDA status of each drug or device planned for use in their clinical practice.

10 9 8 7 6 5 4 3 2 1

To Alice, Rachel, and Josh, whose encouragement and support made all this effort possible

—JS

To Beth, Emily, Eliza, and Daniel

—HC

C O N T E N T S

Contributing Authors xi Preface xxiii

I Introduction and Historical Perspective 1

1 Indications for Atrial Fibrillation Ablation and Consensus Recommendations 3

Hugh Calkins

2 Nonpharmacological Therapy for Atrial Fibrillation:

An Historical Overview 11

David A Spragg, Hugh Calkins

II Ablation Program Planning 25

3 Equipment and Staffing 27

6 Electroanatomic Mapping Systems 83

Anshul M Patel, Vivek Y Reddy

7 Magnetic and Robotic Navigation 100

Bruce D Lindsay, Mitchell Faddis

8 Noncontact Mapping 118

Satoshi Higa, Yenn-Jiang Lin,Ching-Tai Tai, Shih-Ann Chen

vii

IV Ablation Procedures 135

9 Circumferential Ablation with PV Isolation Guided

by Lasso Catheter 137

Feifan Ouyang, Kazuhiro Satomi, Karl-Heinz Kuck

10 Circumferential Atrial Ablation 167

Carlo Pappone, Vincenzo Santinelli

11 Electrogram-Guided Ablation 184

Evan Lockwood, Koonlawee Nademanee

12 Linear Left Atrial Ablation 198

Mélèze Hocini, Kang-Teng Lim, Prashanthan Sanders, Pierre Jạs, Seiichiro Matsuo, Sébastien Knecht, Leonardo Arantès, Mark O’Neill, Yoshihide Takahashi,Jacques Clémenty, Michel Hạssaguerre

13 Tailored Approach to Ablation 210

Hakan Oral, Fred Morady

14 Ablation of Autonomic Ganglia 218

Hiroshi Nakagawa, Katsuaki Yokoyama, Benjamin Scherlag, Vikram Katari, Hiroshi Aoyama, Sara Foresti, Warren Jackman

15 Atrial Fibrillation Trigger Mapping 231

Francis Marchlinski, Fermin Garcia

V Ablation Strategies 249

16 A Comprehensive Overview of Ablation of Paroxysmal, Persistent, and Permanent Atrial Fibrillation: A Stepwise Approach 251

Pierre Jạs, Seiichiro Matsuo, Kang-Teng Lim, Mélèze Hocini, Sébastien Knecht, Leonardo Arantès, Pierre Bordachar, Jacques Clémenty, Michel Hạssaguerre

17 Emerging Technologies 260

Suneet Mittal, Jonathan Steinberg, Andrew Choi, Aysha Arshad

18 Identification and Elimination of Ancillary Arrhythmias 273

Paolo Ferrero, Pietro Francia, Riccardo Cappato

19 Ablation Procedure Follow-up and Definitions

of Success 281

Christopher Piorkowski, Gerd Hindricks, Hans Kottkamp

20 When and How to Re-Ablate 292

Michael Riley, David Callans

21 Postprocedural Care after Radiofrequency Catheter Ablation for Atrial Fibrillation 310

Alan Wimmer, Hakan Oral

C O N T R I B U T I N G A U T H O R S

Hiroshi Aoyama, MD, PhD

Research fellow Department of MedicineUniversity of Oklahoma Health Sciences CenterOklahoma City, Oklahoma

Aysha Arshad, MD

Assistant ProfessorDepartment of Cardiology

St Luke’s and Roosevelt HospitalsNew York, New York

Leonardo Arantès, MD

Assistant ProfessorDepartment of CardiologyGama Filho UniversityElectrophysiology AdvisorDepartment of CardiologyHôpital São José

Rio de Janeiro, Brazil

Conor D Barrett, MB, Bch, MRCPI

Clinical Fellow, Section of ElectrophysiologyDepartment of Cardiovascular MedicineCleveland Clinic

Cleveland Ohio

xi

Hugh Calkins, MD

Professor, of MedicineDepartment of MedicineJohns Hopkins University School of MedicineDirector of the Arrhythmia Service and Clinical EP LaboratoryJohns Hopkins Hospital

Baltimore, Maryland

David J Callans, MD

Professor Department of MedicineUniversity of PennsylvaniaAssociate Director, ElectrophysiologyHospital of the University of Pennsylvania Philadelphia, Pennsylvania

Riccardo Cappato, MD

DirectorCenter of Clinical Arrhythmia and ElectrophysiologyIRCCS Policlinico San Donato

Milan, Italy

Farooq A Chaudhry, MD, FACC, FASE

Associate Professor of MedicineDepartment of Medicine

Columbia University College of Physicians and Surgeons Director of Echocardiography; Associate Chief of CardiologyDepartment of Medicine

St Luke’s and Roosevelt HospitalsNew York, New York

Shih-Ann Chen, MD

Professor of MedicineDepartment of MedicineNational Yang-Ming UniversityDirector of Cardiac Electrophysiology LaboratoryDivision of Cardiology

Taipei Veterans General HospitalTaipei, Taiwan

Andrew Choi, BA

Research FellowDivision of Cardiology

St Luke’s and Roosevelt HospitalsNew York, New York

Jacques Clémenty, MD

ProfessorCardiology DepartmentUniversité Victor Segalen and Hôpital Cardiologique du Haut-Lévêque Bordeaux, France

Jennifer E Cummings, MD

Director of EP ResearchDepartment of Cardiovascular MedicineCleveland Clinic

Cleveland, Ohio

Isabel Deisenhofer, MD

Junior ProfessorDepartment of CardiologyTechnische University MünchenFellow

Department of CardiologyGerman Heart CenterMunich, Germany

Kenneth A Ellenbogen, MD

Kontos Professor of CardiologyDepartment of MedicineVirginia Commonwealth University/Medical College of VirginiaDirector, EP & Pacing Laboratory Medical College of VirginiaRichmond, Virginia

Mitchell N Faddis, MD, PhD

Associate Professor of MedicineInternal Medicine/Cardiovascular DiseasesWashington University School of MedicineCardiac Electrophysiologist

Internal Medicine/CardiologyBarnes Hospital

St Louis, Missouri

Paolo Ferrero, MD

Research and Clinical FellowCenter of Clinical Arrhythmia and ElectrophysiologyIRCCS Policlinico San Donato

Milan, Italy

Sara Foresti, MD

Research Fellow Department of MedicineUniversity of Oklahoma Health Sciences CenterOklahoma City, Oklahoma

Pietro Francia, MD

Research and Clinical FellowCenter of Clinical Arrhythmia and ElectrophysiologyIRCCS Policlinico San Donato

Milan, Italy

Fermin C Garcia, MD

Assistant Professor of Medicine Department of Medicine University of Pennsylvania Cardiac Electrophysiologist Department of MedicineHospital of the University of Pennsylvania Philadelphia, PA

David E Haines, MD

Corporate Chief of Cardiovascular Medicine and Medical Director

of the Heart Rhythm CenterDepartment of Internal MedicineWilliam Beaumont HospitalRoyal Oak, Michigan

Michel Hạssaguerre, MD

ProfessorDepartment of CardiologyUniversité Victor Segalen and Hơpital Cardiologique du Haut-LévêqueBordeaux, France

Satoshi Higa, MD, PhD

Assistant Professor of MedicineSecond Department of Internal MedicineUniversity of the Ryukyus School of MedicineDirector of Clinical Electrophysiology LaboratoryChief of Cardiology Division

Second Department of Internal MedicineUniversity of the Ryukyus HospitalOkinawa, Japan

Gerd Hindricks, MD, PhD

ProfessorHead of DepartmentDepartment of ElectrophysiologyHeart Center

University of LeipzigLeipzig, Germany

Mélèze Hocini, MD

Associate ProfessorCardiac Arrhythmias DepartmentUniversité Victor Segalen—Bordeaux 2Praticien Hospitalier

Cardiac Arrhythmias DepartmentHơspital Cardiologique du Haut LévèqueBordeaux, France

Jose F Huizar, MD

Assistant ProfessorDepartment of MedicineVirginia Commonwealth University/ Medical College of VirginiaDirector, Arrhythmic and Device Clinic

Department of MedicineHunter Holmes McGuire Virginia Medical CenterRichmond, Virginia

Warren M Jackman, MD

Professor of MedicineDepartment of Medicine University of Oklahoma Health Sciences CenterOklahoma City, Oklahoma

Pierre Jạs, MD

Professor Department of CardiologyUniversité Victor Segalen—Bordeaux 2 and Hơpital Cardiologique du Haut-LévèqueBordeaux, France

Karoly Kaszala, MD, PhD

Assistant ProfessorDepartment of MedicineVirginia Commonwealth University/Medical College of VirginiaDirector, Electrophysiology Laboratory

Department of MedicineHunter Holmes McGuire Virginia Medical CenterRichmond, Virginia

Jayanthi N Koneru, MD

FellowDepartment of CardiologyUniversity of Nebraska Medical CenterOmaha, Nebraska

Hans Kottkamp, MD, PhD

ProfessorDepartment of ElectrophysiologyHirslander Clinic

Head of DepartmentDepartment of ElectrophysiologyHeart Center

Zurich, Switzerland

Karl-Heinz Kuck, MD

Director of CardiologyDepartment of CardiologyAsklepios Klinik St GeorgHamburg, Germany

Kang-Teng Lim, MBBS

Cardiology DepartmentUniversité Victor Segalen and Hôpital Cardiologique du Haut-LévêqueBordeaux, France

Yenn-Jiang Lin, MD

Visiting StaffDivision of CardiologyTaipei Veterans General HospitalTaipei, Taiwan

Bruce D Lindsay, MD

Professor of MedicineDirector of Cardiac Electrophysiology Washington University School of Medicine

St Louis, Missouri

Evan E Lockwood, MD

Assistant ProfessorDepartment of MedicineUniversity of AlbertaCardiac ElectrophysiologistDivision of CardiologyMazankowski Alberta Heart InstituteEdmonton, Alberta, Canada

Kataneh Maleki, MD

Assistant ProfessorDivision of Cardiology

St Luke’s and Roosevelt HospitalsNew York, New York

Francis E Marchlinski, MD

Professor of MedicineDepartment of MedicineUniversity of PennsylvaniaDirector, Cardiac ElectrophysiologyDepartment of Medicine

Hospital of the University of PennsylvaniaPhiladelphia, Pennsylvania

Seiichiro Matsuo, MD

Cardiology DepartmentUniversité Victor Segalen and Hôpital Cardiologique du Haut-LévêqueBordeaux, France

Suneet Mittal, MD

Director, Electrophysiology Laboratory

St Luke’s and Roosevelt HospitalsNew York, New York

Hiroshi Nakagawa, MD, PhD

Professor of MedicineDepartment of MedicineUniversity of Oklahoma Health Sciences CenterOklahoma City, Oklahoma

Andrea Natale, MD

Consulting ProfessorDivision of CardiologyStanford UniversityPalo Alto, CaliforniaExecutive Medical DirectorTexas Cardiac Arrhythmia Institute

St David’s HospitalAustin, Texas

Mark D O’Neill, MB, BCH, DPhil

Department of Cardiology

St Mary’s HospitalLondon, England

Hakan Oral, MD

Associate ProfessorCardiovascular MedicineUniversity of MichiganDirector

Clinical Cardiac ElectrophysiologyUniversity of Michigan

Ann Arbor, Michigan

Feifan Ouyang, MD

Co-director EP LaboratoryDepartment of CardiologyAsklepios Klinik St GeorgHamburg, Germany

Carlo Pappone, MD, PhD

Director of ArrhythmologyArrhythmology DepartmentOspedale San Raffaele Milano, Italy

Anshul M Patel, MD

Clinical & Research FellowDepartment of MedicineHarvard Medical SchoolFellow in Cardiac ElectrophysiologyCardiac Arrhythmia Service

Massachusetts General HospitalBoston, Massachusetts

Christopher Piorkowski, MD

Doctor/ConsultantDepartment of ElectrophysiologyUniversity of Leipzig

Heart CenterLeipzig, Germany

Walid I Saliba, MD

Director of EP LaboratoriesDepartment of Cardiovascular MedicineCleveland Clinic

Cleveland, Ohio

Prashanthan Sanders, MBBS

Cardiology DepartmentRoyal Adelaide HospitalAdelaide, Australia

Vincenzo Santinelli, MD

Professor of CardiologyOspedale San RaffaeleScientific DirectorArrhythmologyOsepedale San RaffaeleMilan, Italy

Kazuhiro Satomi, MD, PhD

Co-Director, EP LaboratoryDepartment of CardiologyNational Cardiovascular CenterSuita, Japan

Benjamin J Scherlag, PhD

Professor of MedicineDepartment of MedicineUniversity of Oklahoma Health Sciences CenterOklahoma City, Oklahoma

Robert A Schweikert, MD

Director of OperationsDepartment of Cardiovascular MedicineCleveland Clinic

Cleveland, Ohio

David A Spragg, MD

Assistant ProfessorDepartment of MedicineJohns Hopkins University School of MedicineAssistant Professor

Division of CardiologyJohns Hopkins HospitalBaltimore, Maryland

Jonathan S Steinberg, MD

Professor of MedicineColumbia University College of Physicians & SurgeonsChief, Division of Cardiology

Endowed Director, Al-Sabah Arrhythmia Institute

St Luke’s and Roosevelt HospitalsNew York, New York

Director, ElectrophysiologyValley Hospital

Ridgewood, New Jersey

Ching-Tai Tai, MD

Professor of MedicineDepartment of MedicineNational Yang-Ming University School of MedicineVisiting Doctor

Division of CardiologyTaipei Veterans General HospitalTaipei, Taiwan

Yoshihide Takahashi, MD

Department of CardiologyAnjindai

Kanagawa, Japan

Oussama M Wazni, MD

Director of AF ResearchDepartment of Cardiovascular MedicineCleveland Clinic

Cleveland, Ohio

Alan Wimmer, MD

CardiologistElectrophysiologyDepartment of St, Luke’s HospitalMid America Heart InstituteKansas City, Missouri

Mark A Wood, MD

Professor of MedicineDepartment of Internal Medicine/CardiologyVirginia Commonwealth University Medical Center Richmond, Virginia

Katsuaki Yokoyama, MD, PhD

Research AssociateDepartment of MedicineUniversity of Oklahoma Health Sciences CenterOklahoma City, Oklahoma

This book is designed to provide a comprehensive and practical compendium onhow to establish programs and laboratories to treat atrial fibrillation; how to use com-plex imaging modalities and guidance systems; how to implement a variety ofcatheter-based ablation strategies, either isolated or in tandem; and how to monitorthe ablated patient’s course for complications and arrhythmia recurrence and managethese problems should they arise In short, we have attempted to deliver a practicalguide to all medical professionals who have an interest in catheter ablation of atrialfibrillation.

Hugh Calkins, MDPierre Jạs, MDJonathan S Steinberg, MD

PART

Introduction and Historical Perspective

This document summarizes the opinion of the task force members based on theirexperience and a review of the literature In addition, a draft of the document wasreviewed by other experts representing the participating organizations In writing a

“consensus” document, it was recognized that consensus does not mean that there wascomplete agreement among all task force members The writing group attempted toidentify those aspects of the field of catheter ablation of AF for which a true consensuscould be identified Anonymous surveys of the entire task force were used to identifythese areas of consensus, which are stated in Tables 1.1 and 1.2 of this chapter.The purpose of this chapter is to review and highlight those aspects of the Con-sensus Statement that are likely to have the largest impact on the management ofpatients undergoing or being considered for catheter ablation of AF Also reviewed

Indications for Atrial Fibrillation Ablation and Consensus

Recommendations

are several aspects of the Consensus Document that impact the reporting of comes as part of clinical trials on catheter ablation of AF.

out-Definitions and Indications for Catheter Ablation

Definitions

An initial topic covered in the Consensus Document are the definitions used to classifyvarious types of AF This is important because in the past a large number of terms were

AF Definition

• Paroxysmal AF is defined as recurrent AF (2 episodes) that terminates spontaneously within 7 days

• Persistent AF is defined as AF sustained beyond 7 days, or lasting less than 7 days but necessitating

pharmacologic or electrical cardioversion

• Longstanding persistent AF is defined as continuous AF of greater than 1 year duration.

as it refers to a group of patients where a decision has been made not to pursue restoration of sinusrhythm by any means, including catheter or surgical ablation

Indications for Catheter AF Ablation

• Symptomatic AF refractory or intolerant to at least one class I or class III antiarrhythmic medication

• In rare clinical situations, it may be appropriate to perform AF ablation as first line therapy

• Selected symptomatic patients with heart failure and/or reduced ejection fraction

• The presence of a left atrial thrombus is a contraindication to catheter ablation of AF

Indications for Surgical AF Ablation

• Symptomatic AF patients undergoing other cardiac surgery

• Selected asymptomatic AF patients undergoing cardiac surgery in whom the ablation can be performedwith minimal risk

• Stand-alone AF surgery should be considered for symptomatic AF patients who prefer a surgical approach,have failed one or more attempts at catheter ablation, or are not candidates for catheter ablation

Preprocedure Management

• Patients with persistent AF who are in AF at the time of ablation should have a TEE performed toscreen for thrombus

Technique and Lab Management

• Ablation strategies that target the PVs and/or PV antrum are the cornerstone for most AF ablation procedures

• If the PVs are targeted, complete electrical isolation should be the goal

• For surgical PV isolation, entrance and/or exit block should be demonstrated

• Careful identification of the PV ostia is mandatory to avoid ablation within the PVs

• If a focal trigger is identified outside a PV at the time of an AF ablation procedure, it should be targeted

• If patients with longstanding persistent AF are approached, ostial PV isolation alone may not be sufficient

• Heparin should be administered during AF ablation procedures to achieve and maintain an ACT of 300

to 400 sec

TABLE 1.1 Areas of Consensus: Definitions, Indications, Technique, and

Laboratory Management

used to describe types of AF, often with considerable overlap Also, numerous tencies had arisen between published studies The Consensus Document proposes that

inconsis-the following definitions of AF types be used in all future studies of AF ablation

Parox-ysmal AF is defined as recurrent AF (2 episodes) that terminates spontaneously within

seven days Persistent AF is defined as AF that is sustained beyond 7 days, or that lasts

Postprocedure Management

• Low molecular weight heparin or intravenous heparin should be used as a bridge to resumption ofsystemic anticoagulation following AF ablation

• Warfarin is recommended for all patients for at least 2 months following an AF ablation procedure

• Decisions regarding the use of warfarin more than 2 months following ablation should be based on thepatient’s risk factors for stroke and not on the presence or type of AF

• Discontinuation of warfarin therapy postablation is generally not recommended in patients who have a

• For research purposes, time to recurrence of AF following ablation is an acceptable endpoint after

AF ablation, but may underrepresent true benefit

• Freedom from AF at various points following ablation may be a better marker of true benefit andshould be considered as a secondary endpoint of ablation

• Atrial flutter and other atrial tachyarrhythmias should be considered treatment failures

• An episode of AF/flutter/tachycardia detected by monitoring should be considered a recurrence if ithas a duration of 30 seconds or more

• Single procedure success should be reported in all trials of catheter ablation of AF

• An AF/flutter/tachycardia episode is present if it is document by ECG and lasts at least 30 seconds

• All patients in a clinical trial should be followed for a minimum of 12 months

• Patients being evaluated as part of a clinical trial or in whom warfarin may be discontinued shouldhave some type of continuous ECG monitoring performed to screen for asymptomatic

less than 7 days but necessitates pharmacologic or electrical cardioversion Included

within the category of persistent AF is longstanding persistent AF, defined as continuous

AF of greater than 1 year duration The term permanent AF is defined as AF in which

cardioversion has either failed or not been attempted The task force felt that the term

permanent AF is not appropriate in the context of patients undergoing catheter and/or

surgical ablation of AF as it refers to a group of patients where a decision has been madenot to pursue restoration of sinus rhythm by any means, including catheter or surgical

ablation The task force also felt that the term chronic AF is vague and also should no

longer be used to describe populations of patients undergoing AF ablation

Indications for Catheter Ablation

The task force agreed that catheter ablation of AF in general should not be considered

as first line therapy The consensus among the task force was that the primary indicationfor catheter AF ablation is the presence of symptomatic AF refractory or intolerant to atleast one class I or class III antiarrhythmic medication The task force did recognize that

in rare clinical situations, it may be appropriate to perform catheter ablation of AF as firstline therapy Catheter ablation of AF was also considered appropriate in selected symp-tomatic patients with heart failure and/or reduced ejection fraction While some patientswith asymptomatic AF seek catheter ablation as an alternative to long-term anticoagula-tion, this desire by itself should not be considered an appropriate selection criterion.The presence of a left atrial thrombus was identified as a contraindication tocatheter ablation of AF Another contraindication to catheter ablation of AF is theinability to systemically anticoagulate a patient for at least the first 2 months follow-ing an ablation procedure

Techniques and Endpoints for Atrial Fibrillation Ablation

A variety of techniques have been developed for catheter ablation of AF These arereviewed in the Consensus Document The task force reached consensus on the fol-lowing recommendations concerning the techniques and endpoints of AF ablation:

1 Ablation strategies that target the pulmonary veins (PVs) and/or PV antrum arethe cornerstone for most AF ablation procedures

2 If the PVs are targeted, complete electrical isolation should be the goal

3 For surgical PV isolation, entrance and/or exit block should be demonstrated

4 Careful identification of the PV ostia is mandatory to avoid ablation within the PVs

5 If a focal trigger is identified outside a PV at the time of an AF ablation dure, it should be targeted if possible

proce-6 If additional linear lesions are applied, line completeness should be demonstrated

by mapping or pacing maneuvers

7 Ablation of the cavotricuspid isthmus is recommended only in patients with a tory of typical atrial flutter or inducible cavotricuspid isthmus–dependent atrialflutter

his-8 If patients with longstanding persistent AF are approached, ostial PV isolationalone may not be sufficient

Anticoagulation and Strategies to Prevent Thromboembolism

Careful attention to anticoagulation of patients before, during, and after ablation for

AF is critical to avoid the occurrence of a thromboembolic event, which is recognized

as one of the most serious complications of AF and also of AF ablation procedures.For this reason, the task force recommends that the anticoagulation guidelines pub-lished as part of the ACC/AHA/ESC 2006 Guidelines for the Management ofPatients with AF be adhered to (2) In particular, the guidelines for anticoagulation,both for long-term management and also those that apply to cardioversion proce-dures, should be followed In addition to following these anticoagulation guidelines,there was a consensus among the task force members that patients with persistent AFwho are in AF at the time of ablation should have a TEE performed to screen for athrombus The lower level of anticoagulation during an ablation procedure should bemaintained at an ACT of at least 300 to 350 seconds throughout the procedure.After catheter ablation and sheath removal, anticoagulation should be reinitiatedpromptly There was a consensus among the task force members that:

1 Warfarin is recommended for all patients for at least 2 months following an AFablation procedure

2 Decisions regarding the use of warfarin more than 2 months following ablationshould be based on the patient’s risk factors for stroke and not on the presence ortype of AF

3 Discontinuation of warfarin therapy postablation is generally not recommended in

Despite these rather stringent recommendations, it is recognized that many patientsare highly motivated to discontinue warfarin As with all decisions concerning apatient’s care, the cardiologist and patient need to discuss in detail the risks and ben-efits of discontinuing warfarin Patients with two or more CHADS risk factors need

to be informed that if they elect to discontinue warfarin they are accepting a risk ofstroke Furthermore, they need to be informed that no studies to date have shownthat elimination of AF with catheter ablation of AF reduces a patient’s short- or long-term risk of stroke

Training Requirements and Competencies

The training and competencies required for training in AF ablation differ from otherablation procedures because, in comparison, ablation of AF is more difficult, is asso-ciated with greater risks, and requires more careful follow-up The American College

of Cardiology/American Heart Association 2006 update of the clinical competencestatement on invasive electrophysiology studies, catheter ablation, and cardioversionproposes a minimum of 30 to 50 AF ablation procedures for those who undergo fel-lowships in clinical cardiac electrophysiology (3) The task force felt that this numberunderestimates the experience required for a high degree of proficiency Trainees whointend to perform ablation of AF independently should consider additional trainingafter the standard fellowship is completed

Electrophysiologists who have already completed a fellowship and choose toundergo training for ablation of AF should observe colleagues with a high degree ofexpertise and a period of supervision is advisable The task force felt that it was appro-priate for experienced electrophysiologists to be supervised when they begin to per-form these procedures Furthermore, the task force felt that electrophysiologistsshould perform several ablation procedures for AF per month if they intend to remainactive in this area

Follow-up and Monitoring Guidelines

Arrhythmia monitoring is an important component of the initial evaluation ofpatients who are to undergo catheter ablation procedures for AF ECG monitoringalso plays an important role in the follow-up after an ablation procedure Early recur-rences of AF are common during the first 1 to 3 months following a catheter abla-tion procedure For this reason, arrhythmia monitoring to assess the efficacy ofcatheter ablation is typically delayed for at least 3 months following catheter ablation.Arrhythmia monitoring may be in the form of intermittent sampling using a standardECG or a patient activated event monitor with or without a memory loop Varioustypes of continuous monitoring systems are also available

There was general agreement among the task force members that all patients whoundergo catheter ablation of AF should be seen in follow-up at a minimum of 3months following the ablation procedure and then every 6 months for at least 2 years.ECGs should be obtained at all follow-up visits and patients who complain of palpi-tations should be evaluated with an event monitor Prior to hospital discharge, it isrecommended that patients receive detailed follow-up instructions and be providedwith contact information that will facilitate prompt evaluation of symptoms consis-tent with a late complication of the ablation procedure Although there was no con-sensus among the task force members on the role of routine imaging studies to screenfor pulmonary vein stenosis, there was general agreement that the threshold for usingimaging tools for symptom evaluation should be low

Although early recurrence of AF carries an independent risk of treatment failure,its occurrence should not prompt immediate re-ablation attempts, as 20% to 57% ofpatients experiencing this event within the first months postablation will not have anyfurther arrhythmias during long-term follow-up Since the mechanism of AF postab-lation may be different from that of the patient’s clinical arrhythmia and may resolvecompletely upon resolution of the inflammatory process, the Consensus Documentnotes that some operators choose to treat all patients with suppressive antiarrhythmicagents for the first 1 to 3 months following ablation Repeat ablation proceduresshould be delayed for at least 3 months following the initial procedure if the patient’ssymptoms can be controlled with medical therapy

Outcomes and Efficacy of Catheter Ablation

Until the publication of the Consensus Document, there had been no tion in the design of clinical trials of AF ablation It is now well recognized that theoutcomes of AF ablation differ considerably depending on whether patients haveparoxysmal, persistent, or longstanding persistent AF Similarly, variables such as age,concomitant cardiac disease, and left atrial size are important determinants of out-come Other important considerations are the duration of the blanking period, thefrequency and intensity of arrhythmia monitoring, whether patients with atrial flutterduring follow-up are classified as successes or failures, the use of AADs, and the fre-quency and timing of performance of repeat ablation procedures Each of these fac-tors plays a role in how a particular study defines “success.”

standardiza-In preparing the Consensus Document, the writing group reviewed the results ofnearly two dozen nonrandomized trials of catheter ablation of AF that included atleast 50 patients The reported single procedure efficacy of catheter ablation in these

trials varied widely Although the single procedure success of catheter ablation ofpatients with paroxysmal AF ranged from 38% to 78%, most series reported a singleprocedure efficacy of 60% or greater In contrast, the single procedure success ofcatheter ablation of patients with persistent AF ranged from 22% to 45%, with mostcenters reporting an efficacy of 30% or less The single procedure success of catheterablation of patients with mixed types of AF ranged from 16% to 84% The reportedmultiple procedure success of catheter ablation of patients with paroxysmal AFranged from 54% to 80%, with most series reporting a multiple procedure efficacy of70% or greater The multiple procedure success of catheter ablation of patients withpersistent AF ranged from 37% to 88%, with most centers reporting a multiple pro-cedure efficacy of 50% or greater The multiple procedure success of catheter ablation

of patients with mixed types of AF ranged from 30% to 81%

The Consensus Document also reviews the findings of five randomized studies of AFablation, as well as the findings of a large international survey of catheter ablation of AF(4).The results of the reviewed studies and survey provide substantial evidence of the effi-cacy of catheter ablation for treatment of patients with AF However, it was also clear tothe writing group that outcomes vary considerably Potential factors identified by thewriting group that may impact outcome include: (a) differences in technique, (b) differ-ences in follow-up and definitions of success, (c) differences in the use of antiarrhythmictherapy, and (d) differences in experience and technical proficiency, and so forth

Surgical Ablation of Atrial Fibrillation

The task force reached the following areas of consensus concerning the indicationsfor surgical AF ablation: (a) symptomatic AF patients undergoing other cardiac sur-gery, and (b) selected asymptomatic AF patients undergoing cardiac surgery in whichthe ablation can be performed with minimal risk Stand-alone AF surgery should beconsidered for symptomatic AF patients who prefer a surgical approach, have failedone or more attempts at catheter ablation, or are not candidates for catheter ablation

Clinical Trial Considerations

The many unresolved questions and issues regarding currently available clinical trialdata provide a strong incentive for conducting additional clinical studies of specificdesign to answer critical questions in the ablative arena These include: (a) sufficientlypowered, randomized mortality studies; (b) multicenter outcome trials; (c) industry-sponsored device approval studies; and (d) carefully constructed single and multicen-ter registry studies

Standards for Reporting Outcomes in Clinical Trials

In light of this need, the task force defined 18 specific standards for reporting comes in clinical trials of catheter ablation for AF, including the following for whichthere was consensus:

out-1 A blanking period of 3 months should be employed after ablation when ing outcomes

report-2 Freedom from AF/flutter/tachycardia off antiarrhythmic therapy is the primaryendpoint of AF ablation

3 For research purposes, time to recurrence of AF following ablation is an able endpoint after AF ablation, but may underrepresent true benefit.

accept-4 Freedom from AF at various points following ablation may be a better marker oftrue benefit and should be considered as a secondary endpoint of ablation

5 Atrial flutter and other atrial tachyarrhythmias should be considered treatmentfailures

6 An episode of AF/flutter/tachycardia detected by monitoring should be sidered a recurrence if it has a duration of 30 seconds or more

con-7 An AF/flutter/tachycardia episode is present if it is documented by ECG andlasts at least 30 seconds

8 Single procedure success should be reported in all trials of catheter ablation of AF

9 An event monitor should be obtained to screen for recurrent cardia in patients who complain of palpitations during follow-up

AF/flutter/tachy-10 Patients being evaluated as part of a clinical trial or in whom warfarin may be continued should have some type of continuous ECG monitoring performed toscreen for asymptomatic AF/flutter/tachycardia

dis-11 24-hour Holter monitoring is an acceptable minimal monitoring strategy forpatients enrolled in a clinical trial and is recommended at 3- to 6-month inter-vals for 1 to 2 years following ablation

1 Calkins H, Brugada J, Packer DL, et al HRS/EHRA/ECAS expert consensus statement

on catheter and surgical ablation of atrial fibrillation: recommendations for personnel, icy, procedures and follow-up A report of the Heart Rhythm Society (HRS) Task Force on

pol-catheter and surgical ablation of atrial fibrillation Heart Rhythm 2007;4(6):816–861

2 Fuster V, Ryden LE, Cannom DS, et al ACC/AHA/ESC 2006 guidelines for the ment of patients with atrial fibrillation—a report of the American College of Cardiology/ American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (writing committee to revise the 2001 guide-

manage-lines for the management of patients with atrial fibrillation) J Am Coll Cardiol 2006;48(4):

149–246.

3 Tracy CM, Akhtar M, DiMarco JP, et al American College of Cardiology/American Heart Association 2006 update of the clinical competence statement on invasive electrophysiology studies, catheter ablation, and cardioversion: a report of the American College of Cardiology/ American Heart Association/American College of Physicians Task Force on Clinical Com-

petence and Training developed in collaboration with the Heart Rhythm Society J Am Coll

Cardiol 2006;48(7):1503–1517.

4 Cappato R, Calkins H, Chen SA, et al Worldwide survey on the methods, efficacy, and safety

of catheter ablation for human atrial fibrillation Circulation 2005;111(9):1100–1105.

—William Harvey, Exercitatio Anatomica De Motu Cordis et Sanguinis in

Animalibus, 1628

Atrial fibrillation (AF) is the most common sustained tachyarrhythmia encountered

by physicians The prevalence of AF in patients over the age of 65 is approximately6%, and approaches 10% in patients over the age of 85 (1) As the median age of thepopulation in the United States becomes older, the epidemiologic burden of AF inthis country will likely increase Currently approximately 2.2 million people in theUnited States have AF (1) AF, although typically not a life-threatening arrhythmiaper se, is associated with increased risk of stroke (2), heart failure, and increased mor-tality The stroke risk in patients with AF, for instance, is increased between five- andsevenfold compared to similar patients without AF (3,4)

Therapy for AF can be divided into two major paradigms—rate control andrhythm control Rate control, as the name implies, focuses exclusively on preventing

an uncontrolled, rapid ventricular response rate in the setting of AF Strategies toachieve rate control typically include either pharmacological agents to slow conduc-tion through the atrioventricular (AV) node (i.e., beta-blockers or calcium-channelblockers), or ablation of the AV junction and implantation of a permanent pacemaker.Large prospective randomized trials have validated rate control as a reasonable option

Nonpharmacological Therapy for Atrial

Fibrillation: An Historical Overview

Hugh Calkins

in patients with AF, particularly in terms of overall mortality (5,6) However, such astrategy does nothing to reduce the stroke risk and loss of AV synchrony seen inpatients with AF, and as such, represents a suboptimal strategy in many patients.The second paradigm, rhythm control, has historically involved the use of antiar-rhythmic medications and/or DC cardioversion from AF into sinus rhythm Antiar-rhythmic medications used for the maintenance of sinus rhythm include class I andclass III agents Randomized prospective data have demonstrated that amiodarone,compared to other class III and to class I medications, is the most effective antiar-rhythmic drug to prevent AF (7,8) Long-term therapy with amiodarone is imperfect,however, due both to limited efficacy and to attendant end-organ toxicities Recur-rence rates in patients treated with amiodarone are approximately 35% (7) As impor-tant, amiodarone has dose-dependent effects on thyroid, liver, and pulmonary func-tion In patients treated with DC cardioversion alone (i.e., without the suppressiveeffects of antiarrhythmic medications) AF recurrence is predictably high, with nearly66% of cardioverted patients developing recurrent AF within 15 months (9) In partbecause of the limitations of effective and safe pharmacological therapy for AF sup-pression, clinicians have sought nonpharmacological interventions to achieve rhythmcontrol Two major modalities—surgical intervention and catheter-based interven-tion for the treatment of AF—have developed over the past 25 years The currentchapter reviews these two modalities, with a particular emphasis on the historical evo-lution behind each, and on the seminal discoveries made during that evolution thatinform our current practices in 2007.

Surgical Treatment for Atrial Fibrillation

In 1959, Moe hypothesized that AF was due to multiple randomly propagating trant waves in the atrium, suggesting that functional reentry was the mechanismunderlying fibrillation (10–12) In subsequent work by Allessie et al (13–15), Moe’shypothesis was confirmed AF was demonstrated to require at least six to eight cir-culating reentrant wavefronts Maintenance of AF depended both on a critical atrialmass and on conduction velocity and refractory periods in the atrial tissue to supportfunctional reentry

reen-Twenty years after Moe’s hypothesis, James Cox et al began a series of tionary clinical experiments to cure AF surgically (16–19) Initial surgical interven-tions focused on electrical isolation of the left atrium (20) Although this procedureresulted in AV synchrony and controlled ventricular response rates, patients still were

revolu-at risk of revolu-atrial thrombosis and embolism, due to ongoing fibrillrevolu-ation in the isolrevolu-atedatrium In the mid-1980s, Cox et al developed a surgical procedure designed toeliminate AF rather than isolate it—the MAZE procedure It was based on a series ofincisions in the left and right atria that would facilitate sinus node to AV junction con-duction while at the same time preventing propagation of fibrillatory wave fronts.The initial MAZE-I procedure resulted in unacceptable high rates of chronotropicincompetence, and was modified to the MAZE-II procedure Because the MAZE-IIprocedure was technically difficult to perform, even for its inventors, it was furthermodified into the MAZE-III procedure (21) The MAZE-III involved a complex set

of incisions in both the left and right atria These incisions included circumferentiallesions around the left- and right-sided pulmonary veins (PVs), lesions from the leftsuperior PV (LSPV) to the mitral valve (MV) annulus, left atrial appendage removal,and a series of lesions in the right atrium (19,21)

The MAZE-III procedure has become the standard by which other surgicalinterventions for AF have been judged Short-, intermediate-, and long-term data areavailable from Cox et al for patients undergoing the MAZE-III (22–24), both forlone AF and in conjunction with other cardiovascular procedures (24) In the 5 yearsbetween 1987 and 1992, 47 patients underwent either the MAZE-I or MAZE-IIprocedure From then until 2000, Cox et al have performed 308 MAZE-III proce-dures Operative mortality for this group was 2.9%, with short-term AF or atrial flut-ter (AFL) recurrence rates of 37% (20) These high recurrence rates, however, werenot indicative of long-term procedure failure Rather, they likely represent atrial irri-tation and changes in atrial electrophysiological properties unique to the postopera-tive period In a review of 8.5 years of follow-up, Cox et al reported a 98% successrate, defined as freedom from any AF (23) Half of the treatment failures by surgeryalone were successfully treated with antiarrhythmic drugs, for an overall cure rate of99% The stroke rate in this population, anticoagulated for the initial postoperativeperiod but then off of systemic anticoagulant therapy, was 0.7% A recent report onthe 15-year follow-up of these patients shows that the results continue to be durable,

Despite the high success rates and strikingly low stroke rates in patients going the MAZE-III, widespread adoption of the procedure has been limited In partthis has been due to concerns about perioperative sequelae including the need forpermanent pacemaker implantation and the loss of atrial mechanical function Cox

under-et al have reported that up to 15% of patients undergoing the MAZE-III have sequently had pacemakers implanted postoperatively Most of these patients, how-ever, had antecedent sinus node dysfunction that became clinically apparent after ces-sation of AF, rather than acute injury to the AV conduction system during surgery

preservation of biatrial transport function The technically challenging nature of thesurgery, rather than lack of efficacy or attendant complications, appears to be theprincipal factor limiting widespread adoption of the full MAZE-III procedure In

1996, Cox et al developed a minimally invasive version of the MAZE (25) This cedure, in which cryoablation is used to form the atrial lesion set through a limitedthoracotomy, has yielded promising short-term results, but does not yet have thelong-term follow-up of the MAZE-III procedure

pro-Other surgical interventions for AF have been developed (20,26,27) Someare of purely historical interest In 1985, Guiraudon described a unique surgicaltreatment of atrial fibrillation, in which a corridor of intact atrial tissue connectingthe sinus node and the AV junction was isolated (20) Although this procedureallowed for ventricular rate control by the sinus node, it necessarily left the bulk

of atrial tissue in fibrillation As such, the corridor procedure did nothing toreduce thromboembolic risk or atrial mechanical dysfunction due to AF, and wasultimately abandoned

Non-MAZE surgical approaches are also currently in practice Gillinov et al atthe Cleveland Clinic have presented results from a series of 513 patients undergoingsurgical ablation of AF using an epicardial radiofrequency (RF) ablation system(Atricure Inc, West Chester, OH) (28) In this series, patients with preoperative AFpresenting for cardiac surgery underwent concomitant PV isolation and LAappendage removal Most patients were referred for valvular surgery Although theperioperative AF incidence was 57%, 84% of patients were free of AF after 1 year Nostrokes were observed during long-term follow-up, and 4% of patients requiredpacemaker implantation

The number of randomized clinical trials investigating the efficacy of MAZE-III

or maze-related procedures is limited Reston et al identified four such trials, inwhich MV surgery in conjunction with AF ablative lesion application was compared

to MV surgery alone (29) They found that restoration of sinus rhythm (81% vs 17%)and prevention of subsequent stroke (0% vs 5.8%) were strongly favored by MAZE-III or maze-related surgery These procedures had no significant impact on overallmortality Pacemaker implantation was higher in patients undergoing AF surgicalintervention than in patients undergoing MV surgery alone (3.9% v 1.5%)

In summary, there has been a 25-year history of surgical intervention for AF Thegold standard for this procedure has been the Cox MAZE-III procedure This inter-vention has demonstrated the virtual elimination of both AF recurrence and long-term stroke incidence The morbidities associated with cardiac surgery, however, andthe complexity of the lesion set has led both surgeons and interventional cardiologists

to investigate other nonpharmacological interventions that approach the treatmentresults of the MAZE-III Catheter-based attempts to recreate the MAZE-III lesionset have evolved over the last 15 years, and form the basis of current endovascularprocedures to treat AF The evolution of these procedures is discussed below

Catheter-Based Treatment for Atrial Fibrillation

Catheter ablation for atrial tachyarrhythmias is a relatively recent phenomenon(30–35) The propagation of electrical activation from atria to ventricles over myocar-dial fibers was originally described in 1883 (36) Nearly a century later, Scheinman et

al described the first catheter-based ablation procedure—His bundle interruption forthe control of ventricular response rates to refractory supraventricular tachycardias(37) Over the last 25 years, catheter ablation techniques have become standard, cur-ative therapy for AVNRT (32), accessory pathway ablation (33,35), and ablation ofmacroreentrant atrial flutter (34) Although ablation of the AV junction has longbeen accepted as a palliative treatment for AF, curative catheter-based therapy hasevolved rapidly since the early 1990s Initial work focused on linear and MAZE-likelesions sets in the right (38,39), right and left (40), and left atria (41) More recently,the importance of AF triggers (particularly those located in the PVs) has been recog-nized and targeted (42)

Linear Ablation Strategies for Treating Atrial Fibrillation

Initial ablation attempts to cure atrial fibrillation focused on linear lesions confined tothe right atrium Between 1994 and 1996, Haissaguerre et al investigated the effects

of linear lesion sets in patients with symptomatic, drug-refractory AF (40) Forty-fiveinitial patients were studied and followed over the long term Patients initially under-went right atrial ablation only, with either a single ablation line from SVC to IVC overthe atrial septum, or multiple lines (longitudinal and transverse) to compartmentalizethe right atrium The procedure led to stable sinus rhythm in 18 of 45 patients (40%)during the procedure Sustained AF was inducible in 40 of 45 patients, however, and

19 patients underwent repeat ablation of left- or right-sided atrial flutter or focal atrial

AF off antiarrhythmic drugs, with another nine patients free of AF on a previously fective medication (overall success of 33%) Nine of 45 patients had significant improve-ment of their symptom burden with the aid of an antiarrhythmic medication, whereasthe remaining 21 of 45 patients had no appreciable effect from RA-only ablation After

with seven previous responders (either cure or significant reduction in AF burden)reverting to frequent AF Successful results with RA-only lesions were seen in only 17

of 45 patients

Other investigators have prospectively attempted curative lesion sets confined tothe right atrium Natale et al studied 18 patients with symptomatic, drug-refractory AF(43) Although the lesion sets varied somewhat among the patients (seven with twointercaval lesions, ablation of the cavotricuspid isthmus, and an anterior RA line; 11with a single intercaval line, a septal line, and cavotricuspid isthmus ablation), the results

patients remained free from atrial arrhythmia recurrence Most of the 13 recurrencesoccurred within 2 months of the procedure The particular lesion set did not predictprocedure efficacy Thus, although linear ablation confined to the right atrium to cure

AF is attractive from a technical and safety standpoint, multiple trials with intermediateand long-term follow-up have shown it to be a largely ineffective procedure (39,44).Recognizing the limited efficacy of RA-only ablation for AF, several groupsbegan prospective investigations of biatrial and left-atrial linear ablation Haissaguerre

et al performed left atrial ablation in 10 of their 45 patients described above (40).Linear ablation in this group terminated AF during the procedure in eight of 10patients In five of 10 patients, sustained AF could not be induced after the proce-dure Intermediate follow-up demonstrated success in six of 10 patients (with twopatients requiring ongoing antiarrhythmic medications)

Between 1996 and 1998, the same group systematically studied biatrial linearablation to cure AF (41) Forty-four patients were enrolled prospectively, the major-

had persistent AF All patients underwent a similar ablative procedure In the rightatrium, an intercaval septal line and ablation of the cavotricuspid isthmus were made

In the left atrium, linear lesions were applied from the superior PVs to the posterior

MV annulus, including the inferior PV ostia A roof line connecting the two superiorPVs was performed in all patients; a septal left-sided line from the right superior PV

to the fossa ovalis was performed in 23 of 44 patients

This complex lesion set was technically difficult, requiring multiple procedures

significantly improved, and seven were without improvement Success rates increased

to 37 of 44 patients with the use of antiarrhythmic medications However, there wereclearly important caveats to the study Only seven of the patients were treated with asingle procedure, whereas the rest were treated with multiple procedures for AF recur-rence, ablation of AF triggers, and/or the ablation of iatrogenic left atrial flutters Per-haps most importantly, triggers of AF arising from the PVs were identified and ablated

in 26 of the 44 patients studied Given the clear importance of trigger elimination incatheter-based cures of AF (discussed below), these results undoubtedly confounded

an analysis of left atrial linear lesions alone as a curative approach to AF Indeed, tion of triggering foci and the creation of at least one successful line of block were thetwo sole predictors of success in the 37 patients with a favorable outcome

abla-Other linear left atrial lesion sets have been investigated Swartz et al pursued acatheter-based recreation of the Cox MAZE lesion set; technical difficulty and com-plication rates limited the widespread application of the procedure, however (20) Amuch simpler left atrial lesion pattern was investigated prospectively by Pappone

et al (45) Twenty-seven patients with highly symptomatic, drug-refractory, ysmal AF underwent biatrial lesion application using a novel (at the time) mappingsystem Fourteen patients underwent biatrial ablation, with three linear lesions in the

parox-RA (posterior intercaval, cavotricuspid isthmus, septal) and a single, long linear lesionsurrounding the PV ostia and connecting to the MV annulus in the left atrium Theleft atrial lesion alone was performed in isolation in five patients, wheras the RA lesionset alone was performed in eight patients The success and complication ratesreported by Pappone et al were relatively good, with 16 of 27 patients entirelyasymptomatic from AF (four on antiarrhythmic medications), and another four withmarkedly reduced symptoms No acute complications were reported Successappeared to be predicted by biatrial ablation (85% success vs 50%–60% with single-chamber ablation).

In part because of the limited efficacy of linear ablation alone for AF, and in partbecause of critically important observations by Haisaguerre et al of the triggerednature of AF (discussed below), linear ablation alone for AF is currently not widelyperformed However, observation made by the groups that pursued linear ablation—unmasked triggering foci in patients undergoing linear ablation, and the development

of simple lesion sets around the PV ostia, in particular—continue to inform currentcatheter-based ablation strategies for AF

Pulmonary Vein–Targeted Ablation Strategies for Atrial Fibrillation

A seminal event in the catheter-based treatment of AF was the observation by saguerre et al that fibrillation could be triggered by rapidly firing ectopic atrial foci(42,46,47) In a series of publications in the mid- and late 1990s, Haissaguerre’sgroup reported the successful ablation of AF through radiofrequency ablation offocal trigger points In 1994, they described three patients with atrial tachyarrhyth-mias (46) In the first patient, a focal, rapidly firing atrial tachycardia mimicked AF

Hais-on ECG, and was successfully ablated The secHais-ond patient had AT-induced AF, againwith successful ablative therapy targeting the ectopic trigger In the final patient ofthe series, a focal right atrial septal trigger was found and ablated, with markeddiminution of AF burden These initial results were expanded on by a larger series

atrial foci (47) In three patients, these foci were located in the RA; in the other six

months of follow-up, there were no observed recurrences of AT or AF

In a larger, landmark study of 45 patients with symptomatic, drug-refractoryparoxysmal AF, Haissaguerre et al reported that all 45 had demonstrable focal atrial

as four triggering sites were observed A total of 69 triggering foci were found, themajority of which (31/69) were located in the left superior PV (LSPV) Other fre-quent sites included the right superior PV (RSPV; 17/69), left inferior PV (LIPV;11/69), and right inferior PV (RIPV; 6/69) Three ectopic foci were located in the

RA AF induction was spontaneously observed in 36 patients, and was characterized

by short bursts of two or more repetitive focal firings (40/45 patients) Ablation ofectopic foci was successfully achieved in 38/45 patients Short-term recurrence of AF

remained free of AF (62%), without the use of antiarrhythmic medications; 17patients, including the early failures, had recurrence of AF

The observation that AF is frequently triggered by ectopic, rapidly firing atrialfoci amounted to a paradigm shift in ablative treatment Surgical and catheter-basedstrategies to date had focused principally on substrate modification, in an effort todisrupt the maintenance of AF Many of these strategies involved surgical or ablative