Ablation For Atrial Fibrillation. Bill Petrellis Electrophysiologist

Transcription

1 Ablation For Atrial Fibrillation Bill Petrellis Electrophysiologist

2 AF is the most common arrhythmia in the Western world Prevalence 1.1% in Australia conservative estimate - 240,000 June 2009 AF is an independent risk factor for mortality

3 Cause of significant morbidity stroke and heart failure, medication side effects Significant contributor to health care expenditure Recurrent hospitalisation and ED presentations

4 Management of Atrial Fibrillation Goals of AF management Treat symptoms Rate control vs rhythm control decide early Prevent complications Stroke - anticoagulation Heart failure / cardiomyopathy rate/rhythm

5 Management of Atrial Fibrillation Rhythm control anti-arrhythmic drugs (AAD) Limited Options Sotalol Flecainide Amiodarone

6 Management of Atrial Fibrillation Limited Efficacy AFFIRM trial of rhythm versus rate control in AF Substudy maintenance of SR Amiodarone ~ 60% Class I agents (flecainide) 23% Sotalol 38% Rate control arm: 34% spontaneously in SR

7 Catheter Ablation Catheter ablation has revolutionised the management of patients with tachyarrhythmias Has evolved from the combination of electrophysiologic studies and arrhythmia surgery In 1968 epicardial mapping could identify the site of an accessory pathway and surgical interruption could cure WPW syndrome Maze procedure devised to achieve surgical cure of atrial fibrillation

8 Catheter Ablation Radiofrequency (RF) - low voltage, high frequency electrical energy Delivered from the tip of a catheter to the endocardial surface to produce controlled focal tissue ablation Used since early 1990 s for effective cure of SVT usually a focal target for ablation Cure in 95% with ~ 1% complication rate

9 AF Ablation Success rates for atrial fibrillation ablation are much lower Paroxysmal AF ~ 70-80% Persistent AF ~ 50-60% Permanent AF ~ 30% 30-50% of patients require a subsequent procedure higher if persistent / permanent

10 AF Ablation How is atrial fibrillation different? AF not a focal arrhythmia but rather a disease of triggers and substrate not a single target Requires more extensive ablation resulting in longer procedure time, higher complications and inherent lower efficacy

11 AF Ablation AF ablation predominantly targets the left atrium GOALS Eliminate triggers for AF initiation = Pulmonary Vein Isolation the cornerstone of every AF ablation? Only requirement for paroxysmal AF Eliminate tissue that perpetuates AF = Substrate modification or left atrial ablation Essential for persistent / permanent AF (+ PVI)

12 Ablation Targets PV Triggers Left atrium Substrate TRIGGER Muscular sleeves of the PV s Irregular rapid bursts May be enough to cause A Fib SUBSTRATE Atrial disease that allows maintenance of A Fib

13 Management of Atrial Fibrillation Ablation has emerged as an alternative treatment strategy offering the possibility of effective management and potentially cure The AF ablation procedure has evolved over the past decade and is getting better with new tools and technologies Better understanding the mechanisms of AF have been fundamental to developing effective ablation strategies

14 Paroxysmal AF Ablation Triggered AF

15 Mechanisms of AF Haissaguerre 1998 Bordeaux : Studied patients with paroxysmal atrial fibrillation Hypothesis Pulmonary veins = triggers of atrial fibrillation and may be focal targets for ablation

16 Mechanisms of AF Haissaguerre M et al. NEJM 1998;339:659-66

17 Mechanisms of AF Triggers Atrial Fibrillation High frequency firing in the PV gave rise to AF initiation Haissaguerre M et al. NEJM 1998;339:659-66

18 Conclusions Benign isolated pulmonary vein ectopic beats were transformed into a dangerous burst of atrial discharges - initiators of AF Due to automaticity of muscular sleeves which extend from the left atrium to the pulmonary venous wall Respond to ablation

19 Focal AF Ablation Initial attempts at focal ablation within the pulmonary veins was limited by: long procedure times waiting for PV ectopy Presence of multiple foci high recurrence rates High rate of PV stenosis (up to 42%) Gave rise to the concept of pulmonary vein isolation => Segmental Ostial Catheter Ablation SOCA

20 LAO Projection

21 Segmental Ostial Catheter Ablation Focal RF lesions applied at the pulmonary vein ostium Designed the Lasso catheter to record electrical signals at the PV ostium RF ablation delivered at sites of early signals Confirm electrical isolation using a Lasso (absence of pulmonary vein signals) Entry / exit block using pacing techniques Aim to isolate all four pulmonary veins PV

22 Pulmonary Vein Isolation (PVI) Segmental Ostial Catheter Ablation (SOCA)

23 CARTO 3D Navigation Passive magnetic field sensor at catheter tip External ultra low magnetic field emitter (locator pad) Processing unit Gepstein L et al. Circ 1997;95: (Haifa Israel)

24 CARTO 3D Navigation Accurate determination of catheter location and orientation - navigation Non fluoroscopic reduces radiation exposure to patient and operator Allows creation of 3D geometry of the cardiac chamber in real time atrial shell Electrophysiological information colour coded and superimposed on the 3D shell voltage, activation

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26 Evolution of AF Ablation Pappone 2000 Milan Mimic surgical incisions using continuous linear lesions created by RF ablation around the pulmonary vein antrum (within atrium not vein) Concept of Left Atrial Catheter Ablation LACA Anatomical ablation - no lasso catheter to confirm PV isolation

27 Circumferential LA Ablation Pappone C et al. Circ 2000;102:

28 Ann Arbor 80 pts with Paroxysmal AF: 40 SOCA 40 LA Circumferential Ablation (LACA) Freedom of symptomatic AF at 6 months: 67% SOCA 88% LACA Oral H & Morady F et al. Circ 2003;108:

29 Conclusions Encircling lesions eliminate PV triggers May also: Eliminate rotors or mother waves Ablation of other potential triggers (e.g. Ligament of Marshall) 20-30% of LA is excluded limiting area for circulating wavelets critical mass?

30 If the triggers for paroxysmal atrial fibrillation have been eliminated why is there 20-30% recurrence of AF? Reconnection of the pulmonary veins Non pulmonary vein triggers

31 85 non-pv foci in 36 pts Ostia of PVs including between ipsilateral veins (39) Posterior LA wall (30) Other LA site (5), RA (5), CS (4), SVC (2) 84 pt single ablation 76 pt repeat ablation (recurrence) Haissaguerre M et al. PACE 2003;26:

32 Persistent / Permanent AF Diseased Substrate

33 Diminishing return of left atrial ablation for persistent or permanent atrial fibrillation AF begets AF Left atrial remodelling substrate LA dilatation and fibrosis Dispersion of refractoriness, zones of slow conduction, re-entry, pivot points, rotors

34 A New Perspective Nademanee 2004 Complex Fractionated Atrial Electrograms - CFAE s Areas of slow conduction Pivot points of wavelets CARTO to identify sites in the left and right atrium Nadamanee K et al. JACC 2004;43:

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36 CFAE s - Constant Distribution Interatrial Septum Pulmonary Veins Roof Of Left Atrium Left Posteroseptal Mitral Annulus Coronary Sinus Ostium

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38 Ablation of these areas stop wavelet reentry and prevent perpetuation of AF Aim to modify / eliminate the substrate rather than the triggers of AF

39 Persistent / Permanent AF In practice what do we ablate? Pulmonary vein isolation LACA (always) Additional lines roof line, between veins,?mitral isthmus line CFAE ablation Trigger abolition and substrate modification Tailor of ablation approach for the individual

40 Substrate Modification Encircling lines around and between PVs Roof line ± Mitral isthmus line (flutter)

41 Technology Update If AF is not a focal arrhythmia, why are we still using the same tool historically used to treat focal arrhythmias? Need to create a circumferential lesions for pulmonary vein isolation why use a catheter tip for point to point sequential ablation? Concept of One Shot Ablation - the right tool for the job?

42 Technology Update Sequential RF Cryoballoon PVAC Cardiofocus HIFU Mesh

43 RF vs Cryoablation for AF Sequential RF Cryoballoon

44 Cryoablation for AF Arctic Front Balloon Achieve Catheter

45 Cryoablation for AF

46 RF vs Cryoablation for AF RF & cryoablation have similar efficacy (for PAF) Have similar complication rates Procedure time shorter for cryoablation Less radiation Single versus double trans-septal puncture More pleasant procedure for operator One-shot techniques don t allow ablation of Aflutter / AVNRT / AP or creation of linear lesions One-shot techniques require touch-up in some patients

47 Who to Refer for AF Ablation Prime indication for ablation is to improve QOL (symptoms) Failed at least 1 AA drug (Class 1 HRS) Prefer to avoid medication 1 st line therapy for AF (Class 2a) If AF well controlled on AA drugs, continue as there are rare but catastrophic risks of ablation

48 Who to Refer for AF Ablation Best candidate Young (<70), healthy, paroxysmal, structurally normal heart Refer PAF early to acheive control and treat risk factors Chronicity of AF predicts poor outcome Not a magic bullet like WPW ablation At least 30% of patients need a redo procedure

49 Who to Refer for AF Ablation Not appropriate to ablate with the goal to stop anticoagulation Ablation is not an alternative to anticoagulation No data to support improved stroke risk after AF ablation

50 Complications Early (within 24h) Tamponade 1% Stroke 1% Vascular access complications 3% Phrenic nerve injury (RSPV ablation) 6% cryoablation (usually transient)

51 Complications Delayed Atrioesophageal fistula 1 in 3000 Day 5 30 Fever, odynophagia, non-specific symptoms CT (free gas), NOT endoscopy Left Atrial Flutter 5% Pulmonary vein stenosis 1% Delayed cardiac tamponade

52 Anticoagulation At least 2 months post ablation At 2 months continue based on stroke risk profile CHADS-VASC score Recurrent AF is common and may be late 2 to 3 years and may be asymptomatic Stroke risk increases with age despite prior ablation

53 Assessing Success Definition Freedom of symptomatic AF episodes off AADs primary objective No need to monitor for AF during blanking period If asymptomatic no monitoring is indicated as it has no impact on the need for anti-coagulation Asymptomatic AF is not an indication for redo ablation Intermittent ECG is sufficient (unless part of a clinical trial)

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