Presentation on theme: "Catheter Ablation in the Treatment of Atrial Fibrillation"— Presentation transcript:
1 Catheter Ablation in the Treatment of Atrial Fibrillation
2 Atrial Fibrillation First described in 1903 by Hering Most common sustained arrhythmiaThe irregularity and inequality of heart rhythm associated with atrial fibrillation was first described by Dr. Hering in 1903.Atrial fibrillation is by far the most common sustained arrhythmia diagnosed and treated by physicians. It may be either paroxysmal or chronic. Paroxysms may be brief or lengthy, frequent or infrequent; they may be benign or result in marked symptoms.1
3 Atrial fibrillation accounts for 1/3 of all patient discharges with arrhythmia as principal diagnosis6% PSVT6% PVCs18% Unspecified4% Atrial Flutter9% SSS34% Atrial Fibrillation8% Conduction Disease10% VT3% SCD2% VFBaily D. J Am Coll Cardiol. 1992;19(3):41A.
4 Atrial Fibrillation What is Atrial Fibrillation? Chaotic circular impulses in the atriaSeveral reentrant circuits moving simultaneouslyAtrial rates300 to 600 beats per minuteVentricular rates regulated by the AV nodeIrregularly irregular due to partial depolarization of AV nodeResults in loss of AV synchrony20% to 30% decrease in cardiac output
5 Incidence and Prevalence Prevalence increases with age4.8 % in the age groupIncreases to8.8% in the age groupDuring the next 7-8 years, the number of people over the age of 80 is expected to quadruple
6 Atrial Fibrillation Demographics by Age U.S. population x 1000Population with AF x 100030,00020,00010,000Population with atrial fibrillation500400300200100U.S. population<55- 910- 1415- 1920- 2425- 2930- 3435- 3940- 4445- 4950- 5455- 5960- 6465- 6970- 7475- 7980- 8485- 8990- 94>95Age, yrAdapted from Feinberg WM. Arch Intern Med. 1995;155:
7 Stages of Atrial Fibrillation ParoxysmalPersistentPermanent
8 Stages of Atrial Fibrillation Paroxysmal (23% of AF population)Self limitingSpontaneous conversion to sinus rhythm within 24 hrs after onset is commonOnce the duration exceeds 24 hrs, the likelihood of conversion decreasesAfter one week of persistent arrhythmia, spontaneous conversion is rare30% of these patients develop “Persistent” AF
9 Stages of Atrial Fibrillation Persistent (38% of AF population)Requires intervention to restore normal rhythmCardioversionElectrical or Chemical (drugs)Can lead to electrophysical and structural changes in the myocardium (remodeling) that can lead to “Permanent” AFAF with duration of greater than 7 days rarely spontaneously converts
10 Stages of Atrial Fibrillation Permanent (39% of AF population)Unable to convert Electrical or Chemical (drugs)
11 Mechanisms of AFTheories of the mechanism of AF involve 2 main processes:- Enhanced automaticity in one or several rapidly depolarizing foci- Reentry involving one or more circuits
13 Mechanisms of AFRapidly firing atrial foci, located in one or several pulmonary veins (PVs), can initiate AF in susceptible patientsFoci also can occur in RA and infrequently in the superior vena cava or coronary sinus
15 Factors Involved in the Pathogenesis of AF Studies in man have shown that increased inhomogeneity of refractory periods and conduction velocity is present in AF patients.Structural changes in atrial tissue may be one of the underlying factors for dispersion of refractoriness in AF.Other factors involved in the induction or maintenance of AF include premature beats, the interaction with the autonomic nervous system, atrial stretch, anisotropic conduction, and the aging process, vein of Marshall……….
17 Atrial Fibrillation: Clinical Problems Embolism and stroke (presumably due to LA clot)Acute hospitalization with onset of symptomsAnticoagulation, especially in older patients (> 75 yr.)Congestive heart failureLoss of AV synchronyLoss of atrial “kick”Rate-related cardiomyopathy due to rapid and irregular ventricular responseRate-related atrial myopathy and dilatationChronic symptoms and reduced sense of well-being
18 Therapeutic Approaches to Atrial Fibrillation AnticoagulationAntiarrhythmic suppressionControl of ventricular responsePharmacologicCatheter modification/ablation of AV nodeCurative proceduresCatheter ablationSurgery (maze)
20 Antiarrhythmic Therapy for Atrial Fibrillation AdvantagesHigh efficacy for some patients, at least initially (< 50% of all patients)Low initial costNoninvasiveDisadvantagesHigh recurrence rateHigh long-term costNon-curativeAdverse effectsPotential proarrhythmia
21 Antiarrhythmic Suppression DrugsConversion of AFClass 1A (decrease conduction velocity, increase refractory periods of cardiac tissue, suppress automaticity)QuinidineProcainamideClass III (decrease conduction velocity, increase refractory periods of cardiac tissue, suppress automaticity)AmiodaroneSotalolIbutilide (Corvert)Dofetilide
22 Antiarrhythmic Suppression DrugsMaintenance of normal rhythmClass 1AClass IIIClass 1C (decrease conduction velocity)FlecainidePropafenoneDrug choice depends upon patient’s underlying heart disease
23 Nonpharmacological Approaches to Atrial Fibrillation Pacemaker therapy2. Ablation3. Surgery
24 RF Ablation Techniques Focal ablation of PV (Pulmonary vein) triggersSegmental PV isolationWide Area Circumferential AblationAblation of Fractionated Complex ElectrogramsTargeted ablation of ganglionated autonomic plexi in the epicardial fat pads
26 Focal Ablation of Atrial Fibrillation 95% of foci are located within a pulmonary vein ( PV).Focal sources of AF may be found in the RA, LA, coronary sinus, superior vena cava or vein of Marshall.Haissaguerre M, Jais P, Shah DC, et al. Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary veins. N Engl J Med 1998;339:659–66.Chen SA, et. al: Initiation of atrial fibrillation by ectopic beats originating from the pulmonary veins: Electrophysiologic characteristics, pharmacologic responses, and effects of radiofrequency ablation. Circulation 1999;100:
35 Focal Ablation of Pulmonary Veins Complications The most common complications associated with the focal ablation of the PVs are pericardial effusion (<4%), transient ischemic episodes (<2%) and symptomatic PV stenosis <2%).Asymptomatic PV stenosis may occur at as many as 40% of sites at which focal ablation is performed.Symptomatic PV stenosis seems to be infrequent if the number of radiofrequency applications delivered within PV is kept to a minimum.
42 Segmental PV Isolation Limitations associated with focal ablation have prompted the development of other techniques for eliminating the PV arrhythmias.Anatomically PV isolation has significant advantages over focal ablation.
44 Dissociation of the PV potential after successful isolation
45 Segmental Ostial Pulmonary Vein Isolation The initial experience with segmental ostial ablation of PVs guided by PV potentials is encouraging, with a long-term success rate of 90% in patients with paroxysmal AFMinimal risk of PV stenosis when the power of radiofrequency energy applications is limited to 30 W.
47 Circumferential Ablation It is an anatomic approach in which circumferential lines of block are created using 3D maps ( Carto, NavX..) around the ostia of PVs for isolation of PVs from LA.Additional linear lesion from LIPV to mitral annulus for preventing LA incisional tachycardia ( 2%).Additional linear lesions (posterior, roof, right isthmus….) may be created deepening on operator’s preference.Pappone C, et al. Atrial electroanatomic remodeling after circumferential radiofrequency pulmonary vein ablation: efficacy of an anatomic approach in a large cohort of patients with atrial fibrillation. Circulation 2001;104:2539–2544.
57 Circumferential Ablation Effective in both paroxysmal and chronic AF (81%, 76%)Bipolar amplitude < 0.1 mv inside and around the lesion may be acceptable for showing PV isolation.
58 Post Circumferential PV ablation Bipolar amplitude < 0.1 mv inside the lesion
59 Mitral Isthmus LineThe addition of mitral isthmus line to the PV disconnection may allow a significant improvement of sinus rhythm maintenance rate, particularly in patients with persistent AF, without the risk for major complications.J Cardiovasc Electrophysiol, Vol. 16, pp , November 2005
60 Complication rates following circumferential pulmonary vein ablation Death 0%Pericardial effusion 0.1%Stroke 0.03%Transient ischemic attack 0.2%Tamponade 0.1%Atrio-esophageal fistula 0.03%Pulmonary vein stenosis 0%Incisional left atrial tachycardia 6%Phrenic nerve injury
61 Topographic Variability of the Esophageal Left Atrial Relation
62 CT reconstruction of the LA, the pulmonary veins, and the esophagus
63 Topographic Variability of the Esophageal Left Atrial Relation
67 Ablation of Fractionated Electrograms Hypothesis being that these are consistent sites where fibrillating wavefronts turn or split.By ablating these areas the propagating random wavefronts are progressively restricted until the atria can no longer support AF.Nademanee demonstrated 70% freedom from AF following a single procedure for permanent AF patients.Nademanee K, et al. A new approach for catheter ablation of atrial fibrillation: mapping of the electrophysiologic substrate. J Am Coll Cardiol 2004;43:2044–53.
68 Segmental Ablation vs. Circumferential Ablation? Is either of the two ablation strategies superior to the other?Oral et al. showed that, during the 6 months following a single catheter procedure, Circumferential Ablation was associated with a significantly better outcome with no differences between the two ablation strategies in the complication rates.Schmitt et al. reported opposite results to those of Oral et al.The opposite results in the two studies were obtained because of the large variability in the success rate observed in patients undergoing Circumferential Ablation (88 vs. 47%) while the success rates in patients undergoing Segmental Ablation remained unchanged (67 vs. 71%).
70 Frequently Asked Question Who is currently a candidate for AF ablation?
71 Patient selection criteria Inclusion criteriaAt least one monthly episode of persistent symptomatic AF orAt least one weekly episode of paroxysmal AF orPermanent AFAndAt least one failed trial of antiarrhythmic drugs orMore than one antiarrhythmic drug to control symptomsExclusion criteriaNYHA functional class IVAge > 80 yearsContraindications to anticoagulationPresence of cardiac thrombusLeft atrial diameter ≥ 65 mmLife expectancy < 1 yearThyroid dysfunctionRecent updatesPatients with mitral and/or aortic metallic prosthetic valves arenot excludedPrevious repair of atrial septal defects is not an absolute contraindication
72 Frequently Asked Question AF ablation for asymptomatic individuals?
73 Asymptomatic Patients To date there is no evidence that treatment of AF by ablation improves mortality, although there are uncontrolled data suggesting that this may be the case.Therefore, asymptomatic patients should not be offered curative ablation of AF, except in the case of those patients undergoing cardiac surgery who may benefit from surgical ablation of their AF as an adjunctive procedure.There is also evidence that patients with heart failure have significant improvements in left ventricular function following successful catheter ablation of AF.
75 ConclusionFor many patients with a previously untreatable heart rhythm, ablation has dramatically improved their symptoms by restoring and maintaining sinus rhythm.Preliminary randomized studies of catheter ablation of AF provide evidence that ablation (with or without concurrent anti-arrhythmic drug use) effectively improves maintenance of sinus rhythm when compared with current anti-arrhythmic drugs.Although prognostic and quality of life data from long term randomized trials of catheter ablation for AF are still in preparation, the non-randomized data comparing ablation to continued medical treatment suggests a strong benefit from ablation.