RF Ablation of Atrial Fibrillation in Valvular Heart Surgery Patients

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RF Ablation of Atrial Fibrillation in Valvular
Heart Surgery Patients

• Željko Sutlic

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Introduction

• The incidence of chronic atrial fibrilation (AF)
  is age dependent
• 1 of the general population
• 4 in pts gt 60 years
• 7 in pts gt 70 years
• 60-80 in pts with significant mitral valve
  disease

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AF - TYPES

• paroxsismal AF
• persistant AF
• permanent AF

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Criteria for Success

• Sinus Rhythm
• Absence of intermittent AF
• Absence of atrial flutter
• Atrial transport function
• Restricted antiarrhythmic medication

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Criteria

• Indication for mitral valve repair/replacement or
  coronary artery disease
• Chronic atrial fibrillation (gt6 months)
• Electrocardiographical confirmation of diagnosed
  chronic atrial fibrillation by 24 hour holter
  monitoring
• EF gt 30
• Age 18 80 years
• Informed consent

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Atrial fibrillation in Patients Undergoing Mitral
Valve Surgery Why AF Surgery?

• Incidence of AF varies between 30 50
• Curative AF surgery can eliminate the need for
  anticoagulation by restoring sinus rhythm,
  particulary important in patients having valve
  repair
• Rate of anticoagulation-related bleeding after
  mechanical valve surgery is between 0,3 to 4,9
  events/ patient year
• Bleeding rates with mitral bioprosthesesare less
  but stillsignificant (0,6 2,1 episodes/patient
  year) in part due to the need for anticoagulation
  for AF

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Atrial Fibrillation Surgical Therapy

• Cox developed the Maze Procedure first
  performed in 1987 at Barnes Jewish Hospital
• High rate of surgical cure for atrial
  fibrillation (gt90) without antiarrhythmic
  therapy
• Indications
• Drug refractory AF
• Arrhythmia intolerance
• Recurrent thromboembolism

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Atrial fibrillation and Mitral Valve Disease

• Should all patients with atrial fibrillation who
  are referred for mitral valve surgery undergo a
  concomitant Cox-Maze procedure?
• Let's look at our long term surgical results in
  these patients!

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Cox-Maze III Procedure

• Cox-Maze III first performed in 1988
• Maze-like surgical incisions
• Based on theory of multiple macro-reentrant
  circuits

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The Cox Maze ProcedureEvolution of the Surgical
Approach

• The Cox Maze I was abandoned because of a high
  incidence of chronotropic incompetence and
  pacemaker implantation
• The Cox Maze II was replaced because of its'
  technical difficulty
• The Cox Maze III has remained the gold standard
  since 1988 and has extraordinary long term
  efficacy

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The Cox-Maze ProcedureSurgical Objectives

• Cure of atrial fibrillation
• Restoration of A-V synchrony
• Preservation of atrial function
• Discontinuation of anticoagulation and
  anti-arrhythmic drugs

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Cox-Maze III ProcedurePatient Populations

• Lone atrial fibrillation
• Atrial fibrillation in association with organic
  heart disease
• valvular heart disease
• ischemic heart disease

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Freedom form AF All Patients
Cox JL. Surg Treat of AF, San Francisco, June 2003
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Freedom from AF LM versus CM
Cox JL. Surg Treat of AF, San Francisco, June 2003
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Efficacy of Surgical Maze Procedure for Atrial
Fibrillation
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Cox-Maze III Procedure with Mitral Surgery
Washington University Experience

• 65 consecutive patients between January 1988
  May 2003 mean follow-up 3.6 years
• Avarage duration AF 5.2 years (0,528 years)
• Paroxysmal AF 41
• Operative mortality 1/65 ( 1.5 )
• Freedom from AF at 10 years 97
• No late strokes!

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Advantages of the COX-MAZE III Procedure

• High cure rate (gt90)
• Proven long-term efficacy
• Applicable to both persistent and paroxysmal AF
• Eliminates the late risk of stroke in a high risk
  population
• Requires no additional devices except for a
  cryoprobe

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Shortcomings of the COX-MAZE III Procedure

• Requires cardiopulmonary bypass and an arrested
  heart
• Adds to cross-clamp time
• Few surgeons perform the operation due to its'
  complexity
• Significant morbidity
• pacemaker requirement and left atrial dysfunction

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Cox-Maze III Procedure for AF Postoperative
Management

• Diuretics
• Lasix
• Spironolactone
• Coumadin
• 3 months
• Discontinue if in NSR
• Anti-arrhythmic drugs
• 2 months
• Discontinue if in NSR
• Postoperative sinus node dysfunction
• 10 15 of patients
• Wait 7-10 days before implanting pacemaker

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The Cox Maze ProcedureGoals of a Less Invasive
Approach

• Preserve the high success rates of the Cox-Maze
  III procedure while decreasing its' morbidity
• Simplify and/or decrease the number of atrial
  incisions to shorten the procedure and increase
  its' adoption rate among surgeons
• Replace surgical incisions with linear lines of
  ablation using various energy sources
• Cryosurgery
• Radiofrequency
• Microwave
• Laser
• Ultrasound

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Radiofrequency energy

• similar to electrocautery
• very fast AC current
• no depolarisation of the heart
• monopolar or bipolar
• irrigated or not irrigated (early)

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Dry vs- Irrigated Electrode Tissue Heat
Distribution
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Complications of RF Ablation for Atrial
Fibrillation

• CVA
• TIA
• Tamponade
• Aortic tear
• Pulmonary vein stenosis
• Damage to MV apparatus
• Phrenic nerve injury
• Coronary artery injury

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Surgical procedure (began on april 2003)

• MVR and TVP 6 patients
• MVR and CABG 1 patient
• average aortic clamp time 94 42 min
• average pump time 124 25 min

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Table 1. Clinical characteristics (n7)
3/4
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Table 2. Echocardiographic variables
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Table 3. Single case (male, 58 years old, MVR
TVP)
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Surgery for Atrial FibrillationEstablished
Facts and Surgical Approach

• We have very effective, though invasive,
  operation with high success rates
• Patients who are candidates for Cox Maze
  procedure should not be deprived of a curative,
  known procedure for a theoretical lesion set
  performed with unproven technology
• New procedures and technology should be subject
  to rigorous prospective clinical trials
• New lesion sets should be based on known
  mechanisms of atrial fibrillation

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Will There Be a Role for Surgery in the Future?

• Yes, for the symptomatic patient
• Who requires other concomitant cardiac surgical
  procedures
• Coronary artery disease
• Valvular heart disease
• Congenital disease
• With prior thromboembolic complications
• For persistent and "permanent" atrial
  fibrillation
• Possibly
• With paroxysmal atrial fibrillation if performed
  via minimally invasive techniques

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Catheter Ablation Techniques for Atrial
Fibrillation Conclusions

• Effective (60-80) for drug refractory paroxysmal
  AF with pulmonary vein triggers
• Targets PV-LA junction, with linear line to MVA,
  possible linear lesion across Bachman's bundle
• Prolonged procedures, requires transseptal access
  to the LA
• Lesions constrained by biophysical properties of
  tissue
• Complications approach 5
• TIA/CVA
• Pulmonary vein stenosis
• Cardiac tamponade
• Aortic tear, coronary injury
• One of multiple tools available

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Everything should be made as simple as possible.
But not simpler.

• Albert Einstein

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