CATHETER ABLATION OF ATRIAL FIBRILLATION – BORDEAUX 2006-7

Surgical or catheter ablation of atrial tissue are the only curative treatments for atrial fibrillation (AF). The major goal of catheter ablation of AF is restoration of normal sinus rhythm to relieve symptoms associated with AF, and minimization or suppression of the associated risks of blood clot formation, cardiac failure and increased mortality.
 

Radiofrequency energy is delivered via intracardiac catheter to cauterize the sources (ectopic foci or stable circuits) triggering or maintaining the episodes of AF, usually in the pulmonary veins and/or segment the atrial tissue by linear barriers interrupting the errant electrical waves responsible for maintenance of AF.

Isolation of pulmonary veins cures the paroxysmal (intermittent) form of AF in 80% of patients (without any medication) and improves an additional 10% (with an antiarrhythmic drug but without need for anticoagulants).The longer the episodes of AF, the more diffuse the atrial abnormality outside the pulmonary veins In persistent AF (lasting> 48h or history of electrical cardioversion) or permanent FA, isolation of pulmonary veins is less effective alone and should be associated with ablation of atrial tissue to increase the success rate to 90%. However, recovery of tissue – even minimal during the healing process can require an additional ablation either early (first week) or after 1 - 3 months of follow-up.

Preablation management
 

For safety reasons( avoiding embolization of clot during catheter manipulation) the patient should take oral anticoagulation (Coumadin not aspirin) at an optimal therapeutic range ( lNR 2-3) for at least 1 -2 months before the procedure to minimize the risk of clot formation. In addition a transesophageal echocardiogram should be performed a few days before hospitalization to confirm the absence of a clot, notably in the left atrial appendage which would postpone the date of intervention.

Anticoagulants should be interrupted 48 hours before the operative day, antiarrhythmic drugs will be stopped on admission.

Catheter approaches

General anesthesia is rarely performed in adult patients to minimize the associated risks of infused drugs. Under slight sedation and local groin anesthesia, 3 catheters are typically introduced through one or two femoral veins for mapping and ablation. The mapping catheters involve multiple electrodes mounted in a longitudinal or circumferential shaft. Other
 

Configurations including investigational designs may be used for individual situations.
The ablation catheter has an irrigated tip to exclude local clot formation and allow greater energy delivery if needed (at thick parts of cardiac tissue). In the absence of patent foramen oval (interatrial septal hole creating a pathway between the heart chambers found in 20% of patients), a transseptal puncture is required to access the left atrium.

Ablation strategy is individualized. Two or three physicians are involved during the procedure: for catheter positioning and for collection analysis and interpretation of intracardiac signals obtained during conventional or computerized mapping.

RF ablation is performed around the orifice of pulmonary veins, one by one or two by two, with a limited level of energy to avoid narrowing of the vessel or atrial perforation. Venous isolation is successfully performed in l00% of cases. In paroxysmal AF, PV isolation terminates AF in 60 – 70 % of cases. In others, additional ablation is performed at the appropriate sites until termination of AF.

Ablation in the right atrium (cavotricuspid isthmus) is also performed systematically (except if previously done) to prevent right atrial flutter; linear block is here successfully achieved in 99% of cases.
In persistent AF, (lasting> 48 hours or history of electrical conversion) PV isolation is still the first step but rarely sufficient alone.

The second step is to apply radiofrequency energy to eliminate spots of extrapulmonary vein sources and areas of rapid activity identified by mapping in the left atrium and afferent veins, and sometimes in the right atrium.

In the most resistant cases (usually long lasting AF) the last step is linear ablation analogous to surgical incision. Linear ablation is performed in the left atrium between the two superior PV (roof line) and/or from vein to mitral annulus( mitral' isthmus') with an achievement of linear block in 90% Chronic AF can be terminated in 85% of cases using the above protocol.

The success is dependent on the feasibility of achieving continous & coalescent cauterizing points to create a complete barrier. Any gap in the line even of a millimeter size allows crossing of electrical impulses annihilating the ablation result. A persistent gap is due either to a too thick atrial wall or (unpredictable) recovery of atrial tissue during the 1 - 4 week healing process following ablation. Pain or discomfort associated with cauterization are controlled by Midazolam & Morphine.

Duration of operation and hospital stay

The procedure duration varies from one to four hours depending on individual
conditions:
- the number of ectopic sources in the atrial tissue (outside the pulmonary veins)
which require more mapping time;
- linear ablation of atrial tissue substrate which is determined by the cardiac
thickness all along its course, varies from one patient to another and cannot be
precisely evaluated by preablation imaging parameters.

The end-point of the procedure is the achievement of local block in all targeted
structures (veins and isthmuses) In addition, inability to induce sustained AF despite multiple pacing maneuvers is obtained in 90 % of cases of paroxysmal AF.

A second procedure may be needed within 3-5 days in 25% of subjects for
complementary ablation: either due to partial recovery of ablated tissue or
secondary revealed sources. In difficult cases of multiple or unmappable ectopic foci, a second linear ablation may be required in the left atrium. In chronic AF which is associated with widespread atrial abnormalities reablation is needed in 45% of cases to eliminate atrial tachycardias representing remnants of abnormal tissue.

Patients are hospitalized 4 to 6 days depending on the number of procedures
required. Typically they return to the normal care unit after ablation and are
ambulatory 12 to 24 hours later. They are monitored by telemetry during the next 3 days when any recurrence of arrhythmia is most likely to occur. The likelihood of recurrence decreases over the next month.

The patients are usually admitted on Monday and can leave the hospital for the week-end, if there are no complications. They may stay in the region for the week end and return the following Monday for outpatient evaluation which could result in rehospitalisation if needed.
The occurrence of complications may increase the duration of the hospitalization and therefore the cost. In our experience, this is observed in 2.5% of patients.
 

In the absence of arrhythmia recurrence, patients can return home and resume normal activities thereafter. Anticoagulants are recommended for at least 1 -3 months after ablation and then can be interrupted in the absence of AF and other risk factors. Antiarrhythmic mediations are recommended for 1 - 3 months after ablation in persistent forms of AF to enable the atrium to recover (process named "remodeling").

Population of patients

Catheter ablation of AF is performed since 1994 in Bordeaux. As of October2006, over 4500 patients have been treated and at least ten cases of atrial flutter or fibrillation are treated every week. The clinical characteristics of patients cover a wide spectrum of age (15-82 years average 52) with 78% male and 22% female and 80% of paroxysmal versus 20% of persistent/chronic AF. All patients were resistant or intolerant to an average of 3 antiarrhythmic drugs and experienced at least weekly episodes of AF at their referral.

Some patients have documented sinus pauses following A F paroxysms and were cured by AF ablation thus avoiding pacemaker implantation. Twelve per cent report a previous embolus event, most in the brain circulation. In patients with heart failure and permanent AF, the restoration of sinus rhythm is associated with a significant improvement of ventricular function in 80% of cases.

Risks associated with AF catheter ablation

The operative mortality is presently 0% in our department, 0.1% risk is a reasonable estimation by analogy to other catheter procedures. The other risks of catheter ablation of AF are: bleeding in the pericardial bag surrounding the heart and requiring drainage (- 0.5 %), embolic event (0.2%) and groin access hematoma (4%) There is no risk of sinus node or AV node damage caused by ablation which would require pacemaker implantation. World-wide there have been deaths reported by creation of a fistula with the esophagus using high energy power ( > 50 watts), manifesting beyond 2 days of the procedure. We have not observed this complication.

Pulmonary vein narrowing if it did occur would not usually cause symptoms. Out of 4500 patients treated in our institution, 5 developed symptoms due to PV narrowing (> 70 % of lumen diameter) and requires angioplasty and stenting.

The above risks compare very favourably to the reported complication rates
associated with A F, and long-term use of antiarrhythmic drug and anticoagulants.

Procedure cost

This cost is fixed by the public health administration 1097 euros per day,
4000 euros for all single use catheters the catheters including Lasso and irrigated tip catheters.
The cost for a private service ( operators: Dr M. Hai'ssaguerrle/ P.Jais / M. Hocini) is 4000 euros ( hospital and physician charges) Therefore, the total cost of AF catheter ablation depends on the duration of hospital stay which is a function of the difficulty of individual ablation case.

The typical hospital stay of 5 days with an ablations session including pulmonary vein isolation and ablation of the right and left atria costs about 13933 euros. This provisional cost is asked on the hospital admission date. One day more or less would be 1183 Euros more or less.

The current waiting time for a procedure is 12 months.
For patients accompanied by a family member and without local accommodation a, bed and breakfast is provided in the same room (67,45 euros/day). Patients should come with personal clothes as it is possible to walk outside and patients are expected to generally wear their own clothes including pajamas. As the hospital only provides small towels you may wish to bring your own towels.

Here is a link to a recent (Jan 2007) description of their approach to CA:

http://www.a-fib.com/BostonA-FibSymposium2007.htm 

In addition, looking through the Panel Discussion at the 2006 Boston Symposium on this site is one way to compare their approach to that of others. (The report on the 2008 Symposium will update this information.)