Effect of Amiodarone on the Procedure Outcome in Long-standing Persistent Atrial Fibrillation Undergoing Pulmonary Vein Antral Isolation

Background: Atrial Fibrillation (AF) is the most prevalent sustained clinical arrhythmia
encountered in clinical practice. Its prevalence is 0.4-1% in the general population and
greater than 8% in individuals >80 years of age. An estimated 2.5million individual in North
America and 4.5 million in Europe are affected by AF (1). There are two fundamental
principles in the management of AF; 1) anticoagulation to reduce the risk of
thromboembolism, 2) ablation therapy or drugs or both to control the arrhythmia (2).

Amiodarone, a potent antiarrhythmic drug, is recommended for both atrial and ventricular
arrhythmia. It has a combination of Beta-blockade, calcium-, sodium- and potassium-channel
blockade effect. Most importantly, the potassium-channel blockade slows repolarization,
causing an increase in the action-potential duration and in the refractoriness of the
cardiac musculature (3). As the myocardium remains unresponsive, the premature
depolarizations which were previously causing AF are prevented from propagation.

During the ablation procedure, mapping electrograms using circular mapping catheter and
provocative maneuvers such as administration of isoproterenol in incremental doses are
commonly used to aid in identification of pulmonary vein (PV) and non-PV triggers. In
addition, areas with complex fractionated atrial electrograms (CFAE) are identified and
eliminated by ablation. In patients with LSP, inclusion of PV and non-PV triggers as
ablation targets, improves the procedure outcome.

As Amiodarone increases the refractoriness of the myocardium, it is possible that under the
effect of Amiodarone some of the focal triggers could be masked or remain unidentified
during mapping or isoproterenol-provocation. These unrecognized triggers could cause
recurrence of AF during the post-ablation period. In other words, discontinuation of
Amiodarone at least 5-months before ablation could result in unmasking of all the focal
triggers that would have otherwise stayed unrecognized and eliminating those triggers would
significantly improve the success rate of the procedure.

Our study aims to investigate the role of Amiodarone in influencing the procedure outcome in
LSP-AF patients undergoing catheter ablation.

Hypothesis: Withdrawal of Amiodarone 5 months before procedure results in unmasking of
additional focal triggers, ablation of which leads to an improved procedure outcome in
LSP_AF patients.

Inclusion Criteria:

1. History of LSP AF

2. Age > 18 years

3. Willing and ability to understand and sign an informed consent

4. Patients on chronic Amiodarone therapy (≥ 3 months)

Exclusion Criteria:

1. Unstable angina

2. Concomitant treatment with other class I or III antiarrhythmic drugs

3. Myocardial infarction within past 3 months)

4. Presence of any disease that is likely to shorten life expectancy to < 1 year

5. Symptomatic heart failure, NYHA III or IV

6. Contraindications for Amiodarone

7. Chronic liver diseases

8. Pregnant or breast-feeding mothers

Primary Outcome Measure:

Recurrence of AF, atrial flutter or atrial tachycardia

Secondary Outcome Measures:

Difference in the occurrence of relapse between the control and the study groups

Study design:

This is a multi-center, prospective study in which consecutively enrolled patients treated
with Amiodarone for long standing persistent AF will be randomized to either the study or
the control group.

Study group: Amiodarone therapy will be stopped at least 5-months before ablation procedure
and ablation will be performed off Amiodarone. Patients will not take Amiodarone during the
blanking period (8 weeks post-ablation).

Control group: Patient will continue taking Amiodarone before, during and after ablation (8
weeks post-ablation).

After the blanking period, everybody would be off Amiodarone unless they have recurrence.
Anti-arrhythmic drugs other than Amiodarone would be tried if patient develops recurrence
and repeat ablation would be considered.

Follow-Up:

Patients will be followed up for 12 months post-ablation. An ECG and telemetry transmission
monitor report will be obtained in all patients at each follow-up examination.

Patients will be supplied with an Event Recorder for trans-telephonic rhythm transmission
(telemetry) for 5 months after ablation, and will be asked to transmit their rhythm data
every time they had symptoms compatible with arrhythmias; and at least once a week, even if
they were asymptomatic. Holter monitoring will be performed at 6-month post-ablation. The
arrhythmic episodes will be documented based on ECG, Holter data, Event Recorder data and/or
implanted device data (when available).

Inclusion Criteria:

1. History of LSP AF

2. Age > 18 years

3. Willing and ability to understand and sign an informed consent

4. Patients on chronic Amiodarone therapy (≥ 3 months)

Exclusion Criteria:

1. Unstable angina

2. Concomitant treatment with other class I or III antiarrhythmic drugs

3. Myocardial infarction within past 3 months)

4. Presence of any disease that is likely to shorten life expectancy to < 1 year

5. Symptomatic heart failure, NYHA III or IV

6. Contraindications for Amiodarone

7. Chronic liver diseases

8. Pregnant or breast-feeding mothers