Effectiveness Study of Circumferential vs. Segmental Ablation in Paroxysmal Atrial Fibrillation

Despite more than a decade of clinical experience and investigation, the optimal approach to
ablation of paroxysmal atrial fibrillation (PAF) still remains controversial. There are
currently two strategies for ablation of PAF: (1) circumferential pulmonary vein ablation
(CPVA) and (2) segmental pulmonary vein isolation (SPVI). There are advantages and
disadvantages associated with each method. In the CPVA method (1), contiguous ablation
lesions are created to encircle the two left and right pulmonary veins (PVs), guided by a
three-dimensional (3D) electroanatomic mapping system (Carto, Biosense Webster, Inc. or ESI
NavX, St. Jude, Inc.) with a 3D left atrial (LA) geometry created either by using the mapping
catheter or by importing a pre-recorded 3D computed tomography (CT) image. In the SPVI method
(2), electrical potentials recorded at the PV ostium, that represent myocardial connections
between the LA and PVs, are ablated at the PV ostium or just proximal to the PV ostium in the
PV antrum. In this approach, ablation is performed segmentally at multiple sites around the
PV ostium or antrum, until mapping with a circular catheter demonstrates pulmonary vein
isolation.

The reported success rates for SPVI for prevention of recurrence of PAF range from 60-87%
(2-4) with most recurrences associated with recovery of PV conduction. Therefore, the success
of SPVI for treatment of PAF appears to be related to in large part to permanent elimination
of the triggers of AF. In a retrospective study by Sawhney et al, overall 5-year outcome
after SPVI for PAF was similar to that for short-term follow up less than or equal to 2
years. However, late recurrences after 2 years did occur (up to 22.5%) and repeat ablation
was often required to maintain freedom from symptomatic PAF (5).

Even though success rates for CPVA have been reported to be higher (up to 90%), most CPVA
procedures previously reported included left atrial linear ablation (LALA), additional
ablation lesions or lines connecting the mitral valve to the posterior pulmonary veins or
along the roof of the left atrium. Thus the success of CPVA may be due in part to ablation of
substantially larger amounts of atrial tissue (6-7). However, additional ablation (LALA) may
cause potential pro-arrhythmic effects that lead to development of atypical left atrial
flutter (8).

Compared to SPVI, CPVA resulted in higher success rates and lower fluoroscopy time in one
study by Arentz et al (9). However, that study included subjects with both PAF and persistent
AF, and those with persistent AF have potentially different underlying mechanisms.
Furthermore, two other randomized studies comparing the efficacy of PVI and CPVA have shown
conflicting results (10-11).

Thus, we will initiate this randomized controlled study to evaluate the efficacy of CPVA
versus SPVI in subjects undergoing ablation of paroxysmal atrial fibrillation only.

Inclusion Criteria:

1. Patients with paroxysmal atrial fibrillation, whose episodes have never been
documented to exceed 48 hours duration

2. Patients with a clinical indication for ablation

3. Patients greater than 18 years of age.

4. Patients willing and able to give informed consent.

5. Patients with concurrent atrial fibrillation and atrial flutter are allowed.

Exclusion Criteria:

1. Patients with medical conditions that would limit participation for the entire
duration of the study.

2. Patients that are pregnant (all females of child-bearing potential must have a
negative pregnancy test within 1 week of enrollment).

3. Patients having undergone prior AF ablation

4. Patients with paroxysmal atrial fibrillation whose episodes last greater than 48 hours

5. Patients with persistent AF