A Study of Strategies for Electrical Isolation of Pulmonic Veins for Curative Treatment of Atrial Fibrillation

Usually there are 4-5 PVs in each person that bring blood form the different lobes of the
lung into the LA. Typically the inside lining of the LA extends for 3-7 mm inside the PVs
around the entire circumference as they connect (ostium; os) in the form of finger like
projections. These projections are thought to be the sites that initiate AF. The procedure
involves careful definition of the finger like projections between the LA and PV os using
the circular mapping catheter (Lasso). The connections produce specific pattern of
electrical recordings which are targeted using the ablation catheter that utilizes
radio-frequency energy to create local burns at the point of contact with the inside of the
heart. A successful burn destroys these finger-like projections which can be appreciated by
loss of the characteristic electrical recordings which were seen pre-ablation. Using this
technique, a series of radiofrequency ablation lesions are delivered around the
circumference of PV, the end point being obliteration of all electrical recordings between
the left atrium and the PV of interest (also called "Electrical Isolation" of PV from the
rest of the LA). At this time the ablation procedure for AF involves electrical isolation of
either those PVs that have been shown to be the sites from where AF starts (arrhythmogenic
PV) or empirically isolating all the PVs that the patient has (typically 4-5). There is lack
of data showing benefit of one technique over the other. Additionally, in order to create
radiofrequency lesions or burns inside the heart, two different catheter technologies have
been approved and are currently in use: 1) radiofrequency delivery using a standard 4-mm tip
or 8-mm tip catheter, which creates burns at the point of catheter contact that are
approximately 5 mm deep and 2) delivery of radiofrequency energy via saline irrigated cool
tip catheter which is capable of creating deeper burns (5 - 10 mm). Once again, for
electrical isolation of pulmonic veins in pts with AF, there is no data that proves the
benefit of either catheter technology over the other.

PURPOSE AND DURATION: The objectives of the proposed research project are to study:

- The effectiveness of electrical isolation of only the arrhythmogenic pulmonic veins
(PV; partial isolation) vs. electrical isolation empirically of all 4 PV (total
isolation) on long-term (1 year) control of Atrial Fibrillation (AF)

- The effectiveness of a closed loop saline irrigated cooled tip ablation catheter
compared with standard 4-mm tip or 8-mm tip ablation catheter in achieving successful
electrical isolation of pulmonic vein(s).

Study participants shall have a 1:1 chance of getting either ablation of all 4 PVs vs. only
the PVs that are shown to start AF and also for creation of the radiofrequency ablations you
have 1:1 chance of being enrolled either in the arm that utilizes the standard catheter vs.
that which utilizes the saline irrigated cooled tip catheter. The duration of your
participation in the study will be for a maximum of 12 months. This trial is being conducted
in approximately 300 patients.

Hypothesis:

Total electrical isolation of all 4 PVs compared with electrical isolation of only PV(s)
where abnormal impulses are found should be more efficacious in achieving long-term cure of
patients undergoing ablation for AF. Furthermore, the saline irrigated cooled tip catheter
should be able to accomplish successful EI of PV(s) in either group with lesser number of
lesions when compared with the standard 4-mm tip or 8-mm tip ablation catheter.

Inclusion Criteria:

- All pts of age 40 years or over that are referred to our center for ablation of AF
and meet the clinical criteria to undergo the procedure shall be eligible to
participate in the study.

Exclusion Criteria:

- Failure to obtain informed consent

- Age < 40 years

Despite the reported low incidence of pulmonic vein stenosis (0.8%) as a potential
complication of PV isolation in pts undergoing AF ablation, in younger pts where it
appears that AF results mostly from foci from a limited number of PVs, we feel that
including them in the current study with a possibility of having all 4 PVs isolated cannot
be justified.