Effect of Balloon Cryoablation on Left Atrial Function

Atrial fibrillation is a common and disabling irregular heart rhythm, that affects 1 to 1.5 million Americans. Recent clinical experience with the Medtronic Arctic Front™ Cardiac CryoAblation Catheter System suggests that it can be used to isolate the pulmonary veins (PVs) safely and effectively in patients with AF, thereby reducing or eliminating the recurrence of AF.3-4 However, the very large ablative surface of this balloon ablation catheter raises the possibility that this technique may damage extensive areas of the atrial myocardium.

The LA is an elastic chamber, designed to expand and contract with ease to accommodate the influx and outflow of blood, while maintaining relatively low pressure. When exposed to stress or injury, whether acute or chronic, the LA may lose much of its elasticity, resulting in overall dilation accompanied by fibrosis in some cases. Overall, this may potentially result in diminution of LA mechanical function (both systolic contractile function, and diastolic relaxation function). In addition, LA function is linked to both Left Ventricular (LV) systolic and diastolic function, manifesting in an overall impact on cardiac remodeling, including the area of the pulmonary vein ostia, and a significant decrease in LV ejection fraction (LVEF). On the other hand, the positive effects of maintaining sinus rhythm with successful catheter ablation of AF may result in improvement of LA mechanical function.5-9

Based on the potentially deleterious effects of damage caused by cryoablation, to the atrial myocardium during balloon ablation, this prospective, non-randomized, single-center study has been designed to assess the atrial effects of balloon cryo-ablation.

This study is a prospective, non-randomized, single-center, controlled study of patients with AF referred for ablation after failing one or more Class I-IV antiarrhythmic drugs used in the treatment of AF.

• All study subjects will undergo cryoablation.

Subjects will be followed for 12 months to assess the chronic impact of ablation with the Medtronic CryoCath Arctic Front™ Cardiac CryoAblation Catheter System on LA and LV mechanical function. In addition, patients will undergo scheduled and symptom-driven assessments to detect recurrent AF and adverse events (AEs).

We will evaluate the effect of ablation with the Medtronic Arctic Front™ Cardiac CryoAblation Catheter System on the atrial myocardium, with respect to LA (and LV) mechanical function, by assessing images acquired using TTE and CT in adult patients with atrial fibrillation who have failed at least one anti-arrhythmic drug. The efficacy of the Arctic Front™ Cardiac CryoAblation Catheter System will be assessed by ambulatory continuous ECG monitoring

Eligibility Criteria:
Inclusion Criteria:

* Documented paroxysmal atrial fibrillation
* ≥ 18 and ≤ 85 years of age
* Failure of one or more AF Drugs (AFDs).
* Referral for a pulmonary vein isolation catheter ablation procedure to treat atrial fibrillation
* Ability to understand the requirements of the study
* Willingness to adhere to study restrictions and comply with all post- procedural follow-up requirements

Exclusion Criteria:

* Any reversible cause of AF (post-surgery, thyroid disorder, etc.)
* More than 4 cardioversions in the prior year.
* Patients with recent myocardial infarction (less than 2 months) or unstable angina.
* Patients with congestive heart failure (NYHA class III or IV).
* Patients who have experienced any cerebral ischemic event, including any TIA in the preceding 1 month.
* Women who are known to be pregnant or have had a positive β-HCG test 7 days prior to procedure.
* Patients with any other significant uncontrolled or unstable medical condition (including uncontrolled clinically significant coagulation disorders).
* Patients whose life expectancy is less than one year.