Effect of Balloon Cryoablation on Left Atrial Function (CRYO-LA)

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

cryoablation, recurring arrhythmia, stroke, RF ablation, LA ablation, nodal ablation, catheter ablation

For each patient, the balloon catheter will be advanced to the ostium of each pulmonary vein. Once location has been optimized, the balloon will be inflated, and cryoenergy delivery will be initiated. Because the entire surface of the balloon acts as an ablative surface, circumferential ablation of each pulmonary vein will be achieved concurrently. This will be completed for each pulmonary vein for each patient.

Acute Procedural Success (APS) is the demonstration of electrical isolation of all 4 PVs or their anomalous equivalents at the conclusion of the first protocol-defined cryoablation procedure.

Number of Participants with AF Recurrence at 6 months and at 12 months after Cryoballoon Ablation for Atrial Fibrillation. (Chronic Treatment Success is defined as a subject who does not have episodes of AF, lasting at least 30 seconds in duration, 3 months following the initial ablation procedure.)

Transthoracic Echo Assessment of Left Atrial Function at Baseline and 6-Months Post- Cryoballoon Ablation for AF Parameters of atrial function: Volumes at P-wave onset and end-systole LA active emptying volume LA active emptying fraction Late diastolic peak velocity LA filling fraction Pulmonary venous inflow pattern

Ventricular Function measured by Left Ventricular Ejection Function (LVEF). A normal left ventricular ejection fraction (LVEF) ranges from 55% to 70%. An LVEF of 65%, for example means that 65% of total amount of blood in the left ventricle is pumped out with each heartbeat.

Transthoracic Echo Assessment of Left Atrial Function at Baseline and 6-Months Post- Cryoballoon Ablation for AF

Transthoracic Echo Assessment of Left Atrial Function at Baseline and 6-Months Post- Cryoballoon Ablation for AF Deflections of the mitral annulus as measured by peak early ventricular diastolic velocity (E'), and during atrial contraction (A')

Chronic Treatment Success for the follow-up visit within treatment windows. 1. Whether on or off Atrial Fibrillation Drugs (AFDs) during the Non-blanked Follow-up Period 2. When off Atrial Fibrillation Drugs

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.

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