Use of Dabigatran Etexilate to Prevent Stroke and Thromboembolism

• Frequency of major bleeding complications and thrombo-embolic events in patients administered dabigatran following RF ablation. [ Time Frame: Within 4 months following procedure (+/- 4 days) ] [ Designated as safety issue: Yes ]
  

• Dabigatran serum drug levels in patients experiencing a major bleeding or thrombo-embolic event. [ Time Frame: Within 4 months following procedure (+/- 4 days) ] [ Designated as safety issue: Yes ]
  
• Frequency of minor bleeding events [ Time Frame: Within 4 months following procedure (+/- 4 days) ] [ Designated as safety issue: Yes ]
  

Study design

Approximately 100 patients who plan to have pulmonary vein isolation by antral radiofrequency or cryoablation for paroxysmal or persistent atrial fibrillation, or left atrial flutter following prior left atrial ablation procedures, with CHADS2 score of 0-6 or CHADS2-VASc score 0-9 will be eligible for this trial and enrolled. A transesophageal echocardiogram (TEE) will be performed pre-procedure based on the presenting cardiac rhythm the day of planned catheter ablation, stroke risk by CHADS2 or CHADS2-VASc score, and preceding use of therapeutic anti-coagulation (as per current 2012 HRS/ACC/ESC guidelines on atrial fibrillation management). Immediately following the ablation procedure (4-6 hours after sheath pull and vascular hemostasis), dabigatran etexilate 150mg bid, or 75mg twice daily based on creatinine clearance in the Use in Specified Populations (USPI), will be administered for a minimum of 3 months post RF ablation. This represents the standard blanking period for post atrial fibrillation or left atrial flutter catheter ablation anticoagulation therapy. After the 3 months blanking period, patients may safely be taken off dabigatran in the low risk group for stroke or thromboembolism, according to the investigators discretion (CHADS 2 score 0-1, or CHADS2-VASc score 0-1). If on dabigatran etexilate pre-procedure, the drug will be held at least 24 hours before the intervention depending on renal function of the patient (as per recommendations in the USPI). If possible, discontinue dabigatran 1 to 2 days (CrCl >50 mL/min) or 3 to 5 days (CrCl <50 mL/min) before an invasive or surgical procedure, due to increased risk of bleeding.

Dabigatran etexilate will be resumed 4-6 hours after sheath pull and vascular hemostasis post ablation as above. Intra-procedure intravenous heparin drip will be started once left atrial access is obtained with an ACT goal target 300-350 seconds by weight based nomogram. Standardized ablation endpoints (4 vein entrance and exit block with post ablation adenosine challenge and/or isoproterenol, or termination of left atrial flutter and completion of linear ablation confirmed by differential pacing) will be documented, along with radiofrequency or cryoablation

delivery time, fluoroscopy and total case time. Inpatient adverse events will be documented, and outpatient follow up will occur at 1 and 3 months post ablation per standard protocol, with documentation of all composite endpoints (see below). In addition, a 30 day post study phone call follow up will be performed (30 days +/- 4 days following the 3 month visit). Please see Table 1 for the schedule of events.

Our hypothesis is that exposure to dabigatran in the setting of AF left atrial catheter ablation will be associated with alow or acceptable risk of major adverse bleeding risks, and low thromboembolic event rates post RF ablation, in accordance with our previous data, and in contrary to the findings of Lakireddy, et al, in their retrospective study published 2012 in JACC. This could lead to widespread utilization of dabigatran etexilate for centers performing a high number of atrial fibrillation and left atrial flutter ablation procedures.