Interim analysis: no statistically significant difference in the 2 study arms.

In this randomized double-blind study, the investigators would like to compare standard practice (i.e., use of luminal esophageal temperature monitoring) to that of esophageal deviation during AF ablation. The investigators hypothesize that the strategy of esophageal deviation will result in safer ablation strategy with a reduction in the incidence of esophageal injury as assessed by endoscopy.

Catheter ablation is a commonly performed strategy employed for the treatment of atrial fibrillation. However ablation in the posterior wall of the left atrium can cause thermal injury to the esophagus. When significant thermal injury to the esophagus occurs, two significant complications can occur: 1) the formation of an atrio-esophageal fistula, and 2) gastrointestinal dysmotility. While the former is rate, it is an important complication since it can be fatal. The frequency of the latter complication is less well appreciated, but probably occurs in the range of 1:100 to 1:500. Currently luminal esophageal temperature monitoring is the most commonly employed modality to prevent such injury. However, there are limitations to its use, and atrio-esophageal fistulas have been reported even when using esophageal temperature monitoring. Esophageal deviation using either a TEE or EGD probe has been described in the literature, but the effectiveness and practicality of these techniques are suboptimal, and have therefore precluded their use in routine clinical practice. Recently, we have demonstrated that esophageal deviation is indeed possible using off-the-shelf equipment (a soft thoracic tube and endotracheal stylet) in patients undergoing AF ablation. In this randomized double-blind study, we will compare standard practice (i.e., use of luminal esophageal temperature monitoring) to esophageal deviation during AF ablation. We hypothesize that the strategy of esophageal deviation will result in safer ablation strategy with a reduction in the incidence of esophageal injury as assessed by endoscopy.

Inclusion Criteria:

• Age >18 - Age < 80 yr
• Documentation of atrial fibrillation (AF)
• Referred for a first ever ablation procedure for AF (prior ablation of right-sided Typical flutter, or "limited" left-sided of an accessory pathway are permitted)
• General anesthesia
• All patients must understand and adhere to the requirements of the study and be willing to comply with the post study follow-up requirements.

Exclusion Criteria:

• Any reversible cause of AF (post-surgery, thyroid disorder, etc.)
• INR > 4.0 at the time of the procedure
• H/o of severe esophageal ulcers, strictures, esophagitis or GERD
• H/o Esophageal Surgery
• Prior surgical or catheter ablation procedure for AF (except right atrial flutter ablation)
• Any evidence of esophageal diverticulum or other structural abnormalities of the esophagus seen during baseline barium esophagogram
• Significant abnormality on Swallowing Impairment Score
• Mental impairment precluding signing consent or completing follow up
• Patients with any other significant uncontrolled or unstable medical condition
• Women who are known to be pregnant or have had a positive β-HCG test 7 days prior to procedure

17 roll-in patients and two pre-procedure withdrawals are removed from the analysis

17 roll-in patients and two pre-procedure withdrawals are removed from the analysis.