The purpose of this study is to compare rotational angiography (3DATG technology)intra-procedure (during the ablation procedure) with CT (x-ray) pre-procedure (before the ablation procedure) fusion to create an anatomical picture of a heart to help adequately guide an ablation procedure for patients with arrhythmias.

Rotational angiography (or three dimensional arteriography or "3DATG") is a new tool used to guide atrial fibrillation (AF) ablation. The current approach to imaging for AF ablation involves obtaining a computer tomography (CT) angiogram of the atrium pre-procedure and combining it with an electro-anatomical map, a process called merging or overlay. The investigators propose to investigate the quality of the 3DATG as a replacement for the CT in obtaining a left atrial angiogram (to guide AF ablation).

All imaging modalities to be evaluated in this study are currently used in clinical practice. They are not experimental methods. The goal is to compare two modalities that have never been directly compared before. The CT angiography utilizes a standard CT scanner and intravenously injected contrast agent to visualize the left atrium. While the 3DATG is a method that achieves similar results to a CT scanner, the difference is that the 3DATG images are acquired by rotating the X-ray source around the patient on a C-arm instead of a dedicated CT scanner.

60 participants will be consented and randomized to either pre-procedure CT or intra-procedure 3DATG. Scheduled participants will undergo sedation and catheter instrumentation as appropriate. CT anatomy data will then be merged with the live X-ray via the EP Navigator system in standard fashion or the patient will be prepped for appropriate 3DATG anatomy data acquisition and merged with the EP Navigator system. The EP Navigator system will then be used to send either data to NavX or CARTO to create the intended electro-anatomical map.

Using the CT or 3DATG acquired electro-anatomical map, the ablation procedure will be conducted in the same way as would the local practice and standard of care for any patient not participating in the study.

The ablation procedure and the sites of ablation lesions will be tagged on the 3D overlaid anatomy in the same fashion as previously published and all participants will be followed as routine at a 1 month and 3 month follow up.

Inclusion Criteria:

• All patients undergoing a clinically indicated left-sided ablation procedure for atrial fibrillation

Exclusion Criteria:

• Patients not willing or able to provide consent to participate or already involved in another clinical trial.

All patients undergoing a clinically indicated left-sided ablation procedure for atrial fibrillation who therefore satisfy conventional criteria for catheter ablation.