Catheter ablation has emerged as an effective therapy for atrial fibrillation (AF). However, achievement of complete& durable isolation of the pulmonary veins (PVs) is challenging, primary limited both by operator experience and also the limits of currently available ablation technology. Direct contact force sensing (CFS) is a novel technology that may help to ensure adequate lesion delivery. CFS may also help to improve the safety profile of catheter ablation. The purpose of this study is to compare two strategies of wide antral PV isolation plus linear ablation for persistent AF:

1. guided by contact force sensing (CFS) OR
2. blinded to contact force sensing (CFS) - i.e. standard approach

Inclusion Criteria

• Age > 18 years.
• Patients undergoing first-time catheter ablation for AF.
• Persistent AF defined as episodes greater than 7 days duration.
• Symptomatic AF defined as patients who have been aware of their AF anytime within the last 5 years prior to enrolment. Symptoms may include, but are not restricted to, palpitations, shortness of breath, chest pain, fatigue, left ventricular dysfunction, or other symptoms, or any combination of the above.
• At least one episode of AF must have been documented by ECG, Holter, loop recorder, telemetry, implanted device, or transtelephonic monitoring within 24 months of enrolment.
• Willing and able to provide informed consent.

Exclusion Criteria

• Paroxysmal AF.
• AF secondary to a reversible cause.
• Patients with contraindications to systemic anticoagulation with heparin, coumadin, or a direct thrombin inhibitor.
• Patients who have previously undergone AF ablation.
• Patients with left atrial size >55 mm (echocardiography, parasternal long axis view).
• Patients who are or may potentially be pregnant.