This study is to investigate the correlation and to obtain the coefficient of correlation between the global and local bipolar signals (voltage maps) of the LA in sinus rhythm using a focal 4.5 mm irrigated-tip ablation catheter (in combination with microelectrodes), a ring-electrode circular mapping catheter and a microelectrode multipolar catheter in combination with the Rhythmia system.

Current hypothesis of the mechanism of atrial fibrillation (AF) is a combination of local firing mainly triggered from the pulmonary veins and atrial substrate due to atrial remodelling sustaining AF. Whereas for paroxysmal AF, pulmonary vein isolation (PVI) is still the mainstay of interventional treatment, a left atrial (LA) substrate-based ablation especially in patients with persistent or long-standing persistent AF may be reasonable to improve freedom from AF. In addition, even in patients with paroxysmal AF, substrate-based ablation strategies have been shown to improve outcome. Substrate characterization of the LA is currently performed using the focal ablation catheter with a 3.5mm irrigated tip catheter with a 2 mm interelectrode spacing, a circular (Lasso) or spider like diagnostic (Pentaray) catheter with 1 mm size of the ring electrodes and 2 mm to 4 mm interelectrode spacing. Consequently, the cut-off values to delineate healthy tissue from diseased substrate are defined based on these measures. Since the electrode size and distance between the electrodes determines the bipolar voltage amplitude and morphology (beside their orientation with regard to the propagation wavefront), differences in bipolar voltage values must be expected between different catheter types and especially for the novel micro-electrode catheters IntellaMap Orion and IntellaNav MIFI OI. With the knowledge of the relationship between the bipolar voltage maps created with the different catheter types, information/knowledge from one study obtained with a specific catheter can be transferred to patients treated with the other catheter types. This study is to investigate the correlation and to obtain the coefficient of correlation between the global and local bipolar signals (voltage maps) of the LA in sinus rhythm using a focal 4.5 mm irrigated-tip ablation catheter (in combination with microelectrodes), a ring-electrode circular mapping catheter and a microelectrode multipolar catheter in combination with the Rhythmia system.

Inclusion Criteria:

• Documented atrial fibrillation
• First or repeat catheter ablation

Exclusion Criteria:

• Previous heart surgery (high probability for atypical atrial tachycardia and non PV triggers for AF)
• Congenital heart disease (corrected or uncorrected)
• Severe uncorrected valvular heart disease
• Not willing or qualified for Magnetic Resonance Imaging of the heart
• Unable to provide informed consent
• Pregnancy (Pregnancy test will be performed before study participation)
• Patients with pacemaker or intracardiac defibrillator implanted

Patients undergoing catheter ablation for atrial fibrillation at the University Hospital Basel