Efficacy of coronary sinus ablation for treatment of atrial fibrillation.

Pulmonary vein isolation, roofline and coronary sinus ablation Pulmonary vein isolation will be performed by positioning a circular mapping catheter sequentially at each pulmonary vein ostium, with location confirmed via fluoroscopy and virtual 3D navigation. Pulmonary vein isolation will be defined as abolition or dissociation of pulmonary vein potentials on a circumferential mapping catheter positioned at the ostium of the vein. All veins will be individually isolated via this technique. Common ostia venous architecture will be isolated en bloc with circumferential ablation and confirmation of electrical disconnection by positioning of the Lasso catheter within each of the inferior and superior branches. The permanence of electrical disconnection (ie. ablation line continuity) will be verified at least 30 minutes after the last ablation at that vein. Roofline ablation will be performed in a continuous motion from the left superior pulmonary vein ostium to the right superior vein ostium as defined by fluoroscopy and 3D navigation. To maintain atrial wall contact, the ablation catheter will be looped within the atrium so that superior torque (ie. pressure on the roof) can be maintained throughout a continuous burn. Ablation of the coronary sinus musculature and left atrium will be performed both endo- and epicardially through the coronary sinus in an attempt to electrically disconnect (ie. isolate) this structure from the left atrium. For the endocardial approach, the ablation catheter will be dragged along the endocardium of the inferior left atrium after looping the catheter in such a way as to position it parallel to the coronary sinus catheter. The ablation endpoint will be elimination of local endocardial electrograms bordering the mitral annulus. Ablation within the coronary sinus will be performed by starting distally (4 o’clock in the left anterior oblique position) and continuously dragged to the ostium, where the coronary sinus empties into the right atrium. Additional point ablation will be performed around the coronary sinus (CS) orifice from the right atrium to ensure its electrical disconnection from the atrial myocardium. The endpoint of epicardial ablation will be the electrical isolation (as represented by the abolition or dissociation of electrograms in the coronary sinus catheter) of the coronary sinus. Total procedure duration should be 3-4 hours, inclusive of the time required to isolate the coronary sinus (30 mins).