Impact of catheter ablation of the coronary sinus on paroxysmal or persistent atrial fibrillation

Objectives: This study evaluated the impact of catheter ablation of the coronary sinus (CS) region during paroxysmal and persistent atrial fibrillation (AF). Background: The CS musculature and connections have been implicated in the genesis of atrial arrhythmias. Methods: Forty-five patients undergoing catheter ablation of AF were studied. The CS was targeted if AF persisted after ablation of pulmonary veins and selected left atrial tissue. CS ablation was commenced endocardially by dragging along the inferior paramitral left atrium. Ablation was continued from within the vessel (epicardial) if CS electrograms had cycle lengths shorter than that of the left atrial appendage. RF energy was limited to 35 W endocardially and 25 W epicardially. The impact of ablation was evaluated on CS electrogram cycle length (CSCL) and activation sequence, atrial fibrillatory cycle length measured in the left atrial appendage (AFCL) and on perpetuation of AF. Results: Endocardial ablation significantly prolonged CSCL by 17 +/- 5 msec and organized the CS activation sequence (from 13% of patients before to 51% after ablation); subsequent epicardial ablation further increased local CSCL by 32 +/- 27 msec (P < 0.001). AFCL prolonged significantly both during endocardial and epicardial ablation (median: 152 to 167 msec P = 0.03) and was associated with AF termination in 16 (35%) patients (46% of paroxysmal and 30% of persistent AF). AFCL prolongation >= 5 msec and/or AF termination was associated with more rapid activity in the CS region originally: P <= 0.04. Conclusion: Catheter ablation targeting both the endocardial and epicardial aspects of the CS region significantly prolongs fibrillatory cycle length and terminates AF persisting after PV isolation in 35% of patients.