Abstract 2319: Mapping and Radiofrequency Catheter Ablation of the Marshall Bundle in the Treatment of Persistent Atrial Fibrillation
Background: Previous studies showed that complex fractionated atrial electrogram (CFAE) is often present in the Marshall bundle (MB) during persistent atrial fibrillation (AF), suggesting that MB is highly arrhythmogenic. We hypothesize that electrophysiological mapping followed by radiofrequency catheter ablation (RFCA) of the MB can reduce the incidence of post-ablation left atrial flutter (LAFL).
Methods: We performed MB mapping and RFCA in 72 consecutive patients (pts) (59 men, 59.9±9.4 years old) with persistent AF. The control group included 72 pts who underwent RFCA without MB mapping.
Results: Successful MB mapping was completed in 64 (89%) pts. The endocardial approach (vein of Marshall cannulation) was performed in 21, the epicardial approach in 34 and combined approach in 9 pts. There were 3 types of MB-left atrium (LA) connections.
Single connection (at coronary sinus) was noted in 11 pts. The MB recordings exhibited distinct double potentials during sinus rhythm. During AF, MB activity may be dissociated with left atrium (LA) activations.
Double connections (with MB connecting to coronary sinus and also to the left pulmonary veins) were noted in 23 pts. After the ablation of distal connection, the MB recording exhibited typical double potentials as in single connection.
Multiple connections were noted in 30 patients.
During sinus rhythm, the earliest activation was in the middle of the MB but the propagation patterns were highly variable among different patients. CFAE was noted during AF in all patients of the third group. RFCA disconnected the MB potential in all 64 patients. After 24 months of follow up, repeat ablation was needed in 30 patients in the control group and 20 in MB mapping group (P=NS). Sinus rhythm was documented in 54 pts of control group and 61 pts of MB mapping group (P=NS). Post-ablation LAFL occurred in 8 pts in MB ablation group and 18 in control group (P=0.03).
Conclusions: Three types of MB-Single, dual or multiple connections were present between MB and LA in pts with persistent AF. RFCA procedures that included MB disconnection significantly reduced the incidence of post-ablation LAFL and were associated with high incidence of long term success.