Cavotricuspid Isthmus Anatomy Determines The Success Of Remote Controlled Magnetic Bidirectional Block: A Comparsion Between Magnetic 8-mm Solid Tip And 3.5-mm Magnetic Irrigated Tip Catheter

BACKGROUND: Cavotricuspid isthmus (CTI) anatomy is associated with a great inter-individual variability. The aim of this study was to compare the magnetic 8-mm tip catheter versus the novel 3.5-mm magnetic irrigated tip catheter in achieving bidirectional right atrial isthmus block and to evaluate the impact of the underlying CTI anatomy on success rate. METHODS: A detailed remote controlled 3-dimensional electroanatomic (3D EA) right atrial reconstruction was performed using the magnetic navigation system with special emphasis to the CTI. CTI anatomy was evaluated utilizing the 3D EA map and classified into (A) simple (flat), (B) complex (pouch-like recess or concave shape) or (C) highly complex (pouch-like recess and concave shape). Patients were treated either with the magnetic 8-mm tip catheter (group I) or the open irrigated magnetic 3.5-mm tip catheter (group II). Primary endpoint was defined as acute bidirectional CTI block utilizing exclusively the remote controlled magnetic navigation system. Secondary endpoint was any procedure related complication and procedure time. RESULTS: In group I (n=10, 10 males, mean age: 65 ± 9 years) the primary endpoint was achieved in 80% (8/10 pts) requiring a median (Q1; Q3) RF application time of 37.1 min (22.8; 71.5) and a median (Q1;Q3) cumulative energy (CE) of 70.68 kJ (kilo Joule). (10.76;40.59). In group II (n=13, 10 males, mean age: 60 ± 7 years) the primary endpoint was achieved in 92 % (12/13) with a median (Q1; Q3) RF application time of 21.9 min (13.0; 27.0; p value=0.036) and a CE of 33.54 KJ (26.59; 49.22; p value=0.015). Variable CTI anatomy was identified for group I (type A: n=5 pts, type B: n=5 pts, type C: n=0 pts) and group for II (type A: n=4 pts, type B: n=7 pts, type C: n=2 pts). In group I magnetic ablation failure was associated with type B CTI anatomy (n=2 pts) and in group II with type C CTI (n=1). No procedure related complications were observed. CONCLUSION: Remote controlled catheter ablation of typical atrial flutter using the magnetic navigation system appears to be safe and feasible. CTI anatomy determines remote controlled magnetic ablation success. Use of the magnetic 3.5 mm irrigated tip catheter should be considered in patients with complex CTI anatomy.