Six-month follow-up of isthmus-dependent right atrial flutter ablation using a remote magnetic catheter navigation system: a case-control study

Objective - The objective of this study was to compare results between the magnetic navigation system (MNS) and conventional catheter ablation of cavo-tricuspid isthmus (CTI)-dependent right atrial flutter (AFL) in a case control study. Background - A remote MNS has been used for ablation of various arrhythmias including CTI-dependent AFL but comparative results between MNS and conventional ablation are not available. Methods - Between May and September 2007, a total of 51 consecutive patients (45 men, mean age 65.4+/-9.4 years) had undergone catheter ablation for CTI-dependent AFL. The catheter ablation (70 degrees C, 70W, 90 s) was performed with either an 8-mm-tip magnetic catheter using MNS (case group, n=26, 23 men, mean age 64.6+/-9.6 y) or a conventional 8-mm catheter (case group, n=25, 22 men, mean age 65.4+/-9.1 y). Acute procedural success was defined as complete bidirectional isthmus block and success at six months was defined as absence of AFL during the six months follow-up. Results - With respect to baseline characteristics there were no differences between the two groups. The procedure time in MNS and conventional group was [median (range)] 53 (30-130) min and 45 (30-100) min, respectively (P=0.12). Acute success was achieved by MNS and conventional ablation in 25/26 (96.2%) and 25/25 (100%) of patients, respectively (P=0.53). During the six months of follow-up 4 patients, 2 in each group, experienced recurrence (P=0.90). No major complication occurred during the procedure. Charring on the catheter tip occurred in 5 patients (19.2%) in MNS and none of the patients in the control group (P < 0.05). Conclusion - This case-control study demonstrated the acute and mid-term efficacy and safety of catheter ablation by MNS for CTI-dependent AFL, similar to rates achieved by conventional radiofrequency catheter ablation.