Abstract 3227: Comparison of Externally Irrigated versus Standard Eight Millimeter Tip Catheters for Achieving Bidirectional Mitral Isthmus Block During Left Atrial Linear Ablation for Atrial Fibrillation
Background: Achieving bidirectional mitral isthmus (MIB) block may reduce incidence of post-ablation atypical atrial flutters (AAFL) and may increase overall success rate of ablation for atrial fibrillation (AF).
Objective: To determine if there is any difference between the ThermoCool® catheter and standard 8 mm tip catheters for achieving MIB and whether the type of catheter affects the occurrence of post-ablation AAFL or AF recurrence.
Methods and Results: Fifty-three consecutive patients (pts), mean age 59 ± 8 years, who underwent linear ablation for symptomatic, persistent or paroxysmal AF were evaluated. All patients underwent left atrial linear ablation (LALA) with two encircling lesions around the right and left pulmonary veins, a line at the roof of the left atrium between the two circles, and a line from the mitral valve annulus to the left circle (with or without adjunctive coronary sinus ablation) with the goal of achieving MIB. Bi-directional MIB was documented by pacing from the left atrial appendage and proximal coronary sinus. MIB was achieved in 35 pts (66%), with ablation in the coronary sinus required in 85.3% of pts. Thirty-seven pts underwent LALA with a standard 8 mm tip (Blazer™ or Navistar™) catheter and 16 pts underwent ablation with an externally irrigated (ThermoCool™) catheter. MIB was achieved in 65% of pts in the 8 mm tip group compared to 69% in the externally irrigated group. (p=0.78). Patients were followed for 6 ± 2 months, 26% had occurrence of AAFL, and 31% had recurrence of AF. In pts with AAFL, there was a marginal association between outcome and type of the catheter used, after controlling for age, gender and MIB (p=0.06), with a lower incidence of AAFL in the ThermoCool® catheter group (12.5%) compared to the 8 mm tip catheter group (32.4%). The type of catheter was not predictive of recurrence of AF after adjusting for age, gender and MIB (p=0.44), with recurrence of AF in 37% in the ThermoCool® catheter group and 27% in the 8 mm tip catheter group.
There was no significant difference in the success of achieving MIB with externally irrigated vs. standard 8 mm tip catheters.
There was a trend towards a lower incidence of AAFL during follow-up with the externally irrigated catheter vs. standard 8 mm tip catheters.