Comparison of the anterior and posterior mitral isthmus ablation lines in patients with perimitral annulus flutter or persistent atrial fibrillation.

BACKGROUND: Catheter ablation of left atrial linear lesions is an effective treatment option for perimitral flutter and is often used as a substrate modification approach for persistent atrial fibrillation. The two most popular mitral isthmus lines are those of the anterior or the posterior mitral isthmus. A comparison of these two mitral isthmus ablation approaches is still pending.
METHODS: Patients undergoing catheter ablation either at the anterior or the posterior mitral isthmus were included. Procedural success, conduction block, procedure durations, complications, and the necessity of a coronary sinus ablation were analyzed.
RESULTS: We investigated 80 consecutive patients, 40 (50%) with an anterior and 40 (50%) with a posterior mitral isthmus line. Twenty (25.0%) patients had perimitral annulus flutter; the remainder of the patients had persistent atrial fibrillation. Bidirectional conduction block was achieved in the same proportion in the anterior group (36; 90.0%) as it was in the posterior group (30; 75.0%) (statistically insignificant). Duration of procedure (18 ± 12 vs. 34 ± 24 min, p = 0.001), radiofrequency application (11 ± 7 vs. 18 ± 11 min, p = 0.004), and fluoroscopy (2 ± 2 vs. 8 ± 8 min, p < 0.001) values were all significantly lower in the anterior group. Only patients in the posterior line group had to be ablated via the coronary sinus 24 (60.0 %).
CONCLUSIONS: Ablation at the anterior mitral isthmus shows the same success rate as the posterior mitral isthmus does. Catheter ablation at the anterior mitral isthmus is associated with significantly shorter procedure durations without the need of a coronary sinus ablation.