Anatomic approach to mitral isthmus ablation guided by left atrial intracardiac echocardiography

Catheter ablation of mitral annular flutter is challenging, often requiring ablation in the coronary sinus or ethanol infusion into the vein of Marshall (VOM). Intracardiac echocardiography (ICE) from the left atrium provides unobstructed views of the mitral isthmus anatomy.

This study investigated the outcomes and safety of mitral isthmus ablation using a stepwise approach guided by left atrial ICE.

After transseptal access was achieved, the ICE catheter was advanced into the left atrium. Linear endocardial ablation was performed between the left inferior pulmonary vein and the mitral annulus, followed by coronary sinus ablation and VOM ethanol infusion if there was failure to achieve block. ICE was used to select the ablation plane, to monitor catheter contact, to titrate energy, and to assess lesion formation.

Thirty patients (age, 70 ± 9 years; 73% male) were included. The mean length of the mitral isthmus was 32.5 ± 5.4 mm, with a depth of 6.0 ± 2.9 mm and a mean thickness of 4.5 ± 0.5 mm. Bidirectional mitral isthmus block was achieved in 29 of 30 cases (97%), with epicardial ablation through the great cardiac vein required in 57% (n = 17 patients) and VOM ethanol infusion in 43% (n = 13 patients). Complications included 1 case of pericardial effusion (3%). During a follow-up of 19 ± 9 months, 13 patients experienced recurrent atrial arrhythmias, with a 12-month survival free of arrhythmias of 60%.

An anatomic approach to mitral isthmus ablation guided by left atrial ICE is feasible and safe, with high acute procedural success.