Alternative strategies to improve success rate of mitral isthmus block

Abstract

Achieving bidirectional conduction block (BDB) across the mitral isthmus (MI) is technically challenging. We describe our experience using different ablation strategies for achieving successful MI block.We reviewed the records of patients who had undergone MI ablation for peri-mitral (PM) flutter at our institution from January 2010 to May 2015. We investigated ablation strategies for achieving MI block and their long-term outcomes in terms of recurrence of atrial tachyarrhythmia.Single endocardial MI ablation with or without distal coronary sinus (CS) ablation achieved MI block in 129 out of 236 (54.7%) patients. After failure of MI block, a new MI line ablation, ablation targeting the vein of Marshall (VOM), or anterior line ablation was performed in selected patients. The MI block was achieved in 13 (52.0%) out of 25 patients with new MI line ablation and in 13 (68.4%) out of 19 patients with VOM ablation. Anterior line ablation was tried in 23 patients and the line of block was achieved in 12 (52.2%) patients. Finally, overall PM BDB (PMB, MI block or anterior line block) was achieved in 167 (70.8%) of 236 patients. The incidence atrial tachyarrhythmia was similar between the patients with successful PMB and those with failed PMB (32.9% vs 42.0%, P = .18). In multivariable Cox regression analysis, the PMB was not associated with recurrence of atrial tachyarrhythmia (hazard ratio [HR]: 0.70, 95% confidence interval [CI]: 0.43–1.12).In conclusion, single endocardial MI line with or without distal CS ablation showed limited success for achieving MI block. Additional substrate modifications such as a new MI line ablation, anterior line ablation, or ablation targeting the VOM may improve the success rate of PMB block. However, the benefits of PMB were not clear in this study.

Comparison of the empirical linear ablation and low voltage area-guided ablation in addition to pulmonary vein isolation in patients with persistent atrial fibrillation: a propensity score-matched analysis

“…Compared to the previous studies evaluating outcomes of the lateral MVI line ablation and/or anterior and vein of Marshall ablation [ 8 , 9 , 20 ], we successfully confirmed bidirectional block of almost all linear ablations during the first session (MVI, 96.9%; roof line, 100%). This is probably due to the fact that a considerable amount of time and RF energy was used to archive to complete the block line; however, recurrence of linear lesions was proven to some extent in the second session.…”

“…Among them, linear ablation attempts to modify the left atrium (LA) as a conventional approach with proven efficacy [ 7 ]. However, creating complete (and durable) conduction block along a linear lesion is sometimes challenging [ 8 ]. In particular, ablation of the mitral valve isthmus (MVI) was achieved in 75% of patients in the Star AF II study, a large-scale randomized study [ 9 ], and the authors concluded that there was no reduction in AF recurrence when either linear ablation or CFAE ablation was performed in addition to PVI.…”

Thermal impact of balloon occlusion of the coronary sinus during mitral isthmus radiofrequency ablation: an in-silico study

“…It is currently accepted that the creation of contiguous and transmural linear lesions across the mitral isthmus is technically challenging and may be associated with significant complications [28]. Since extensive ablation on the mitral isthmus can cause serious complications, including cardiac tamponade, circumflex artery occlusion, and atrio-esophageal fistula [29,30], increasing the RF power and ablation duration should be performed very carefully because of the increased risk of complications [31]. For this reason alternative strategies may be explored to overcome certain anatomic limitations and achieve durable mitral isthmus block, such as cryoablation [32], ethanol infusion into the vein of Marshall [33], and temporary occlusion of coronary sinus blood flow [34,35].…”

Esophageal Thermal Injury after Catheter Ablation for Atrial Fibrillation with High-Power (50 Watts) Radiofrequency Energy

“…Venous access and catheterization were performed as previously described. 11) Transseptal catheterization was performed under the guidance of hemodynamic monitoring, fluoroscopy, and intracardiac echocardiography (SOUNDSTAR catheter; Biosense Webster, Diamond Bar, CA, USA). Two 8 Fr SL1 sheaths (St. Jude Medical, St. Paul, MN, USA) were advanced into LA to handle a mapping catheter and an ablation catheter, respectively.…”