Effect of Mitral Isthmus Block on Development of Atrial Tachycardia Following Ablation for Atrial Fibrillation

Abstract

AT occurring after CPVA plus LALA is often due to incomplete MI ablation, but may also occur at the LA roof, and ridge between the LA appendage and left PVs. Failure to achieve MI block increases the risk of developing AT. Resumption of MI conduction may also be a mechanism for AT recurrence. (PACE 2010; 460-468).

Circumferential Pulmonary Vein Ablation With Additional Linear Ablation Results in an Increased Incidence of Left Atrial Flutter Compared With Segmental Pulmonary Vein Isolation as an Initial Approach to Ablation of Paroxysmal Atrial Fibrillation

“…10,11 Like the MI, it is likely that the complex anatomy in this region, along with difficulty stabilizing the catheter along this ridge during radiofrequency catheter ablation, may explain why macroreentrant atrial tachycardias may arise from this region from gaps that arise after ablation, despite initial documentation of PVI. 12 Our results differ from those published by Oral et al, 13 who reported better success rates with CPVAϩLALA at the MI and posterior LA as compared with segmental PVI. A major difference between our study and that published by Oral et al is that we observed a 24% incidence of LAFL when using a similar CPVAϩLALA approach, which is significantly higher than the 2.5% incidence reported in that study.…”

Balloon occlusion of the distal coronary sinus facilitates mitral isthmus ablation

“…[1][2][3]5,7,8,[15][16][17][18][19][20] Previous studies 9,21,22 have suggested that anatomical features such as myocardial thickness, long isthmus length, morphology, and recesses or crevices were possible obstacles to mitral isthmus ablation. These features are not significantly different from those of the cavotricuspid isthmus and should be overcome by the use of modern irrigated-tip catheters.…”

Recovery of Mitral Isthmus Conduction Leads to the Development of Macro-Reentrant Tachycardia After Left Atrial Linear Ablation for Atrial Fibrillation

“…Studies have shown that even with endocardial and epicardial ablation, MI block may only be achieved in 82% to 89% of cases, and failure to achieve bidirectional MI conduction block results in an increased rate of recurrence of MIdependent LAT. 5,10 However, recovery of conduction has also been noted in some studies 10,11 but has not been well-characterized. By excluding patients in whom MI block could not be achieved at initial ablation, we were able to demonstrate that recovery of conduction across the MI is common and also correlates with the development of MIdependent LAT.…”

“…I, aVF, and V1 indicates surface ECG leads; RFd&p, proximal and distal electrodes on the RF catheter positioned at the His bundle in A and at the lateral cavo-tricuspid isthmus in B; CSp-d, proximal to distal coronary sinus electrograms; PVd-p, proximal to distal electrograms on the PV loop catheter (Lassoா); S, stimulus artifact. Adapted with permission from Anousheh et al 10 remaining 2 patients (transisthmus conductions times Ͻ120 ms). Recurrent MI conduction was predominately epicardial, requiring coronary sinus ablation in 33 of the 38 patients to achieve bidirectional block.…”