Abstract 14132: Importance of Confirmation of Mitral Isthmus Block During Ablation of Persistent Atrial Fibrillation
Introduction: Linear lesions across the posterior mitral isthmus (PMI) have been shown to increase the success rate of catheter ablation (CA) of persistent AF. However, PMI ablation often requires extensive ablation to achieve bidirectional conduction block (BCB) which may increase complication rates.
Methods: We compared two groups of consecutive patients who underwent their first CA for persistent AF. All patients underwent wide area circumferential ablation to achieve pulmonary vein isolation with supplemental left atrial roof and PMI linear lesions. In group 1 (n=36), empiric endocardial (EC) ablation of the PMI was performed, with no coronary sinus (CS) ablation or confirmation of BCB. In group 2 (n=77), PMI ablation was performed until BCB was confirmed, ablating from the EC and within the CS if necessary. Post-ablation testing on isoproterenol was performed in all patients and extra-PV triggers were mapped and ablated when present.
Results: There was no difference in baseline patient characteristics between the two groups. Comparing group I and 2, fluoroscopy (68.2 +/- 4.7 min vs 53.6 +/- 3.1 min, p<0.01) and procedure (6.0 +/- 0.4 hr vs 5.2 +/- 0.2 hr, p<0.01) times were significantly lower in group 2. Extra-PV triggers were present in 58% and 52% of groups 1 and 2, respectively (p=0.55). For group 2, 86% required ablation within the CS to achieve BCB. Serious complications included one moderate pericardial effusion and one retroperitoneal hematoma in group 1 and one patient with tamponade in group 2. AF recurrence rates at 1 year were 38.8% and 19.7% in groups 1 and 2 (p=0.06). Repeat AF ablation within one year occurred in 11/36 (30.5%) and 5/77 (6.58%) in groups 1 and 2 (p<0.01).
Conclusions: Confirmation of PMI BCB was associated with a trend toward lower recurrence rates and a significant reduction in short-term repeat ablations. This may reflect a decrease in potentially proarrhythmic substrate when linear lesion sets are made complete. Major complications did not significantly increase, while procedural and fluoroscopy times were paradoxically lower when PMI block was achieved with extensive ablation.
- © 2011 by American Heart Association, Inc.