Posterior Left Atrial Isolation Research Articles

Posterior left atrial isolation is associated with a lower incidence of atrial tachycardia in patients with persistent atrial fibrillation.

Patients may develop atrial tachycardia (AT) after left atrial (LA) ablation of persistent atrial fibrillation (AF). The population consisted of 101 consecutive patients (age = 64.3 ± 8.7years, 70 males (69%), LA = 4.6 ± 0.8cm, ejection fraction = 48.5 ± 16%) undergoing their initial procedure for persistent AF. After pulmonary vein isolation, patients either underwent posterior LA isolation (n = 50; study group) or linear ablation at the LA roof with verification of conduction block (n = 51; control group). A repeat procedure was performed in 17 (34%) and 28 (55%) patients in the study and control groups, respectively (p = 0.02). Patients in the study group were less likely to develop AT (9/50 [18%] vs. 18/51 [35%]; p = 0.02), roof-dependent (1/50 [2%] vs. 8/51 [16%]; p = 0.008), and multi-loop AT (6/50 [12%] vs. 14/51 [27%]; p = 0.03) as compared to controls. Among various factors, only posterior LA isolation was associated with a lower likelihood of AT recurrence and roof tachycardia at redo procedure (OR, 0.37; 95% CI, 0.1 to 1.00, p = 0.05, and OR, 0.1, 95% CI, 0.01 to 0.96; p < 0.05, respectively). In patients with persistent AF, posterior LA isolation is associated with a lower risk of a redo procedure, roof-dependent macro-reentry, and post-ablation AT in general as compared to controls who only received roof ablation. Posterior LA isolation also obviates the need for pacing maneuvers, and may be a more definitive endpoint than linear ablation at the LA roof.

Abstract 14874: Electrical Isolation of the Posterior Left Atrium is Associated With a Lower Incidence of Atrial Tachycardia in Patients With Persistent Atrial Fibrillation

Introduction: Patients may develop atrial tachycardia (AT) after left atrial (LA) ablation of persistent atrial fibrillation (AF). Hypothesis: We hypothesized that patients with persistent AF undergoing electrical isolation of the posterior wall of the LA would be less likely to experience AT, and specifically, roof-dependent tachycardia as compared to historical controls who only received linear ablation at the LA roof. Methods: The population consisted of 101 consecutive patients (age= 64.3±8.7 years, 70 males (69%), LA=4.6±0.8 cm, ejection fraction=48.5±16%) undergoing their initial procedure for persistent AF. After pulmonary vein isolation, patients either underwent posterior LA isolation (n=50; study group) or linear ablation at the LA roof with verification of conduction block by established pacing maneuvers (n=51; control group) Results: During the initial procedure for AF, electrical isolation of the posterior LA or linear block at the LA roof were achieved in all patients in the study or control groups, respectively. During follow-up, patients in the study group were less likely to develop AT (9/50 [18%] vs. 18/51 [35%]; p=0.02), roof-dependent (1/50 [2%] vs. 8/51 [16%]; p=0.008), and multi-loop AT (6/50 [12%] vs. 14/51 [27%]; p=0.03) as compared to controls. A repeat procedure was performed in 18 (34%) and 28 (55%) patients in the study and control groups, respectively (p=0.03). After a mean follow-up of 25.3 ± 13, and 50.3 ± 27.3 months, 45 of the 50 study (90%), and 44 of the 51 control patients (86%) remained in sinus rhythm (p=0.72), with 12 and 13 patients taking antiarrhythmic medications, respectively (p=0.43) Conclusions: In patients with persistent AF, posterior LA isolation is associated with a lower risk of a redo procedure, roof-dependent macro-reentry, and post-ablation AT in general as compared to controls who only received linear ablation of the left atrial roof. Posterior LA isolation also obviates pacing maneuvers, the results of which might be equivocal, and may be a more definitive endpoint of linear ablation at the LA roof

Effects of additional ablation of low-voltage areas after Box isolation for persistent atrial fibrillation.

BackgroundPrevious studies reported that ablation of low‐voltage areas (LVAs) after pulmonary vein isolation (PVI) improves the success rate in persistent atrial fibrillation (PerAF) patients with LVAs. However, the need for LVA ablation in addition to the posterior left atrial isolation, Box isolation (BOXI), for PerAF is unclear. We evaluated the effects of LVA ablation after BOXI for PerAF with LVAs.MethodsIn 115 patients with PerAF (75 longstanding PerAF), LA voltage maps were created during sinus rhythm after PVI. Subsequently, BOXI was performed. In 61 patients without LVAs (<0.5 mV), BOXI alone was performed. Fifty‐four patients with LVAs were randomly assigned to BOXI plus LVA ablation (33 patients) or BOXI alone (21 patients).ResultsThe rate of AF termination or cardioversion after BOXI was significantly higher than that after PVI (100% vs 88%, P < 0.001). The inducibility of atrial tachyarrhythmia after BOXI was significantly lower than that after PVI (27% vs 100%, P < 0.001). During 24 ± 9 months of follow‐up after a single procedure, atrial tachyarrhythmia‐free rate in the patients with LVAs, was significantly lower than that without LVAs (65% vs 82%, P = 0.043). However, the success rate was not significantly different between the BOXI plus LVA ablation group and the BOXI alone group of patients with LVAs (67% vs 62%, P = 0.722).Conclusion BOXI facilitates AF termination and its non‐inducibility. Among patients with PerAF, BOXI alone may be adequate in cases without LVAs. Although cases with LVAs have higher risk of AF recurrence, additional LVA ablation does not improve the outcomes much.

Cryoballoon antral pulmonary vein isolation vs contact force-sensing radiofrequency catheter ablation for pulmonary vein and posterior left atrial isolation in patients with persistent atrial fibrillation

The role of cryoballoon ablation (CBA) for antral pulmonary vein isolation (APVI) has not been well established in persistent atrial fibrillation (PerAF). Isolation of the left atrial posterior wall (BOX) after APVI has been suggested to improve the efficacy of radiofrequency catheter ablation (RFA) in PerAF. The purpose of this study was to compare characteristics and clinical outcomes of APVI by CBA vs APVI + BOX by contact force-guided RFA (CF-RFA) in patients with PerAF. APVI was performed in 167 consecutive patients with PerAF (mean age 64 ± 9 years; left atrial diameter 46 ± 6 mm) using CBA (n = 90) or CF-RFA (n = 77). After APVI, a roofline was created in 33 of 90 patients (37%) in the CBA group and BOX was performed in all 77 patients in the CF-RFA group. During 21 ± 10 months of follow-up after a single ablation procedure, 37 of 90 patients (41%) in the CBA group (APVI) and 39 of 77 (51%) in the CF-RFA group (APVI + BOX) remained in sinus rhythm without antiarrhythmic drugs (AADs) (P = .22). During repeat ablation, APVI + BOX using CF-RFA was performed in 20 of 90 patients (22%) and in 18 of 77 patients (23%) who initially underwent CBA or CF-RFA, respectively. At 19 ± 10 months after repeat ablation, sinus rhythm was maintained in 55 of 90 patients (61%) and 52 of 77 patients (68%) in the CBA and CF-RFA groups without AADs, respectively (P = .39). In PerAF, an initial approach of APVI by CBA or APVI+ BOX by CF-RFA has a similar efficacy of 40%-50% without AADs. After repeat ablation for APVI + BOX by CF-RFA in ∼25%, sinus rhythm is maintained in 60%-70% of patients without AADs.

Posterior Left Atrial Isolation as a Strategy for Repeat Ablation in Recurrent Persistent Atrial Fibrillation: Following an Index Pulmonary Vein Isolation Procedure

Background: Posterior left atrial isolation (PLAI) is an evolving strategy for patients with persistent atrial fibrillation (AF). We sought to assess its utility in patients with recurrent persistent AF following pulmonary vein isolation.

Procedural and Clinical Outcomes of a Strategy of Posterior Left Atrial Isolation in Patients with Paroxysmal Atrial Fibrillation Undergoing Repeat Procedures: Where all or Nearly all Pulmonary Veins are Isolated

Procedural and Clinical Outcomes of a Strategy of Posterior Left Atrial Isolation in Patients with Paroxysmal Atrial Fibrillation Undergoing Repeat Procedures: Where all or Nearly all Pulmonary Veins are Isolated

Procedural and Clinical Outcomes of Posterior Left Atrial Isolation as Primary Procedure for Atrial Fibrillation Ablation in a Population of Patients Predicted to have Poorer Outcomes

Procedural and Clinical Outcomes of Posterior Left Atrial Isolation as Primary Procedure for Atrial Fibrillation Ablation in a Population of Patients Predicted to have Poorer Outcomes

Posterior left atrial isolation for atrial fibrillation in left ventricular diastolic impairment is associated with better arrhythmia free survival

BackgroundPatients with left ventricular diastolic impairment (LVDI) have higher rates of arrhythmia recurrence following atrial fibrillation (AF) ablation. Past studies have implicated the posterior left atrium (LA) in atrial arrhythmia maintenance in conditions that cause LVDI. We prospectively compared posterior LA isolation (PLAI) with wide antral isolation (WAI) in patients with LVDI having AF ablation. MethodsWe conducted a sub-study of a previously published large randomized control study that compared PLAI with WAI. Two hundred and twenty consecutive consenting patients referred for catheter ablation of AF (paroxysmal 135, persistent 48, long standing persistent 37) were recruited (female 43, mean age 59±10years). Transthoracic echocardiography identified 50 (23%) patients with LVDI and preserved left ventricular systolic function (ejection fraction≥50%). Cox regression analysis was utilized to identify independent predictors of atrial arrhythmia after ablation. ResultsPatients were followed for median 4.6 (inter quartile range 4.0–5.5) years. Patients with LVDI having PLAI had better arrhythmia free survival than patients randomized to conventional ablation (Log rank P=0.028). The only independent predictor of recurrence utilizing Cox regression analysis was ablation strategy (2.3 [1.15–4.74], P=0.026). ConclusionPosterior isolation of the LA results in superior atrial arrhythmia free survival in patients with LVDI. Further investigation is required to determine potential mechanisms. Clinical trial registrationhttp://www.anzctr.org.au;ACTRN12606000467538

Invited Commentary

Invited Commentary

Interim Results of the 5-Box Thoracoscopic Maze Procedure

In accordance with the Cox-Maze paradigm, successful treatment of atrial fibrillation (AF) requires (1) complete posterior left atrial isolation, (2) elimination of corridors for perimitral reentry, (3) elimination of cardiac venous (superior vena cava and coronary sinus) arrhythmogenic foci, (4) complete autonomic denervation, and (5) occlusion or removal of the left atrial appendage. Using a totally thoracoscopic approach, isolation of all left atrial arrhythmogenic substrate is achieved through the creation of 5 discrete but contiguous compartments, thereby enabling unambiguous verification with bidirectional block. Since no previous closed-chest procedure incorporates all these end points, an update on patient outcomes is reported. One hundred seventy-nine consecutive patients with antiarrhythmic drug-resistant AF (3 paroxysmal, 5 persistent, 171 longstanding persistent cases), known preoperatively for 5.7 (range 0.5 to 25) years, underwent the 5-box thoracoscopic Maze procedure. Only 1 patient suffered a serious procedural complication (sternotomy for pulmonary artery injury). Postoperative rhythm surveillance consisted of 1 week of continuous ambulatory monitoring at 3, 6, 13, and 24 months. Failure was defined as any tachyarrhythmia exceeding 30 seconds beyond the 3-month anniversary. Freedom from AF was observed in 137 of 142 patients at 3 months, 115 of 119 patients at 6 months, 75 of 78 patients at 13 months, and 24 of 25 patients at 24 months. Two patients remain in sinus rhythm on low-dose antiarrhythmia therapy. Warfarin is discontinued only after the first monitoring session confirms rhythm stability. Replication of the left atrial Cox-Maze lesion set through a totally thoracoscopic approach isolates virtually all arrhythmogenic substrate. Meticulous verification of compartment integrity allows for outcomes equivalent to the Cox-Maze benchmark.

Posterior Left Atrial Isolation Results in Fewer Arrhythmia Recurrences than Wide Antral Isolation: A Randomised Trial

Introduction: Single ring electrical isolation of the posterior left atrium and the pulmonary veins (SRI) improved AF free survival but not atrial tachyarrhythmia free survival compared to wide antral pulmonary vein isolation (WAI) after one procedure. Outcomes of these techniques after repeat procedures are unclear. Methods: We randomly assigned 220 highly symptomatic AF patients (58±10 years old; 180 male; 135 paroxysmal, 85 persistent/longstanding persistent) to undergo either SRI or WAI, with or without additional left lateral mitral isthmus line (MIL) ablation. Patients with recurrences >3 months later were offered a repeat procedure then followed clinically and with 7-day Holter studies. Results: Over 2.4±0.9 years follow up 99 patients underwent a repeat procedure (15 required a third procedure and 3 required a fourth). SRI resulted in better 2-year atrial tachyarrhythmia free survival than WAI after up to 2 procedures (82±4% vs. 69±5% p=0.04) and after up to 4 procedures (88±3% vs. 76±4% p=0.04). However, MIL ablation did not affect survival rates after up to 2 or 4 procedures. Conclusions: SRI results in fewer recurrences than WAI on long term follow up after up to 2 or 4 procedures.

Single Ring Posterior Left Atrial Isolation Results in Fewer Recurrent Atrial Arrhythmias than Wide Antral Isolation after two or More Procedures

Single Ring Posterior Left Atrial Isolation Results in Fewer Recurrent Atrial Arrhythmias than Wide Antral Isolation after two or More Procedures

P-wave Measurements and Electrical Reconnection of the Posterior Left Atrium after Catheter Ablation for Atrial Fibrillation

Recurrent atrial arrhythmias (RAAs) following posterior left atrial isolation (PLAI) for atrial fibrillation are common and are associated with reconnection of the PLA and pulmonary veins. We aimed to show that P-wave duration (PWD) and P-wave area under the curve (PWAUC) changes in patients undergoing PLAI can be measured using signal-averaged electrocardiogram (SAECG), and that reversal of these changes in patients with RAAs can be used to noninvasively detect reconnection. SAECG recordings before and after PLAI in 52 patients were analyzed for changes in PWD and PWAUC and also in 26 of these patients who had a repeat procedure for RAA. PWD and PWAUC reduced significantly in most leads following PLAI (mean 104 ± 11 ms to 93 ± 15 ms [P < 0.001] and 3.53 ± 1.23 microvolt seconds (μVs) to 2.87 ± 1.23 μVs [P = 0.001], respectively). Reconnection was observed in 20 of 26 patients at the repeat procedure. Compared to after the first procedure, reconnected patients had increased PWD and PWAUC (e.g., the increase in V4 was 14.1 ± 20.9 ms [P = 0.01] and 0.98 ± 1.17 μVs [P = 003], respectively) at the repeat procedure, while nonreconnected patients had decreased PWD and PWAUC (in V4, it was decreased by 11.5 ± 7.0 ms [P = 0.05] and 0.97 ± 0.33 μVs [P = 0.001]). A change in lead V4 PWAUC > -0.29 μVs for detecting reconnection had a sensitivity of 94% and specificity of 100% (receiver operator characteristic area under the curve 0.97, P = 0.005). PLAI reduces PWD and PWAUC while reconnection increases them both. SAECG may be able to detect reconnection of the PLA noninvasively.

Vagal denervation and reinnervation after ablation of ganglionated plexi

Surgical ablation of ganglionated plexi has been proposed to increase efficacy of surgery for atrial fibrillation. This experimental canine study examined electrophysiologic attenuation and recovery of atrial vagal effects after ganglionated plexi ablation alone or with standard surgical lesion sets for atrial fibrillation. Dogs were divided into 3 groups: group 1 (n = 6) had focal ablation of the 4 major epicardial ganglionated plexi fat pads, group 2 (n = 6) had pulmonary vein isolation with ablation, and group 3 (n = 6) had posterior left atrial isolation with ablation. All fat pads were ablated. Sinus and atrioventricular interval changes during bilateral vagosympathetic trunk stimulation were examined before and both immediately and 4 weeks after ablation. Vagally induced effective refractory period changes and mean QRST area changes (index of local innervation) were examined in 5 atrial regions. Sinus and atrioventricular interval changes and heart rate variability decreased immediately after ablation, but only sinus interval changes were restored significantly after 4 weeks in all groups. Ablation-modified vagal effects on effective refractory period or QRST area changed heterogeneously in groups 1 and 2. In group 3, regional vagal effects were attenuated extensively postablation in both atria. Posterior left atrial isolation with ablation incrementally denervated the atria. In the long term, vagal stimulation increased QRST area changes relative to control values in all groups. Heart rate variability was also assessed. Ganglionated plexi ablation significantly reduced atrial vagal innervation. Restoration of vagal effects at 4 weeks suggests early atrial reinnervation.