Left Atrial Appendage Isolation Research Articles

Durability of wide-area left atrial appendage isolation: Results from extensive catheter ablation for treatment of persistent atrial fibrillation

Extensive ablation strategies are currently performed in addition to pulmonary vein isolation (PVI) to improve the clinical outcome of patients with drug-refractory persistent atrial fibrillation (AF). Ablation of complex fractionated atrial electrograms (CFAEs), linear lesions, and/or isolation of the left atrial appendage (LAA) are thought to improve arrhythmia-free survival. The purpose of this study was to assess the durability of wide-area left atrial appendage isolation (LAAI) achieved by PVI, an anterior line, and a mitral isthmus line. Seventy-one patients with intentional or incidental LAAI during repeat catheter ablation for treatment of persistent AF were included. The initial ablation strategy was PVI. Additional ablation strategies were performed only if PVI failed to maintain stable sinus rhythm. Durability of LAAI was assessed during a subsequent ablation procedure for arrhythmia recurrences (n = 23) or a subsequent percutaneous LAA closure (n = 48). LAAI was performed after a mean of 3 ± 1 procedures. Ablation strategies included circumferential PVI in 71 patients (100%), mitral isthmus line in 64 (90%), anterior line in 60 (85%), CFAE in 27 (38%), and roof line in 13 (18%). LAAI occurred after ablation and bidirectional block of LA linear lesions in 63 patients (89%) and during extensive CFAE ablation in 8 patients (11%). After a median of 105 [61;426] days, the LAA remained electrically isolated in 52 of 71 patients (73%). Wide-area LAAI after extensive catheter ablation for persistent AF is durable in the majority of patients. The potential clinical benefit of LAAI for maintaining stable sinus rhythm requires further investigation.

Left Atrial Appendage Isolation in Patients With Longstanding Persistent AF Undergoing Catheter Ablation: BELIEF Trial

BackgroundLongstanding persistent (LSP) atrial fibrillation (AF) is the most challenging type of AF. In addition to pulmonary vein isolation, substrate modification and triggers ablation have been reported to improve freedom from AF in patients with LSPAF. ObjectivesThis study sought to assess whether the empirical electrical isolation of the left atrial appendage (LAA) could improve success at follow-up. MethodsThis was an open-label, randomized study assessing the effectiveness of empirical electrical left atrial appendage isolation for the treatment of LSPAF. Patients were randomly assigned to undergo empirical electrical left atrial appendage isolation along with extensive ablation (group 1; n = 85) or extensive ablation alone (group 2; n = 88). Recurrence of atrial arrhythmias was the primary endpoint. Secondary endpoints included cardiac-related hospitalization, all-cause mortality, and stroke at follow-up. ResultsMajor clinical characteristics were not different between the 2 groups. At 12-month follow-up, 48 (56%) patients in group 1 and 25 (28%) in group 2 were recurrence free after a single procedure (unadjusted hazard ratio [HR] for recurrence with standard ablation: 1.92; 95% confidence interval [CI]: 1.3 to 2.9; log-rank p = 0.001). After adjusting for age, sex, and left atrial size, standard ablation was predictive of recurrence (HR: 2.22; 95% CI: 1.29 to 3.81; p = 0.004). During repeat procedures, empirical electrical left atrial appendage isolation was performed in all patients. After an average of 1.3 procedures, cumulative success at 24-month follow-up was reported in 65 (76%) in group 1 and in 49 (56%) in group 2 (unadjusted HR: 2.24; 95% CI: 1.3 to 3.8; log-rank p = 0.003). ConclusionsThis randomized study showed that both after a single procedure and after redo procedures in patients with LSPAF, empirical electrical isolation of the LAA improved long-term freedom from atrial arrhythmias without increasing complications. (Effect of Empirical Left Atrial Appendage Isolation on Long-term Procedure Outcome in Patients With Persistent or Longstanding Persistent Atrial Fibrillation Undergoing Catheter Ablation [BELIEF]; NCT01362738)

Update on Atrial Fibrillation

Atrial fibrillation (AF), the most prevalent cardiac arrhythmia, is categorized into 4 different groups on the basis of the duration of the arrhythmia episodes. If AF terminates spontaneously or with intervention within 7 days from onset, it is paroxysmal AF; AF of more than 7 days in duration is persistent AF; continuous AF of more than one year's duration is longstanding persistent AF; and permanent AF is the condition that ensues when the patient and his or her physician mutually decide not to pursue the restoration or maintenance of sinus rhythm by any means.1

Left Atrial Appendage: Embryology, Anatomy, Physiology, Arrhythmia and Therapeutic Intervention.

Known for the pathological connection to atrial fibrillation (AF), the left atrial appendage (LAA) is the most common source of thromboembolism in patients with AF and may be an arrhythmogenic source for the maintenance of AF. Potential interventions of the LAA for stroke prevention have recently been developed through better understanding its anatomy and physiology. Occlusion of the LAA is an alternative to the use of life-long anticoagulation in selected nonvalvular AF cases. The PROTECT-AF (The WATCHMAN LAA Closure Device for Embolic PROTECTion in Patients with Atrial Fibrillation) and PREVAIL (Randomized Trial of LAA Closure vs. Warfarin for Stroke/Thromboembolic Prevention in Patients with Non-valvular Atrial Fibrillation) randomized controlled trials demonstrated that LAA exclusion using the Watchman percutaneous device is not inferior to warfarin. However, the appendage is structurally complex and has considerable morphological variations among individuals, and it can be challenging to generalize the device for all patients. Continued technological developments including occlusion/ligation through epicardial, endocardial, or surgical approaches, as well as operator expertise regarding LAA anatomy, physiology, and pathophysiology, should improve interventional outcomes. Furthermore, the optimal strategy for re-entrant tachyarrhythmias arising from LAA remains unknown. Whereas an observational study suggested that LAA isolation was more effective than focal ablation, LAA isolation may be associated with significant impairments in LAA contractility, predisposing individuals to a risk of thrombosis.

P-Wave Morphology and Electrical Activity of the Isolated Left Atrial Appendage on 12-lead ECG in Patients with Recurrent Atrial Tachyarrhythmias After Pulmonary Vein Isolation

Left atrial appendage isolation(LAAI) may occur during catheter ablation of complex atrial tachyarrhythmias(aTa). We compare P-waves before and after LAAI and characterize LAA activity on the 12-lead ECG after LAAI. Twenty-five patients were analyzed after LAAI. P-wave amplitude, duration, and morphology before and after LAAI were analyzed. Automaticity in the isolated LAA was identified, and magnified 12-lead surface ECGs were analyzed for LAA activity, amplitude, duration, and morphology. The isolated LAA area was measured using a 3D mapping system. P-wave amplitude and duration during sinus rhythm was 0.09 mV and 103.57 ms before LAAI and 0.09 mV and 102.25 ms after LAAI, respectively. Precordial leads, I, II, III, and aVF were positive. Lead aVR was negative. Lead aVL was −/+. There were no significant differences in P-wave morphology before and after LAAI. Twenty-one of 25 (84%) patients had LAA automaticity after LAAI. Twelve of 21 (57%) patients had automaticity associated with visible LAA activity on the surface ECG. The average LAA activity amplitude and duration was 0.02 mV and 67.7 ms, respectively. Precordial leads, I, II, III, and aVF were positive. Lead aVR was negative/isoelectric. Lead aVL was positive/isoelectric. The mean isolated LAA area was 29.1 cm2. The mean percentage area of isolated LAA vs total LA area was 22.6%. LAA activity can be visible on 12-lead ECG in 57% of patients after LAAI. They have smaller amplitudes and shorter durations compared to P-waves.

229-06: Left Atrial Appendage Electrical Isolation for Long-Standing Persistent Atrial Fibrillation: Computational Three-Dimensional Left Atrial Appendage Wall Thickness Maps and Histological Analysis to Guide Ablation

Purpose of the study: Left atrial appendage (LAA) electrical isolation may improve the efficacy of persistent atrial fibrillation (AF) ablation. We have previously demonstrated substantial acute LAA reconnection rates in both canines and humans following electrical isolation. We sought to establish whether LAA ostial thickness variations could be evaluated by a novel computational algorithm applied to a pre-procedure CT. Methods used: LAA wall thickness was calculated by solving the Laplace equation between the boundary conditions assigned to the endo- and epi-cardial surfaces from CT scans of 20 patients. Comparison was made with acute LAA reconnection sites in 20 patients with longstanding persistent AF undergoing LAA isolation following conventional AF ablation and with ostial LAA thicknesses from a group of cadaveric human hearts without previous ablation matched with the ablation group. Summary of the results: The anterior (2.5 ± 0.8 mm) and superior (2.4 ± 1.2 mm) LAA margins were thickest histologically. This correlated with recorded sites of acute reconnection. The algorithm calculated thicker tissue at the same ostial sites. The thickest region was at the anterior wall; the inferior wall was the thinnest (2.4 ± 1.5 mm vs 1.8 ± 0.8 mm, p = 0.039).

Effect of left atrial appendage excision on procedure outcome in patients with persistent atrial fibrillation undergoing surgical ablation

Catheter ablation is less successful for treatment of persistent atrial fibrillation (PersAF) than for paroxysmal atrial fibrillation. Some studies suggest that left atrial appendage (LAA) isolation in addition to pulmonary vein isolation (PVI) is required to maximize the benefits for PersAF after ablation. The purpose of this study was to compare the efficacy and safety of 2 surgical ablation approaches for PersAF via video-assisted thoracoscopy: PVI + box lesion and PVI + box lesion + LAA excision. We randomly assigned 176 patients with PersAF to video-assisted thoracoscopic surgical ablation with PVI + box lesion (88 patients) or PVI + box lesion + LAA excision (88 patients). The primary endpoint was freedom from any documented atrial arrhythmia lasting >30 seconds after a single ablation procedure without antiarrhythmic drug (AAD). After 18 months of follow-up, 61 of 86 patients (70.9%) assigned to PVI + box lesion were free from recurrent atrial fibrillation compared to 64 of 87 patients (73.6%) assigned to PVI + box lesion + LAA excision after a single ablation procedure without AAD (P = .73). Freedom from any atrial arrhythmia after a single procedure with or without AAD was also nonsignificant (70.9% vs 74.7%, respectively). There were no significant differences between groups with regard to adverse events, including death, transient ischemic attack, stroke, pneumothorax, and hydrothorax. Among patients with PersAF, no reduction in the rate of recurrent atrial fibrillation was found when LAA excision was performed in addition to PVI and box lesion during surgical ablation.

Unexpectedly High Incidence of Stroke and Left Atrial Appendage Thrombus Formation After Electrical Isolation of the Left Atrial Appendage for the Treatment of Atrial Tachyarrhythmias.

Electric left atrial appendage (LAA) isolation (LAAI) may occur during catheter ablation of atrial tachyarrhythmias. Data regarding the risk of thromboembolic events and stroke after LAAI are sparse. This study evaluated the incidence of LAA thrombus formation and thromboembolic events after LAAI. Fifty patients had LAAI (age=71 years; female=56%; CHA2DS2-VASc score before ablation =3 [2;3]). LAAI patients were compared with matched patients with comparable baseline characteristics who underwent atrial fibrillation ablation without LAAI (n=50). Ablation strategies in the LAAI group included pulmonary vein isolation in 50 (100%), left atrial isthmus line in 47 (94%), anterior line in 45 (90%), complex atrial fractionated potentials in 24 (48%), and roofline in 14 (28%) patients. Transesophageal echocardiography was performed during follow-up in 47/50 (94%) patients in the LAAI group and in all patients of the control group. Oral anticoagulation (OAC) independent of CHA2DS2-VASc score was strongly recommended in all patients. During a median follow-up of 6.5 (4-12) months, stroke occurred in 2 patients on OAC and transient ischemic attack in one without OAC in the LAAI group. In the remaining 47 patients, LAA thrombus was identified on transesophageal echocardiography in 10 (21%) patients (OAC=9; no OAC=1). In the control group, no LAA thrombus was detected and no stroke occurred (P<0.001). Stable sinus rhythm was maintained in 32 patients (64%) of the LAAI group after a median follow-up of 6.5 months (4-12), including 17/32 patients on antiarrhythmic drugs. After LAAI, an unexpectedly high incidence of LAA thrombus formation and stroke was observed despite OAC therapy.

The clinical efficacy of left atrial appendage isolation caused by extensive left atrial anterior wall ablation in patients with atrial fibrillation.

The left atrial appendage (LAA) can be a source of atrial fibrillation (AF) triggering or a part of reentry. We sought to determine the characteristics and clinical outcomes of patients with LAA potential delay including electrical isolation (LAAEI) following LA anterior wall (LAAW) ablation for AF. LAAW ablation cases were collected from among 846 patients who underwent catheter ablation (CA). A total of 89 patients were enrolled; they were divided into three groups according to the extent of LAA potential injury. The ejection fractions (EFs) of the LAA and LA were measured by means of LA angiograms. The mean age of all patients was 56.2 ± 10.7years (74 males, 83%). In 47 of the 89 patients, an LAA potential delay was identified after LAAW ablation (group 2). LAAEI was seen in 18 patients (group 3). In the remaining 24 patients, there was no LAA potential delay or LAAEI (group 1). The mean EF decreased significantly after CA in group 3 (P < 0.001). At 21-month follow-up, three patients (17%) in group 3 had recurrence compared with 11 (42%) in group 2 and 12 (46%) in group 3 (P = 0.028). In multivariate analysis, diabetes mellitus and LAA potential delay were independent predictors of AF recurrence (P = 0.021, P = 0.008, respectively). Ablation of the LA anterior wall near the insertion of Bachmann's bundle and the neck of the LAA resulting in LAA potential delay or electrical isolation is effective in preventing recurrence of atrial fibrillation.

Abstract 14764: Left Atrial Appendage Function and Risk of Stroke After Left Atrial Appendage Electrical Isolation in Patients With Long-Standing Persistent AF: Results From the BELIEF Randomized Trial

Introduction: The Belief Randomized trial sought to assess whether the empirical isolation of the left atrial appendage (LAA) in addition to an extensive ablation could improve success at follow up in patients with long standing persistent (LSP) atrial fibrillation (AF). The aim of this sub-analysis of the trial aimed to evaluate the LAA contraction at the 6 month repeat Trans-esophageal echocardiogram (TEE). Methods: Patients with LSP AF undergoing ablation were enrolled and randomly assigned to undergo empirical LAA isolation along with an extensive ablation or extensive ablation alone. All patients undergoing LAA isolation received a TEE at the 6 months follow up, irrespective of their underlying rhythm. We evaluated TEE parameters and compared thromboembolic complication between groups. Results: We enrolled 173 pts with average age of 63.8 ± 8.5 years and 85.5% male pts. LAA isolation was performed in 101 pts. LAA was not isolated in 72 pts. Follow-up TEE was performed in all pts with LAA isolation. The peak flow velocity in the appendage was low (&lt;0.4 m/s) in 56.4% (57/101) patients. The doppler across the mitral valve demonstrated E-wave to A-wave ratio (E/A) of 2.64 ± 1.4. All patients had E/A &gt;1, out of which 55.4 %( 56/101) had E/A &gt; 2 (p=0.16). One (1.2%) LAA thrombus [Oral anticoagulant warfarin INR subtherapeutic] and 1 (1.2%) LAA smoke [Oral anticoagulant warfarin, INR : 2.24] were detected in the LAA isolation group as an incidental finding at TEE before redo ablation procedure. One patient (0.99%) had stroke in the LAA isolation group after warfarin discontinuation due to a surgical procedure, while 3 (4.2%) stoke/TIA occurred (p=0.31) in the no LAA isolation group (2 pts on warfarin, 1 pt on aspirin). Conclusion: The results of this study show that LAA isolation does not increase the risk of tia/stroke at follow up. This risk appears to be related to the compliance to oral anticoagulation.

How Could Pre-Procedural Imaging Guide Successful Left Atrial Appendage Closure?

REFER TO THE PAGE 211-218 Atrial fibrillation (AF) is the most common sustained arrhythmia and strongly associated with ischemic stroke.1) In patients with AF, the main site of thrombus formation is the left atrial appendage (LAA).2) Autopsy and surgical data have suggested that about 90% of atrial thrombi in AF patients originate from the LAA.3) There are two reasonable ways to prevent ischemic stroke events in patients with AF. The first is maintenance of anticoagulation. The second is to isolate the LAA as a major embolic source from the systemic circulation. Multiple randomized, controlled trials have suggested that oral anticoagulation (OAC) decrease the risk of stroke in patients with AF.4) However, long-term OAC is contraindicated in 14% to 44% of AF patients with risk of stroke.5) Because there are various barriers against maintenance of long-term OAC such as the risk of bleeding, inconvenience of dose adjustments, drug interactions, and restrictions on diet.6) Other novel anticoagulants are also limited by the side effects, and the risk of bleeding from systemic administration of these agents.7) Because the LAA is a separate anatomic structure, it may be relatively easily isolated from systemic circulation by excision or ligation. Recently, less invasive technique using percutaneous transcatheter have been introduced for LAA isolation by occlusion of this anatomical structure with implantable devices.8) The PROTECT AF (Watchman Left Atrial Appendage System for Embolic Protection in Patients with Atrial Fibrillation) trial was planned to determine whether systemic anticoagulation with warfarin, the most commonly used anticoagulant, could be replaced by LAA closure with a percutaneously positioned device. This final results of the PROTECT AF trial followed up for an accumulated exposure of 1588 patient-years revealed LAA closure with the Watchman device to be non-inferior to systemic anticoagulation with warfarin regarding prevention of stroke, systemic embolism, and cardiovascular death.9) On the basis of these data, LAA closure has been decided a class IIb recommendation in the 2014 ACC/ASA guideline as an alternative strategy to prevent stroke. For this procedure to be accepted as an alternative, there must be a high success rate. Although success rate of the LAA closure is generally high, peri-device leakage of LAA persists due to incomplete closure.9),10) During percutaneous LAA closure for stroke prophylaxis, the geometric variability of the LAA ostium may result in an incomplete seal of the LAA. To understand the technical limitations of LAA closure, it is important to consider the anatomical variations of the LA and LAA geometry. The geometry of LA and LAA, a detailed knowledge of its anatomical characteristics and relationship might be very useful when planning the procedure. As LA and LAA geometry is complex, there are limited available data about the predictors of successful procedure. The anatomical relationship of LAA and interatrial septum (IAS) may affects the success rate of device implantation.11) In this issue, Chung et al.12) introduced 3-dimensional anatomical relation of IAS and LAA orifice as a predictor of peri-device leakage after LAA closure. One of the novel and interesting aspects of this study is that they use new novel analysis program for accurate measurement of 3-dimensional relationship between IAS and LAA orifice and found that 3-dimensional angulation between IAS and LAA significantly associated with development of peri-device leakage after LAA occlusion. In this study, the angle between the IAS plane and the line linking the LAA orifice midline and foramen ovale was measured using 3-dimensional geometric cardiac CT analysis. Measurement of this new parameter can provide more detail geometric information and predict success of the procedure. In addition, it might be helpful to select catheter and to decide the direction of IAS puncture site. This study is the first study that anatomical relationship of IAS and LAA orifice might affect peri-device leakage. However, clinical implication of peri-device leakage after LAA occlusion is unclear. Despite some previous studies suggested that the incomplete LAA occlusion was not associated with cardioembolic stroke event,10) understanding the clinical impact of peri-device leakage would be critical. As the authors commented in the limitation, larger sample size, prospective and long-term follow up data are needed to determine the clinical implication of peri-device leak after LAA occlusion. Despite some limitations, this study results suggested that novel anatomical parameter could be measured by their new software and this parameter is useful to predict peri-device leakage after LAA device closure.

Concomitant unipolar radiofrequency ablation of nonparoxysmal atrial fibrillation in rheumatic and degenerative valve disease.

The aim of this study was to compare the results of concomitant unipolar radiofrequency ablation of nonparoxysmal atrial fibrillation (AF) between rheumatic and degenerative valve disease (RHD versus DVD). Between 2005 and 2012, 96 patients underwent AF ablation with unipolar radiofrequency concurrently with heart valve surgery. They were followed in three months and at a median follow-up of 39 (18 to 61) months. The mean age was 62 years old. Most patients had RHD (54.2%) and dilated left atria (LA, diameter 52.6 ± 5.8 mm). Patients with RHD were more likely to be younger and have larger LA. 88 patients (92%) underwent prophylactic closure of the left atrial appendage (LAA). Pulmonary vein-isolation, box lesion, LAA isolation, and left isthmus line were performed by radiofrequency, along with other right atrial cut-and-sew lines. Overall, surgical complications occurred in 25% of the patients and pacemaker implantation (17.7%) was the most frequently observed. In-hospital mortality rate was zero. The median length of stay was 8 (7, 12) days. Seventy-one percent of the patients were in sinus rhythm at discharge. Sinus rhythm maintenance was 45% and 40% in three months and at a median follow-up of 39 (18 to 61) months (269 patient-years), respectively. There was no statistically significant difference between RHD and DVD. In the multivariate analysis, LA ≥50 mm was the single independent predictor of AF recurrence at three months. Radiofrequency ablation of AF concurrently with heart valve surgery is poorly effective in patients with multiple adverse risk factors. Patients with RHD and DVD had similar rates of sinus rhythm recovery. LA ≥50 mm was the single predictor of AF recurrence at three months.

Left atrial appendage electrical isolation and concomitant device occlusion: A safety and feasibility study with histologic characterization.

Left atrial appendage (LAA) electrical isolation is reported to improve atrial fibrillation ablation outcomes. However, loss of mechanical function may increase thromboembolic risk. The aim of this study was to evaluate the feasibility and safety of LAA occlusion after electrical isolation in a canine model. Nine canines underwent LAA isolation with irrigated radiofrequency ablation after pulmonary vein (PV) isolation. Entrance and exit block were confirmed with intravenous adenosine after 30 minutes. The LAA was then occluded with a Watchman device. Device position was assessed at 10 days by using transthoracic echocardiography. At 45 days, LAA isolation was assessed epicardially. Hearts were then examined macroscopically and histologically. All 36 PVs and 8 of 9 LAAs (89%) were electrically isolated. Acute LAA reconnection occurred in 4 of 8 LAAs (50%). All were reisolated. The mean ablation time was 51 ± 19 minutes, including 24 ± 18 minutes for LAA isolation. LAA occlusion was successful in all cases. One animal died of a primary intracranial bleed due to anticoagulant hypersensitivity 36 hours after the procedure. Transthoracic echocardiography at 10 days confirmed satisfactory device positions and no pericardial effusion. At 45 days, 7 of 8 (88%) had persistent LAA electrical isolation. All devices were stable without evidence of erosion. Microscopy revealed complete device-tissue apposition and a mature connective tissue layer overlying the device surface in all cases. LAA electrical isolation and mechanical occlusion can be performed concomitantly in this animal model, with no displacement or mechanical erosion of the appendage at 45 days. This technique can potentially improve success rates and obviate the need for chronic anticoagulation. Future studies should address efficacy, safety, and feasibility in humans.

Atrial structure and function 5 years after successful ablation for persistent atrial fibrillation: an MRI study.

The atrial outcome after extensive ablation is unknown. We sought to quantify atrial structure and function years after successful ablation for persistent atrial fibrillation (PsAF). We studied after 80 ± 15 months 26 patients (54 ± 8 years, 1 woman) with PsAF successfully treated by ablation (2.2 ± 0.7 stepwise approach procedures, cumulative RF duration 126 ± 37 minutes). At follow-up atrial scar burden and atrial outflows were quantified using delayed-enhanced and velocity-encoded MRI, respectively. Cine imaging was used to quantify atrial conduit function (CF), active emptying fraction (AEF), expansion index (EI), and the inter-appendage mechanical activation delay. Patients underwent exercise testing at baseline and follow-up. LA and RA scar extent were 29 ± 6 and 4.3 ± 2.8%, respectively. LA and RA AEF were 10.0 ± 5.3 and 30 ± 8%. Mean inter-appendage delay was 83 ± 47 ms [42-217]. Complete LAA isolation was found in 3 patients. A wave was absent in 9/26 patients. LA scar extent related to the number of procedures (R = 0.58, P = 0.002) and total RF duration (R = 0.56, P = 0.003). Among follow-up characteristics, LA scar extent related to LAAEF (R = -0.73, P < 0.0001), LAEI (R = -0.64, P = 0.0003), A-wave peak (R = -0.72, P < 0.0001), and inter-appendage mechanical delay (R = 0.47, P = 0.02). At multivariable analysis, LA scar extent was independently related to LAAEF and LAEI. LAAEF and LA scar extent correlated with exercise capacity at follow-up (R = 0.44, P = 0.02, and R = -0.40; P = 0.04). LA contractility and compliance are markedly impaired years after successful PsAF ablation. LA dysfunction is closely related to scar burden.

LEFT ATRIAL APPENDAGE LIGATION AND ABLATION FOR PERSISTENT ATRIAL FIBRILLATION (LAALA-AF REGISTRY)

Left atrial appendage (LAA) isolation is known to be an important adjunctive therapy to improve outcomes of pulmonary vein isolation in patients with persistent AF. Percutaneous endo-epicardial LAA closure system (LARIAT) can result in both mechanical and electrical exclusion of the LAA and may

The effects of LAA ligation on LAA electrical activity

The arrhythmic role of the left atrial appendage (LAA) has been implicated in the maintenance of persistent atrial fibrillation. LAA isolation with catheter ablation has been successful but is limited by the risk of tamponade and electromechanical dissociation with the potential for LAA thrombus formation. To assess whether LAA ligation results in LAA electrical isolation. A total of 68 patients with contraindication or intolerance to oral anticoagulation therapy underwent LAA ligation with the LARIAT suture delivery device. Patients had unipolar [n = 30(44%)] or bipolar [n = 38(56%)] voltage measurements pre- and post-LAA ligation. All 68 patients underwent successful LAA ligation. There was a statistically significant reduction in the mean LAA voltage from pre-ligation (unipolar pre-ligation voltage 1.1 ± 0.53 mV; bipolar pre-ligation voltage 4.7 ± 2.83 mV) to post-ligation (unipolar post-ligation voltage 0.3 ± 0.38 mV; bipolar post-ligation voltage 0.6 ± 0.27 mV). Ninety-four percent of the patients had a reduction in the LAA voltage after the closure of the snare, with 10 of 30 (33%) of the patients having complete elimination of LAA voltage with the initial tightening of the suture. Pacing from the LAA after the closure of the snare resulted in lack of capture of the left atrium in 28 of 31 patients. The snare closure of the LAA using the LARIAT device produces an acute reduction in the LAA voltage and inhibits the capture of the left atrium during LAA pacing. Future studies are needed to determine whether LAA ligation affects atrial fibrillation burden.

Safety and efficacy of the modified anterior line for treatment of perimitral flutter: a single centre experience

Background: The modified anterior line (MAL) is routinely used in our centre since 2004 with increasing experience with this line. We sought to investigate the acute and long-term efficacy of the MAL for ablation of perimitral flutter (PMFL). Methods: We included 80 consecutive patients (mean age 66+8 years, 74% male, mean LA diameter: 47+6mm) who underwent a catheter ablation of PMFL using a MAL in our centre between 2008 and 2012. The MAL was deployed between the anterolateral mitral annulus and the ostium of the left superior pulmonary vein (PV) using an irrigated tip catheter (power limit 30-40W, temperature 43°C, perfusion rate 30-40 mL/min). PMFL was diagnosed using entrainment manoeuvres and activation mapping. It was either the presenting arrhythmia after ablation of persistent atrial fibrillation (AF) (n=60, 75%), an intermediate atrial tachycardia (AT) occurring during atrial fibrillation (AF) ablation (n=18, 22.5%) or a primary PMFL (n=2, 2.5%). In 22/80 (27.5%) patients, PMFL was due to a gap in a previously deployed MAL during linear ablation for persistent AF. Acute success was defined as termination of PMFL or its change to another stable form during MAL deployment with confirmation of bidirectional line bloc using differential pacing. Results: Acute success was achieved in 67/80 (84%) patients. In 12 patients (15%) an additional mitral isthmus line between left inferior PV and lateral mitral annulus was necessary, with ablation deep inside the coronary sinus in 8/12 (67%) patients. In 4 patients (5%) both lines failed to achieve termination of PMFL. Complications included 1 tamponade during MAL deployment and 2 cases of isolation of the left atrial appendage (LAA) in patients with otherwise extensive LA ablation. During follow-up, bloc of the MAL could be checked in 28 patients who underwent a repeat ablation procedure. Bidirectional bloc of the MAL was confirmed in 16/28 (57%) of patients while only 9/28 (32%) of patients had a recurrence of PMFL. 19/28 (68%) had another type of AT. Conclusions: The MAL is highly effective for the acute treatment of PMFL. Isolation of LAA is a possible complication in patients with extensive LA ablation. The challenge remains, as in other types of lines, the long term maintenance of complete block.

Abstract TP417: Minimally-Invasive Video-Assisted Ligation of Left Atrial Appendage in Atrial Fibrillation: Stroke Prevention Strategy

Background: Non-valvular atrial fibrillation (AF) is a leading cause of embolic stroke, especially in the elderly population. The vast majority of thrombo-emboli in AF patients originate within the left atrial appendage (LAA). Effective and complete isolation of the LAA has been demonstrated to have a similar stroke-reduction effect as chronic anticoagulation. This study presents our initial experience with a novel minimally-invasive video-assisted (MIVA) thoracoscopic approach to epicardially isolate the LAA using the AtriClip device. Methods: Six consecutive AF patients (mean age 73.6 years, 3 of 6 male) with contra-indication to systemic anticoagulation underwent epicardial ligation of LAA using the AtriClip device. Procedure involved two 5mm ports and one 15mm port with application of the device at the base of the LAA under direct visualization. Immediate intra-operative confirmation of LAA isolation via trans-esophageal echocardiography (TEE) was obtained. Anticoagulation was not restarted post-operatively. Results: Average procedure length was 43mins and average length of stay was 72hours. All six patients had a non-complicated post-operative course. No stroke, myocardial infarction, renal failure or re-operation was encountered. No transfusions were needed. All patients were extubated in the operating room at conclusion of procedure and were ambulatory on the first postoperative day. 3 of 6 patients experienced excessive pleural drainage lasting 2-4 days postoperatively. TEE confirmation of complete LAA obliteration was achieved in all patients. Conclusions: MIVA LAA ligation appears to be a safe, effective and simple procedure to isolate the LAA in AF patients with contra-indication to anticoagulation. A multi-institutional trial to assess the efficacy of MIVA LAA ligation as a stroke prevention strategy is warranted and forthcoming.

Reply to the Editor—Masked Left Atrial Appendage Isolation During Ablation Of Persistent Atrial Fibrillation

We thank Drs. Di Biase and Natale for their interest in our case report1 and their fruitful discussion. According to their recent publication, the left atrial appendage (LAA), like the pulmonary veins, may harbor arrhythmogenic foci in approximately 30% of patients with long-standing persistent atrial fibrillation (AF), and LAA isolation demonstrates a beneficial effect in this population.2 These data are similar to that of our experience in patients with long-standing persistent AF.

Left Atrial Appendage: Extending the Search for New Sources of Atrial Fibrillation Triggers.

should be performed first after the PV isolation. Di Biase et al. performed LAA isolation in only patients in whom firing was documented in the LAA usually with administration of isoproterenol. In that study, LAA firing was documented in 27% of the patients with recurrences, which accounts for only 6.7% of all the patients that underwent AF ablation in their centers. More than a decade ago, we administered isoproterenol to induce triggers for PV focal ablation. Thus, we know isoproterenol is not always effective for the induction of arrhythmias. Even among the patients who did not exhibit any LAA firing, a cer tain number of those patients may benefit from LAA isolation. Another issue with the LAA isolation is the risk of future thromboembolisms. Almost half of the patients exhibited excellent LAA contraction at 6-months of follow-up. This may be due to passive blood flow or electrical reconnection. In the patients with depressed LAA contraction, however, the continuation of anticoagulation therapy or LAA occlusion needs to be considered. In patients with excellent LAA contraction at the midterm follow-up, it is unknown whether or not the LAA contraction will remain that way for the next 10 years. There remain issues to be solved concerning the LAA isolation; however, we recognized that the LAA is an important source of triggers in AF in addition to the thoracic veins.