The recently-described left atrial appendage (LAA) neck is a truncated cone-shaped structure that connects the LAA orifice to its lobe. It shows malformations in some cases, but their exact description and clinical significance are unknown. Therefore, the aim of this study was to provide a detailed anatomical and morphometric analysis of LAA neck malformations in clinical context. A total of 250 autopsied human hearts (20.0% women, 46.7 ± 18.2 years old) were examined for mural malformations: spikes and bulges. Endocardial roughness of the LAA neck with a depth <2 mm and no recognizable epicardial protrusion was defined as ectopic trabeculation. LAA neck malformations were found in 13.6%, bulges in 10.0% of the hearts examined, spikes in only 3.2%, and ectopic trabeculations in 24.8%. In one case, both a bulge and a spike were found in the LAA neck. Most LAA neck roughness was observed on the aortic and venous surfaces of the LAA neck. Those surfaces were the most common locations for malformations and ectopic trabeculations. The LAA wall was significantly thinner than the surrounding neck wall within the bulges and the ectopic trabeculations, but not in the spikes.

The left atrial appendage (LAA) is well known as a source of cardiac thrombus formation. Despite its clinical importance, the LAA neck is still anatomically poorly defined. Therefore, this study aimed to define the LAA neck and determine its morphometric characteristics. We performed three-dimensional reconstructions of the heart chambers based on contrast-enhanced electrocardiography-gated computed tomography scans of 200 patients (47% females, 66.5 ± 13.6 years old). The LAA neck was defined as a truncated cone-shaped canal bounded proximally by the LAA orifice and distally by the lobe origin and was present in 98.0% of cases. The central axis of the LAA neck was 14.7 ± 2.3 mm. The mean area of the LAA neck walls was 856.6 ± 316.7 mm2 . The LAA neck can be divided into aortic, arterial (the smallest), venous (the largest), and free surfaces. All areas have a trapezoidal shape with a broader proximal base. There were no statistically significant differences in the morphometric characteristics of the LAA neck between LAA types. Statistically significant differences between the sexes in the main morphometric parameters of the LAA neck were found in the central axis length and the LAA neck wall area. The LAA neck can be evaluated from computed tomography scans and their three-dimensional reconstructions. The current study provides a complex morphometric analysis of the LAA neck. The precise definition and morphometric details of the LAA neck presented in this study may influence the effectiveness and safety of LAA exclusion procedures.

Abstract Introduction Previous research has revealed a relationship between left ventricular (LV) function and incidence of stroke in atrial fibrillation (AF) but the mechanism remains unknown. Purpose Given that the left atrial appendage (LAA) is located in the vicinity of the LV base we hypothesized that the LV longitudinal contraction has an impact on the LAA function, LAA thrombus (LAAT) formation, and occurrence of ischemic stroke (Figure 1A). The aim of this study was to investigate this phenomenon using transesophageal echocardiography (TEE). Material and methods We included in our study 105 consecutive patients (age 59±11; 55 men) undergoing TEE-guided cardioversion for AF. LV longitudinal function was assessed using the mitral annulus plane systolic excursion (MAPSE). LAA function was evaluated using the LAA emptying velocity (LAAEV) and LAA ejection fraction (LAAEF) (Figure 1B). The presence LAAT and spontaneous echo contrast (SEC) were evaluated as well. Results Our patients had a median CHADS2vasc score = 3 (IQR 2–4), LVEF=50±11%, and MAPSE=7.3±1.7mm. MAPSE showed a positive significant correlation with both LAAEV (r=0.34; p&amp;lt;0.01) and LAAEF (r=0.23; p&amp;lt;0.05) (Figure 2). LVEF correlated significantly with LAAEV (r=0.42, p&amp;lt;0.01), and LAA area (r=−0.34; p&amp;lt;0.05), respectively. Additionally, patients who exhibited SEC had significantly lower LAAEF as well as LAAEV when compared with patients without SEC: 31±12% vs 38±12% P=0.022 and 35±18cm/s vs 49±21cm/s P=0.005. Patients who displayed both SEC and LAAT had wider LAA neck when compared to the rest of the group (21.46±3.96mm vs. 18.23±3.78mm; P=0.021). Logistic regression analysis revealed that MAPSE independently predicted the occurrence of ischemic stroke both in univariate and multivariate models that also included the CHADSvasc2 score. Conclusions LV longitudinal contraction appears to influence LAA function. This relationship could potentially have an impact on occurrence of thromboembolic events in patients with atrial fibrillation. Funding Acknowledgement Type of funding sources: None.

The aim of this study was to evaluate the anatomic topography of the circumflex artery (Cx) and left atrial appendage (LAA) and to determine the safety zones for epicardial LAA closure and LAA occlusion procedures. The left coronary artery was segmented and visualized from 116 computed tomography angiography scans. Four points were located on the Cx portion periappendicularly, starting from the entry point. The landing zone plane was defined as parallel to the LAA orifice at the level of the beginning of the periappendicular course of the Cx, and the plane of the neck bend was located at the end of the LAA neck. A distance smaller than 2 mm was considered a dangerous distance. The distance between the Cx and the LAA landing zone was 4.3 ± 2 mm. The distance between the Cx and the LAA neck bend was 5.1 ± 2.2 mm. The distance between the Cx and the LAA bottom surface was 5.8 ± 2.9 mm. In 38.8% of patients, at least 1 distance between Cx and LAA was smaller than 2 mm in at least 1 dimension. These distances occurred in 30.2% of the LAA landing zone dimensions, 19.8% of LAA neck bend dimensions, and 11.2% of the LAA bottom surface distances. The study showed that most dangerous distances (30.2%) occurred in the LAA landing zone dimension. The data showed that landing zones more distal from the orifice of the LAA are safer in terms of Cx damage. Therefore, LAA closure should always be performed with caution, to avoid iatrogenic complications.

No studies have compared Watchman 2.5 (W2.5) with Watchman FLX (FLX) devices to date. We aimed at comparing the FLX with W2.5 devices with respect to clinical outcomes, left atrial appendage (LAA) sealing properties and device-related thrombus (DRT). All consecutive left atrial appendage closure (LAAC) procedures performed at two European centres between November 2017 and February 2021 were included. Procedure-related complications and net adverse cardiovascular events (NACE) at 6 months after LAAC were recorded. At 45-day computed tomography (CT) follow-up, intra- (IDL) and peri- (PDL) device leak, residual patent neck area (RPNA), and DRT were assessed by a Corelab. Out of 144 LAAC consecutive procedures, 71 and 73 interventions were performed using W2.5 and FLX devices, respectively. There were no differences in terms of procedure-related complications (4.2% vs. 2.7%, P = 0.626). At 45-day CT, the FLX was associated with lower frequency of IDL [21.3% vs. 40.0%; P = 0.032; odds ratio (OR): 0.375; 95% confidence interval (CI): 0.160-0.876; P = 0.024], similar rate of PDL (29.5% vs. 42.0%; P = 0.170), and smaller RPNA [6 (0-36) vs. 40 (6-115) mm2; P = 0.001; OR: 0.240; 95% CI: 0.100-0.577; P = 0.001] compared with the W2.5 group. At 45 days, rate of DRT as detected by CT and/or transoesophageal echocardiography (TOE), was higher with W2.5 (6.0% vs. 0%, P = 0.045). At 6-month follow-up, NACE did not differ between groups. In this cohort of consecutive LAACs, FLX as compared to W2.5, was associated with similar procedure-related complications and 6-month NACE, but with improved LAA neck coverage, and lower IDL and DRT.

Introduction: Atrial fibrillation (AF) is a significant risk factor for embolic stroke originating from the left atrial appendage (LAA). LAA occlusion is recommended in patients that are not amenable to anticoagulation therapy because of elevated CHADS 2 or CHA 2 DS 2 -VASC score. We assessed the risk of stroke off anticoagulants in AF patients following LAA occlusion with appendage clip device. Methods: One hundred eighty-five AF patients (age 66±13, males 69%, CHADS 2 2.6± 0.8, CHA 2 DS 2 -VASC 3.5± 1.2) that received surgical left atrial appendage occlusion device (clip) were included in this analysis. Transesophageal echocardiogram (TEE) was performed at the end of the procedure to evaluate successful closure of the antrum of the LAA and was repeated at 1 and 6-month post-procedure. Patients remained on oral anticoagulants for 1-month post-procedure after which it was discontinued. All patients were monitored for thrombo-embolic complications for at least 1 year by TEE, clinic visits at 3-month intervals and phone calls by our research staffs. Result: The follow-up TEE revealed the LAA clip to be stable without any secondary displacement. No LAA thrombus was detected. Interestingly, in 177 (95.6%) patients, TEE revealed the proximal part of the smooth antrum of the LAA neck below the clip, to be still open. At the end of the 24±3 months of follow-up, no stroke or transient ischemic attack (TIA) or other neurological events were observed in the study population (0 of 155, 0%). Conclusions: In patients with AF in whom oral anticoagulation is deemed unsuitable because of high CHADS 2 or CHA 2 DS 2 -VASC score, left atrial appendage closure with surgical clip device seems to be safe and effective in preventing stroke. It is relatively common to find incomplete obliteration of the LAA with the surgical clip with the proximal portion of the smooth antrum still remaining open as the clip is typically seen to be placed higher up in the LAA neck. However, presence of the open smooth-antrum did not increase the risk of stroke even after discontinuation of anticoagulants.

PERCUTANEOUS LEFT ATRIAL APPENDAGE OCCLUSION : INITIAL EXPERIENCE WITH THE ARTICULATED ULTRASEPT LAA OCCLUDERTM

Atrial fibrillation (AF) is associated with an increased risk for embolic stroke originating from the left atrial appendage (LAA). A recently introduced LAA epicardial clip occluder, the AtriClip PRO, can be applied through midsternotomy or small thoracotomy. We assessed the safety and efficacy of a new surgical approach to apply the AtriClip PRO and exclude the LAA through right minithoracotomy and transverse sinus. The AtriClip PRO was applied in 24 patients with the new approach. Intraoperative transesophageal echocardiography was used to exclude LAA thrombi at baseline and evaluate LAA perfusion and residual neck postoperatively. Mean (SD) age was 64.5 (8.6) years; 95% of the patients had nonparoxysmal AF with median AF duration of 39 months (interquartile range, 9.3-85.3 months), and mean (SD) left atrium diameter was 4.5 (0.7) cm (range, 3.1-5.7 cm). In one attempt, the clip was not deployed because of severe adhesions in the transverse sinus area. The procedural success rate was 95%. Nine minimally invasive mitral valve repairs were combined with surgical ablation; the rest were isolated right minithoracotomy Cox maze procedures. There was no remaining LAA neck in 71% of the patients. Perioperative outcomes were acceptable, and median length of stay was 5.5 days. The development of a reliable approach to LAA management during minimally invasive surgical ablation through right minithoracotomy has been challenging. This new approach is safe and effective and should offer a superior and consistent early and long-term solution compared with the current approach of endocardial stitch closure.

Atrial fibrillation (AF) is the most common sustained arrhythmia and is associated with substantial morbidity. The prevalence of AF in the United States is expected to rise to between 5.6 and 12 million in 2050.1 AF is associated with a 4- to 5-fold increased risk of ischemic stroke after adjustment for other risk factors,2 and paroxysmal, persistent, or permanent AF increases stroke risk to a similar degree. Oral anticoagulants (OACs) reduce the risk of thromboembolism, yet they are underused.3–6 Novel OACs are noninferior or superior to warfarin for the prevention of stroke and systemic embolism and are more convenient because they do not require ongoing monitoring.7–10 However, major challenges to long-term therapy with vitamin K antagonists and novel OACs include a substantial ongoing hazard of major bleeding, noncompliance, side effects, and, in the case of the novel OACs, lack of an available antidote. The left atrial appendage (LAA) is the predominant nidus for thrombus formation in AF, and transcatheter LAA closure has emerged as a potential alternative to oral anticoagulation in at-risk AF patients. AF is associated with mechanical dysfunction of atrial tissue. Loss of contractile function in the LAA can lead to local stasis and thrombus formation, which may then embolize into the systemic circulation. The observation that >90% of thrombi found in patients with nonvalvular AF and stroke are in the LAA supports this mechanistic sequence.11 In addition, low Doppler inflow velocities, spontaneous echocardiographic contrast, and the presence of thrombus in the LAA have been associated with high stroke rates in AF patients.12 These data lend support to the hypothesis that the elimination of the LAA may serve as a preventive strategy for AF-related stroke. Morphological features of the LAA may influence stroke risk. Larger LAA neck diameter …

Background The left atrial appendage (LAA) has been identified as a culprit for thromboembolic complications in the setting of atrial fibrillation (AF). LAA amputation has been integral to surgical treatment of AF since its early inception. As such, strategies to eliminate blood flow within the LAA have been developed and have proven their efficacy in preventing thromboembolic complications (1). These techniques are based on creating a mechanical barrier eliminating the LAA from blood flow, thereby preventing stasis that will cause thrombus formation. This mechanical barrier can be placed either endocardially (using either catheter-based techniques or sutures during open heart surgery) or epicardially. The main difference between these two approaches is that epicardial techniques involve the external application of mechanical force at the base of the LAA, hence truly closing the neck of LAA at its orifice, which over time leads to irreversible LAA fibrosis and subsequent disappearance (2). Only recently has the focus shifted towards the LAA, due to thromboembolic complications after oral anticoagulation in patients with elevated CHADS-VASC scores (1). But more importantly, the negative electrophysiological properties of the LAA might become a game changer as endocardial and epicardial LAA exclusion strategies produce different electrophysiological results.

POSTER PRESENTATIONS

Risk of Stroke/TIA in Patients With Atrial Fibrillation. Most strokes in patients with atrial fibrillation (AF) arise from thrombus formation in left atrial appendage (LAA). Our aim was to identify LAA features associated with a higher stroke risk in patients with AF using magnetic resonance imaging and angiography (MRI/MRA). The study included 144 patients with nonvalvular AF who were not receiving warfarin and who underwent MRI/MRA prior to catheter ablation for AF. LAA volume, LAA depth, short and long axes of LAA neck, and numbers of lobes were measured. Of the 144 patients, 18 had a prior stroke or transient ischemic attack (TIA) (13 and 5, respectively). Compared with patients who had no history of stroke/TIA, these patients were older, had higher prevalence of hypertension and hyperlipidemia and had higher LAA volume (22.9 ± 9.6 cm(3) vs. 14.5 ± 7.1 cm(3) , P < 0.001). Their LAA depth (3.76 ± 0.9 cm vs. 3.21 ± 0.8 cm, P = 0.006) and the long and short axes of the LAA neck (3.12 ± 0.7 cm vs. 2.08 ± 0.7 cm, P < 0.001; 2.06 ± 0.5 cm vs. 1.37 ± 0.4 cm, P < 0.001, respectively) were larger. Using stepwise logistic regression model, the only statistically significant multivariable predictors of events were age (OR = 1.21 per year, 95% CI 1.06-1.38, P = 0.004), aspirin use (OR = 0.039, 95% CI 0.005-0.28, P = 0.001), and LAA neck dimensions (short axis × long axis) (OR = 3.59 per cm(2) , 95% CI 1.93-6.69, P < 0.001). LAA dimensions predict strokes/TIAs in patients with AF. LAA assessment by MRI/MRA can potentially be used as an adjunctive tool for risk stratification for embolic events in AF patients.

Background: The left atrial appendage (LAA) has been identified as a frequent source of cardiac thrombus associated with systemic embolism in atrial fibrillation (AF). The aim of this study was to identify morphological characteristics of the LA and LAA that may confer higher stroke/TIA risk. Methods: We enrolled 119 patients with AF who underwent 3D-CT examination. We assessed LA and LAA anatomy and categorized LAA morphology and LAA position and counted the number of LAA lobes. Thirty one patients had a history of stroke/TIA (S group) and the others (88 patients) were free (NS group). There were no significant differences in age between two groups. Results: The LA size (41.9±6.1 mm) and LA volume (108.2±40.5 mm3) in S group were similar to those of NS group (42.3±6.6 mm and 98.0±35.8 mm3, p=0.7 and p=0.2, respectively). There were no significant differences in LAA volume (p=0.8) and LAA neck diameter (p=0.2) between two groups (22.3±4.2 mm3 and 10.1±3.4 mm in S group and 22.6±5.1 mm3 and 11.1±5.0 mm in NS group). There were no significant differences in LAA morphology, LAA position and the number of LAA lobes between two groups. Conclusions: Morphological and dimensional characteristics of the LA and LAA did not determine the risk of stroke/TIA in patients with AF.

The left atrial appendage (LAA) has been proven to be the most important site of thrombus formation in patients with atrial fibrillation (AF). However, the information regarding the morphometric alteration of the LAA related to the outcome of AF ablation is still lacking. Thus, we evaluated the long-term changes of the LAA morphology in patients undergoing catheter ablation of AF using magnetic resonance angiography (MRA). Group 1 included 15 controls without any AF history. Group 2 included 40 patients with drug-refractory paroxysmal AF. They were divided into two subgroups: group 2a included 30 patients without AF recurrence after pulmonary vein (PV) ablation. Group 2b included 10 patients with late recurrence of AF. The LAA morphology before and after (20 +/- 11 months) ablation was evaluated by three-dimensional MRA. The group 2 patients had a larger baseline LAA size (including the LAA orifice, neck, and length) and less eccentric LAA orifice and neck. After the AF ablation, there was a significant reduction in the LAA size in the group 2a patients, and the morphology of the LAA neck became more eccentric during the follow-up period. In group 2b, the LAA size increased and no significant change in the eccentricity of the orifice and neck could be noted. The morphometric remodeling of the LAA in the AF patients could be reversed after a successful ablation of the AF. Progressive dilation of the LAA was noted in the patients with AF recurrence. These structural changes in the LAA may play a role in reducing the potential risk of cerebrovascular accidents.

Analysis of the left atrial appendage by magnetic resonance angiography in patients with atrial fibrillation

Transesophageal Echocardiographic Assessment of Right Atrial Appendage Anatomy and Function: Comparison with the Left Atrial Appendage and Implications for Local Thrombus Formation