The left atrial appendage: anatomy, function, and noninvasive evaluation

MRI-based modelling of left atrial flow and coagulation to predict risk of thrombogenesis in atrial fibrillation

Atrial fibrillation (AF), impacting nearly 50 million individuals globally, is a major contributor to ischaemic strokes, predominantly originating from the left atrial appendage (LAA). Current clinical scores like CHA₂DS₂-VASc, while useful, provide limited insight into the pro-thrombotic mechanisms of Virchow's triad-blood stasis, endothelial damage, and hypercoagulability. This study leverages biophysical computational modelling to deepen our understanding of thrombogenesis in AF patients. Utilising high temporal resolution Cine magnetic resonance imaging (MRI), a 3D patient-specific modelling pipeline for simulating patient-specific flow in the left atrium was developed. This computational fluid dynamics (CFD) approach was coupled with reaction-diffusion-convection equations for key clotting proteins, leading to an innovative risk stratification score that combines clinical and modelling data. This approach categorises thrombogenic risk into low (A), moderate (B), and high (C) levels. Applied to a cohort of nine patients, pre- and post-catheter ablation therapy, this approach generates novel risk scores of thrombus formation, which are based of mechanistic characterisation of all aspects of the Virchow's triad. Currently, thrombogenesis mechanisms are not factored in widespread clinical risks scores based on demographic characteristics and co-morbidities. Notably, some patients with a CHA₂DS₂-VASc score of 0 (lowest clinical risk) exhibited much higher risks once the individual pathophysiology was accounted for. This discrepancy highlights the limitations of the CHA₂DS₂-VASc score in providing detailed mechanistic insights into patient-specific thrombogenic risk. This work introduces a comprehensive method for assessing thrombus formation risks in AF patients, emphasising the value of integrating biophysical modelling with clinical scores to enhance personalised stroke prevention strategies.

The role of multi-modality imaging for the assessment of left atrium and left atrial appendage: a clinical consensus statement of the European Association of Cardiovascular Imaging (EACVI), European Heart Rhythm Association (EHRA) of the European Society of Cardiology (ESC)

Structural, architectural, contractile, or electrophysiological alterations may occur in the left atrium (LA). The concept of LA cardiopathy is supported by accumulating scientific evidence demonstrating that LA remodelling has become a cornerstone diagnostic and prognostic marker. The structure and the function of the LA and left atrial appendage (LAA), which is an integral part of the LA, are key elements for a better understanding of multiple clinical conditions, most notably atrial fibrillation, cardioembolism, heart failure, and mitral valve diseases. Rational use of various imaging modalities is key to obtain the relevant clinical information. Accordingly, this clinical consensus document from the European Association of Cardiovascular Imaging, in collaboration with the European Heart Rhythm Association, provides comprehensive, up-to-date, and evidence-based guidance to cardiologists and cardiac imagers for the best practice of imaging LA and LAA for the diagnosis, management, and prognostication of the patients.

Current evidence and indications for left atrial appendage closure

Atrial fibrillation (AF) is the most common arrhythmia worldwide and its prevalence increases with age. The main and most severe complication of AF is ischemic stroke, yet an estimated 50 % of eligible patients cannot tolerate or are contraindicated to receive oral anticoagulation (OAC). In patients with AF, the left atrial appendage (LAA) is the main source of thrombus formation. Percutaneous LAA closure (LAAC) has emerged over the past two decades as a valuable alternative to OAC for reducing the risk of strokes and systemic embolisms in patients with AF who cannot tolerate long-term OAC. With newer generation devices such as the Watchman (Boston Scientific, Natick, MA, USA) and Amulet (Abbott, Abbott Park, IL, USA) gaining approval from the US Food and Drug Administration in recent years, the safety and efficacy of LAAC in specific populations intolerant to OAC have increased and more patients are being treated. This systematic review provides the indications for LAAC and the evidence for evaluating the use of the currently available device therapies. We also examine the current unsolved problems with patient selection and postprocedural antithrombotic regimens.

Enhanced Endothelialization Using Resveratrol-Loaded Polylactic Acid-Coated Left Atrial Appendage Occluders in a Canine Model

Left atrial appendage occlusion (LAAO) is a well-established alternative to anticoagulation therapy for patients with atrial fibrillation who have a high bleeding risk. After occluder implantation, anticoagulation therapy is still required for at least 45 days until complete LAAO is achieved by neoendocardial coverage of the device. We applied a polylactic acid-resveratrol coating to the LAAO membrane to enhance endothelialization with the goal of shortening the anticoagulation therapy duration. Eighteen dogs were randomly divided into the experimental group (coated occluders) or the control group (noncoated occluders). The dogs were sacrificed in cohorts at days 14, 28, and 90 for anatomical and pathological examination to evaluate endothelialization and thrombus formation. Transesophageal echocardiography (TEE) was performed before sacrifice to evaluate device-related adverse events. According to the anatomical and pathological examinations, all except one LAAO cover exhibited larger or thicker tissue or neoendocardial coverage in the experimental group compared with the control group at the same sacrifice time points. All connection hubs were densely covered by endothelial cells at 90 days and completely covered at 28 days in the experimental group, while all connection hubs were thinly covered at 90 days and two connection hubs were exposed at 28 days in the control group. Pathological examination revealed no thrombus formation in the experimental group, while a small amount of thrombus was observed in one dog at 90 days and in two dogs at 28 days in the control group. Finally, TEE showed no peri-device leakage (PDL) in the experimental group, whereas a small amount of PDL was detected in one dog (3.2 mm) at 28 days and in one dog (3.7 mm) at 14 days in the control group. The resveratrol-loaded polylactic acid-covered LAAO device enhanced endothelialization and reduced thrombus formation and PDL. This effect could possibly reduce the anticoagulation therapy duration.

The potential role of cardiac CT in ischemic stroke: bridging cardiovascular and cerebrovascular health

Ischemic stroke, accounting for approximately 80% of all stroke cases, remains a leading cause of death and disability worldwide. Effective management of ischemic stroke is heavily influenced by its etiology, which can range from large-artery atherosclerosis and cardiac embolism to cerebral small-vessel occlusions and cryptogenic strokes. Cardioembolic stroke, which makes up about 30% of ischemic strokes, often leads to more severe symptoms and worse outcomes, necessitating anticoagulation therapy for prevention. Cryptogenic strokes, comprising over 25% of ischemic strokes, pose significant challenges for treatment and prevention due to their elusive nature. Thorough investigation of cardioembolic sources during the acute phase of stroke is crucial. While transthoracic and transesophageal echocardiography are traditional methods for detecting intracardiac thrombi and patent foramen ovale (PFO), cardiac CT has emerged as a non-invasive, efficient alternative. Cardiac CT can effectively visualize intracardiac thrombi, PFO, valvular abnormalities, tumors, and complex aortic plaques. This review discusses the potential applications of cardiac CT in ischemic stroke, emphasizing its role in identifying stroke etiology, predicting stroke risk, and assessing patient prognosis. The integration of advanced imaging technologies and artificial intelligence further enhances its diagnostic accuracy and clinical utility, promising to improve outcomes and reduce the healthcare burden associated with ischemic stroke.

First-in-Human Percutaneous Epicardial-Only Left Atrial Appendage Closure Using Sierra Left Atrial Appendage Ligation System

Background: In patients with atrial fibrillation and contraindications for oral anticoagulation, in which an increased risk of stroke remains, a left atrial appendage exclusion should be considered for elimination, because the left atrial appendage is the most common site of thrombus. The aim of this study is to present the first-in-human study results of the Sierra Aegis Left Atrial Appendage Ligation System, a new epicardial-only left atrial appendage closure system. Methods: This study was a prospective, first-in-human, single-center study evaluating the effectiveness and safety of the Sierra Aegis Left Atrial Appendage Ligation System device for epicardial left atrial appendage closure. Seven patients (mean age: 57.3 ± 10.6 years, 71.4% male) were qualified for a left atrial appendage closure because of an increased risk of bleeding with the need for lifelong anticoagulation pharmacology due to an increased risk of stroke. The patients' preoperative and intraoperative characteristics were collected. Patients were observed during their 1-month, 3-month, 6-month, and 1-year follow-up. Results: The mean procedure time was 21.2 ± 8.2 min. All patients spent 3 days in the hospital including monitoring, the performance of preoperative CT scans, and anatomical evaluation. No tamponade, bleeding, thrombus, or left atrial appendage leakage were observed during the procedure or in-hospital stay. During the 1-month, 3-month, 6-month, and 1-year follow-up visits, none of the patients reported any complications. No tamponade, leakage, or left atrial appendage thrombus were observed. Conclusions: This first-in-human study regarding Sierra use for left atrial appendage closure shows promising results regarding the effectiveness and safety of the Sierra device for use in humans.

Left atrial appendage aneurysm: a descriptive systematic review of 177 cases

INTRODUCTION

The left atrial appendage (LAA) is a distinct structure with unique developmental and structural characteristics. The LAA is involved in the formation of intra-atrial thrombi, particularly in patients with conditions such as atrial fibrillation and mitral valve disease. Left atrial appendage aneurysms (LAAA) are rare abnormal dilations of the LAA that may cause hazardous complications. However, there are limited data on the demographic features, clinical characteristics, management modalities, and prognosis of LAAA patients. This study aimed to conduct a systematic review of the reported cases of LAAA to explore the baseline characteristics, presentation, preferred diagnostic modalities, and optimal management of LAAA.

METHODS

A systematic review was conducted following the PRISMA guidelines. We performed a literature search using MEDLINE/PubMed and Google Scholar. Eligible articles published between January 1940 and November 2022 were included. The eligibility criteria included case reports and case series of LAAA in English language articles. The data extracted included information on the authors, publication year, patient characteristics, signs/symptoms, diagnostic procedures, treatments, and outcomes.

RESULTS

We identified 177 patients with LAAA in our study. There was a slight female predominance (50.9%), and the mean age was 29.7 years. Palpitations were the most common symptom reported, followed by shortness of breath and thromboembolic events. Transthoracic and transesophageal echocardiograms were the most common modalities for investigating and diagnosing LAAA, and the mean size of the aneurysm was 7.8 (5.7-9.6) × 5.9 (5.0-6.2) cm. Surgical resection is the treatment of choice for most patients with excellent prognoses. Older age and the presence of arrhythmia were significantly associated with thrombus formation and embolic events.

CONCLUSION

Left atrial appendage aneurysm is a rare but potentially life-threatening heart pathology that can lead to arrhythmias and thromboembolic events. Surgical resection appears to be the primary treatment option in the current literature, and most patients show improvement or are asymptomatic after treatment. Additionally, alternative approaches, such as transcatheter closure of LAAA, ablation, and medical treatments, have been reported as viable alternatives to surgical intervention.

Morphology and Function Assessment of Left Atrial Appendage in Patients With Atrial Fibrillation

Atrial fibrillation (AF) is among the most prevalent forms of clinically significant arrhythmia, and stroke incidence is among the most serious AF-related complications, causing high rates of morbidity and mortality among affected patients. The European Society of Cardiology guidelines recommend a thromboembolic event risk assessment based on the CHA2DS2-VASC score. However, stroke also occurs in some patients with a low CHA2DS2-VASC score. Therefore, it is necessary to improve thromboembolic risk stratification in AF patients. The left atrial appendage (LAA) is considered to be the most frequent site of thrombus formation. Approximately 47% of thrombi in valvular AF and 91% of thrombi in nonvalvular AF are localized in the LAA. Therefore, identification or exclusion of LAA thrombi is critical in many clinical situations. It is essential to assess LAA morphology and function using imaging modalities (particularly echocardiography) before, during, and after interventional procedures such as AF ablation and LAA occlusion. This review article describes the anatomical, physiological, and LAA assessment in daily practice.

Understanding the role of the left atrial appendage on the flow in the atrium

BACKGROUND

The exclusion/occlusion of the left atrial appendage (LAA) is a treatment option for atrial fibrillation (AF) patients who are at high risk of stroke and high risk of bleeding. As the role of the LAA is not well understood or explored, this study aims to assess its role on flow dynamics in the left atrium.

METHODS

Computational fluid dynamics (CFD) simulations were carried out for nine AF patients before and after LAA exclusion. The flow parameters investigated included the LA velocities, Time Averaged Wall Shear Stress (TAWSS), Oscillatory Shear Index (OSI), Relative Residence Time (RRT), and Pressure in the LA.

RESULTS

This study shows that, on average, a decrease in TAWSS (1.82 ± 1.85 Pa to 1.27 ± 0.96 Pa, p < 0.05) and a slight increase in OSI (0.16 ± 0.10 to 0.17 ± 0.10, p < 0.05), RRT (1.87 ± 1.84 Pa-1 to 2.11 ± 1.78 Pa-1, p < 0.05), and pressure (-19.2 ± 6.8 mmHg to -15.3 ± 8.3 mmHg, p < 0.05) were observed in the LA after the exclusion of the LAA, with a decrease in low-magnitude velocities.

CONCLUSION

The exclusion of the LAA seems to be associated with changes in LA flow dynamics. Further studies are needed to elucidate the clinical implications of these changes.

The Relationship Between Cardiac CT-based Left Atrial Structure and Epicardial Adipose Tissue and Postablation Atrial Fibrillation Recurrence Within 2 Years

PURPOSE

The aim of this study was to explore the association of cardiac CT-based left atrium (LA) structural and functional parameters and left atrial epicardial adipose tissue (LA-EAT) parameters with postablation atrial fibrillation (AF) recurrence within 2 years.

MATERIALS AND METHODS

Contrast-enhanced cardiac CT images of 286 consecutive AF patients (median age: 65 y; 97 females) who underwent initial ablation between June 2018 and June 2020 were retrospectively analyzed. Structural and functional parameters of LA, including maximum and minimum volume and ejection fraction of LA and left atrial appendage (LAA), and LA-EAT volume, were measured. The body surface area indexed maximum and minimum volume of LA (LAVI max , LAVI min ) and LAA (LAAVI max , LAAVI min ), and LA-EAT volume index (LA-EATVI) were calculated. Independent predictors of AF recurrence were determined using Cox regression analysis. The clinical predictors were added to the imaging predictors to build a combined model (clinical+imaging). The predictive performance of the clinical, imaging, and combined models was assessed using the area under the receiver operating characteristics curve (AUC).

RESULTS

A total of 108 (37.8%) patients recurred AF within 2 years after ablation at a median follow-up of 24 months (IQR=11, 32). LA and LAA size and LA-EAT volume were significantly increased in patients with AF recurrence ( P <0.05). After the multivariable regression analysis, LA-EATVI, LAAVI max , female sex, AF duration, and stroke history were independent predictors for AF recurrence. The combined model exhibited superior predictive performance compare to the clinical model (AUC=0.712 vs. 0.641, P =0.023) and the imaging model (AUC=0.712 vs. 0.663, P =0.018).

CONCLUSION

Cardiac CT-based LA-EATVI and LAAVI max are independent predictors for postablation AF recurrence within 2 years and may provide a complementary value for AF recurrence risk assessment.

Peri-device leakage and delayed endothelialization of the Watchman device: a computed tomography study

OBJECTIVES

This study aimed to explore the endothelialization process and assess the potential association between endothelialization and peri-device leak (PDL) following Watchman implantation via a quantitative method.

METHODS

This is a single-center retrospective study of consecutive patients undergoing LAAO between December 2015 and November 2021. Device endothelialization, compared between PDL and non-PDL group, were quantitatively analyzed based on hypoattenuated thickening in cardiac computed tomography angiography (CCTA). Advancement in endothelialization over time were explored using the Cochran-Armitage test and generalized estimating equation approach. Potential risk factors of delayed endothelialization were analyzed using the Cox proportional-hazards model.

RESULTS

A total of 172 patients (mean age, 68 years ± 10 [standard deviation], 114 men) were finally included. The average endothelialization ratio of the study population was 89.8 ± 7.2 percent. In the follow-up period of postprocedural 3 months to more than 12 months, an incremental trend of endothelialization over time was observed with the ratio of 85.8 ± 8.0, 89.6 ± 7.6, 92.2 ± 4.5, 94.3 ± 2.9 percent, respectively (p < 0.0001). Notably, patients without PDL exhibited a swifter advancement in endothelialization compared to those with PDL, irrespective of device size. The multivariable Cox regression model showed that PDL (HR = 2.113, 95%CI: 1.300-3.435, p = 0.003), DSP (HR = 1.717, 95%CI: 1.113-2.647, p = 0.014) were independent risk factors of delayed endothelialization.

CONCLUSION

CCTA holds promise as an effective means of quantitatively assessing device endothelialization. Endothelialization advanced gradually over time, with PDL potentially impeding device endothelialization.

CLINICAL RELEVANCE STATEMENT

A comprehensive understanding of the correlation between endothelialization ratio, time, and residual shunt can establish a more dependable foundation for determining the appropriate anticoagulation treatment following left atrial appendage closure.

KEY POINTS

Current recommendations for postleft atrial appendage occlusion anti-platelet and anticoagulation therapy are based on animal studies. Cardiac computed tomography angiography (CCTA) combined with the UNet neural network model enables the quantitative assessment of device endothelialization. This technique will allow for additional studies to better understand device endothelialization to optimize treatments in this population.

Left atrial appendage anatomy: clinical implications for cardiac procedures

The Left Atrial Appendage (LAA) is the most common source of thrombi during atrial fibrillation (AF) leading to stroke. With the increasing prevalence of AF and the growing number of patients requiring LAA involved interventions like exclusion and ablation, understanding LAA's anatomical intricacies becomes paramount importance. This study aims to provide anatomical data regarding LAA in relation to these procedures. Total 50 formalin-fixed cadaveric hearts were examined and various morphological and morphometric parameters were noted. The Cauliflower shape LAA (36%) was most common followed by Chicken Wing (34%), Cactus (18%), and Windsock (12%) shapes. The LAA orifice had greater horizontal diameter compared to the vertical diameter and was oval in shape in 64% cases. Diverticular structures called divots/ pits were present surrounding the LAA orifice in 36% cases with high variation in number, size, and distance from orifice. They were most commonly present towards the septal side and posterior wall side around the LAA orifice. The circumflex artery was the closest structure to LAA orifice with less than 5 mm distance in 76% cases. Other structures present close to the LAA were the Left Superior Pulmonary Vein and Mitral Valve. According to shape, the Non-Chicken Wing morphology of the LAA was associated with close running left circumflex artery, high OI (Ovality Index) of the orifice, and greater presence of divots. The LAA anatomy is complex with high amount of variability making it difficult to perform successful procedures. Given data can help clinicians in better planning and execution of cardiac interventions involving the LAA.

Device-Assisted Left Atrial Appendage Exclusion: From Basic Sciences to Clinical Applications

Device-assisted left atrial appendage exclusion plays a crucial role in the prevention of fatal ischemic complications in patients with atrial fibrillation and contraindications to anticoagulation treatment. Various devices with different safety profiles and device-related complications are available in daily practice to perform this procedure. In this review, the anatomy, physiology, and functions of the left atrial appendage were detailed, and all available devices used for epicardial and endocardial exclusion of the left atrial appendage and their clinical outcomes were discussed. Future research should aim to further investigate the long-term effects of left atrial appendage exclusion on body homeostasis, blood coagulation, and cardiac function.

Left atrial appendage orifice morphology in sickness and in health

BACKGROUND

The left atrial appendage (LAA) is the primary site of embolism in individuals with atrial fibrillation (AF). We aimed to evaluate the morphological features of the LAA orifice in patients with sinus rhythm, paroxysmal AF, and persistent AF using three-dimensional (3D) transesophageal echocardiography (TOE). We also intended to identify morphometric parameters of the LAA orifice that may be potentially associated with an increased risk of ischemic stroke.

METHODS

We prospectively enrolled 106 patients undergoing TOE. Patients were divided into three groups: group 1 (sinus rhythm), group 2 (persistent AF), and group 3 (paroxysmal AF). All patients underwent a comprehensive evaluation through transthoracic echocardiography (TTE) and TOE. Off-line analyses were performed of the recorded images.

RESULTS

The LAA minor orifice area and minimal orifice diameter were greater in patients with persistent AF compared with individuals in sinus rhythm. Patients with persistent AF also had deeper LAAs compared with those in sinus rhythm. None of the LAA orifice morphometric measures were related to ischemic stroke risk. The only independent predictors of ischemic stroke were heart rhythm and the CHA2DS2VASc score.

CONCLUSION

Persistent AF is associated with LAA dilation, increased depth, and larger orifice size. To our knowledge, this is the first study to demonstrate LAA orifice structural remodeling in patients with AF using 3D TOE.

Correlation between left atrial appendage morphology based on fractal dimension quantification and its hemodynamic parameters in patients with atrial fibrillation

AIMS

To investigate the relationship between left atrial appendage (LAA) morphology, quantified based on fractal dimension (FD), and LAA hemodynamic parameters in patients with atrial fibrillation (AF), in an effort to reveal the effect of LAA shape on blood flow.

MATERIALS AND METHODS

225 patients with AF who underwent cardiac computed tomography angiography (CTA) and transesophageal echocardiography (TEE) were enrolled. LAA morphology was quantified based on FD on cardiac CTA images, and LAA hemodynamic parameters, including injection fraction (EF), filling peak flow velocity (FV), maximum speed of emptying (PEV), and wall motion velocity (WMV), were assessed using TEE.

RESULTS

We divided the patients with AF into two groups based on a mean LAA FD of 1.32: the low FD group (n=124) and the high FD group (n=101). Compared to the low FD group, there were more patients with LAA circulatory stasis/thrombus (P=0.008) in the high FD group, as well as lower LAA FV (P=0.004), LAA PEV (P=0.007), and LAA WMV (P=0.007). LAA FD was an independent and significant determinant of LAA EF (β = -11.755, P=0.001), LAA FV (β = -17.364, P=0.004), LAA PEV (β = -18.743, P<0.001), and LAA WMV (β = -7.740, P=0.001) in multiple linear regression analysis.

CONCLUSIONS

LAA FD is an essential determinant of LAA hemodynamic parameters, suggesting that the relatively complex morphology of the LAA may influence its hemodynamics, which can correlate with embolic events.

Left atrial appendage thrombus is associated with a higher fractal dimension in patients with atrial fibrillation

PURPOSE

To assess the anatomical complexity of the left atrial appendage (LAA) using fractal dimension (FD) based on cardiac computed tomography angiography (CTA) and the association between LAA FD and LAA thrombosis.

MATERIALS AND METHODS

Patients with atrial fibrillation (AF) who underwent both cardiac CTA and transesophageal echocardiography (TEE) between December 2018 and December 2022 were retrospectively analyzed. Patients were categorized into normal (n = 925), circulatory stasis (n = 82), and thrombus groups (n = 76) based on TEE results and propensity score matching (PSM) was performed for subsequent analysis. FD was calculated to quantify the morphological heterogeneity of LAA. Independent risk factors for thrombus were screened using logistic regression. The diagnostic performance of FD and CHA2DS2-VaSc score for predicting thrombus was evaluated using the area under the receiver operating characteristics curve (AUC).

RESULTS

LAA FD was higher in the thrombus group (1.61 [1.49, 1.70], P < 0.001) than in the circulatory stasis (1.33 [1.18, 1.47]) and normal groups (1.30 [1.18, 1.42]) both before and after PSM. LAA FD was also an independent risk factor in the thrombus (OR [odds ratio] = 570,861.15 compared to normal, 41,122.87 compared to circulatory stasis; all P < 0.001) and circulatory stasis group (OR = 98.87, P = 0.001) after PSM. The diagnostic performance of LAA FD was significantly better than the CHA2DS2-VaSc score in identifying thrombus.

CONCLUSIONS

Patients with high LAA FD are more likely to develop LAA thrombus, and the use of FD provides an effective method for assessing the risk of thrombosis in AF patients, thereby guiding individualized clinical treatment.

Simulating left atrial arrhythmias with an interactive N-body model

BACKGROUND

Heart disease and strokes are leading global killers. While atrial arrhythmias are not deadly by themselves, they can disrupt blood flow in the heart, causing blood clots. These clots can travel to the brain, causing strokes, or to the coronary arteries, causing heart attacks. Additionally, prolonged periods of elevated heart rates can lead to structural and functional changes in the heart, ultimately leading to heart failure if untreated. The left atrium, with its more complex topology, is the primary site for complex arrhythmias. Much remains unknown about the causes of these arrhythmias, and computer modeling is employed to study them.

METHODS

We use N-body modeling techniques and parallel computing to build an interactive model of the left atrium. Through user input, individual muscle attributes can be adjusted, and ectopic events can be placed to induce arrhythmias in the model. Users can test ablation scenarios to determine the most effective way to eliminate these arrhythmias.

RESULTS

We set up muscle conditions that either spontaneously generate common arrhythmias or, with a properly timed and located ectopic event, induce an arrhythmia. These arrhythmias were successfully eliminated with simulated ablation.

CONCLUSIONS

We believe the model could be useful to doctors, researchers, and medical students studying left atrial arrhythmias.

Left atrial appendage thrombus with severe mitral stenosis: Responders and non-responders to anticoagulation

INTRODUCTION AND OBJECTIVE

Mitral stenosis (MS) is one of the most frequently observed valvular heart lesions in developing countries and is due to different etiologies. The effects of anticoagulation in different types of left atrial appendage (LAA) are unknown. The current study aimed to determine the resolution of LAA thrombus on transesophageal echocardiography (TEE) after three months of optimal anticoagulation in patients with different types of LAA at baseline cardiac computed tomography of patients with severe MS.

METHODS

This prospective cohort study observed the frequency of LAA thrombus resolution after three months of anticoagulation therapy in patients with severe MS. The response rate in different morphologies of LAA and locations was also assessed. Thrombus resolution after three months of warfarin therapy was assessed on repeat TEE.

RESULTS

A total of 88 patients were included, mean age 37.95±11.87 years. Repeat TEE showed thrombus resolution in only 27.3% of patients. The rate of thrombus resolution was 8/12 (66.7%), 4/28 (14.3%), 8/36 (22.2%), and 4/12 (33.3%) for patients with cactus, cauliflower, chicken wing, and windsock LAA type, respectively. The resolution rate was 0/12 (0%), 4/44 (9.1%), and 20/32 (62.5%) for patients with thrombus in the base, body, and tip of the LAA, respectively.

CONCLUSION

The cactus type of LAA morphology and thrombus at the LAA tip responded well to three months of anticoagulation, however, patients with thrombus in the LAA base and body and cauliflower and chicken wing morphology were non-responders and could benefit from early referral for surgical management.

Left Atrial Appendage Closure: A Single-Center Experience in a Population With a High Prevalence of End-Stage Renal Disease

Background Left atrial appendage closure (LAAC) has emerged as an alternative approach for mitigating thrombotic risk in nonvalvular atrial fibrillation patients. However, existing registries often lack representation of the Hispanic population, motivating this study to elucidate the demographic, clinical, and procedural characteristics, specifically among Hispanic patients undergoing this procedure. Methods Adult patients who underwent percutaneous LAAC between June 2017 and July 2022 at a high-complexity hospital in Bogotá, COL, were included. Baseline and procedural characteristics are reported. For patients with available follow-up data, major bleeding, thromboembolic events, and cardiovascular mortality were assessed. A subgroup analysis was conducted for patients with end-stage renal disease on dialysis. Results We included 33 patients. Follow-up data were available for 27 patients, with a mean follow-up period of 12.4 months. The median age of the cohort was 70 years (SD 9), with 58% being women. The median CHADS2 and HAS-BLED scores were 3 points (IQR 2 to 4) and 4 points (IQR 3 to 4), respectively. The 90-day cardiovascular mortality rate was 3.7%, whereas cardioembolic episodes and major bleeding events were reported at rates of 10.8 and 14.4 per 100 patient years, respectively. The long-term outcomes of patients on dialysis were comparable to those of nondialysis patients. Conclusions Our study reinforces existing evidence supporting the safety of LAAC, particularly in a multimorbid patient population with elevated bleeding and thrombotic risks. In this high-risk cohort, LAAC emerges as a feasible alternative for reducing thromboembolic risk. Notably, patients on dialysis demonstrated comparable long-term outcomes, suggesting the procedure's viability in this subgroup as well.

Left Atrial Appendage Closure Compared With Oral Anticoagulants for Patients With Atrial Fibrillation: A Systematic Review and Network Meta-Analysis

BACKGROUND

Percutaneous left atrial appendage closure (LAAC) has been suggested as an alternative to long-term oral anticoagulation for nonvalvular atrial fibrillation, but comparative data remain scarce. We aimed to assess ischemic and bleeding outcomes of LAAC compared with vitamin K antagonists (VKAs) or direct oral anticoagulants (DOACs) for the prevention of cardioembolic events in patients with atrial fibrillation.

METHODS AND RESULTS

Embase and MEDLINE were searched for randomized trials comparing LAAC, VKAs, and DOACs. The primary efficacy end point was any stroke or systemic embolism. Treatment effects were calculated from a network meta-analysis and ranked according to the surface under the cumulative ranking curve. Seven trials and 73 199 patients were included. The risk of the primary end point was not statistically different between LAAC versus VKAs (odds ratio [OR], 0.92 [95% CI, 0.62-1.50]) and LAAC versus DOACs (OR, 1.11 [95% CI, 0.71-1.73]). LAAC and DOACs resulted in similar risk of major or minor (OR, 0.93 [95% CI, 0.61-1.42]) and major bleeding (OR, 0.92 [95% CI, 0.58-1.46]); however, after exclusion of procedural bleeding, bleeding risk was significantly lower in those undergoing LAAC. Both LAAC and DOACs reduced the risk of all-cause death  compared with VKAs (LAAC versus VKAs: OR, 0.70 [95% CI, 0.53-0.91]; DOACs versus VKAs: OR, 0.90 [95% CI, 0.85-0.95], respectively). DOACs ranked as the best treatment for stroke or systemic embolism prevention (66.9%) and LAAC for reducing major bleeding (63.9%) and death (96.4%).

CONCLUSIONS

As a nonpharmacological alternative to oral anticoagulation for atrial fibrillation, LAAC showed similar efficacy and safety compared with VKAs or DOACs. Prospective confirmation from larger studies is warranted.

Crosslink between atrial fibrillation and cancer: a therapeutic conundrum

Atrial fibrillation (AF) is more common in patients with malignancies than in general population. The pathophysiological processes include the pro-inflammatory condition and the exaggerated inflammatory reaction to chemotherapy, radiotherapy, and surgery interventions. Thus, it is pivotal to decrease morbidity and mortality in this group by providing appropriate care and prevention. In this subset, the risk of thromboembolic and bleeding events is high and the common risk score such as CHA2DS2-VASc and HAS-BLED employed in non-oncologic patients have limited evidence in cancer patients. A paucity of evidence in the setting in individuals having both malignancies and atrial fibrillation entangle the clinician when it comes to therapeutic management. Tailored management is recommended of anticoagulation treatment could be difficult, and there is. In this review, we try to explain the mechanism of AF in cancer patients as well as its management in this setting.

Thoracoscopic Left Atrial Appendage Occlusion with the AtriClip PRO2: An Experience of 144 Patients

AIM

To report the clinical outcomes of thoracoscopic left atrial appendage occlusion (LAAO) with the AtriClip PRO2 device (Atricure Inc, Mason, OH, USA). Stroke risk reduction with LAAO in patients with atrial fibrillation is now well-established. Many surgical and percutaneous techniques have been used, with varying rates of success. The percutaneous devices have had issues with procedural complications and peridevice flow. Thoracoscopic AtriClip offers an epicardial linear closure of the appendage at its ostium. This study sought to evaluate its safety and efficacy in achieving complete LAA closure.

METHOD

This is a prospective series of thoracoscopic AtriClip PRO2 as a standalone procedure or a thoracoscopic AtriClip deployed as an adjunct to minimal access cardiac and thoracic surgery. Study ethical approval was granted by the hospital Human Research Ethics Committee.

RESULTS

In total, 144 thoracoscopic AtriClip procedures were conducted by a single surgeon from 2017 to 2022, 56 standalone and 88 concomitant. There was no mortality or major morbidities. A 100% success in complete LAA closure was observed, with 87% complete follow-up imaging. For patients that underwent standalone AtriClip after cessation of anticoagulation, no thromboembolic phenomena were seen in the 180 patient-years of follow-up.

CONCLUSIONS

This study demonstrates that thoracoscopic placement of AtriClip is safe and effective in achieving consistent and complete LAAO. Future randomised trials will be useful to compare outcomes with percutaneous devices.

Left Atrial Appendage Closure: Therapy Overview and Future Perspective

The left atrial appendage (LAA) has gained increasing attention in the field of cardiology as a potential site for intervention in patients with atrial fibrillation (AF) and an elevated risk of thromboembolic events. Left atrial appendage occlusion (LAAO) has emerged as a promising therapeutic strategy to mitigate the risk of stroke and systemic embolism, especially in individuals who are unsuitable candidates for long-term anticoagulation therapy. This review aims to provide a comprehensive analysis of the current state of LAAO, encompassing its anatomic considerations, procedural techniques, clinical outcomes, and future directions.

Morphological and functional assessment of the left atrial appendage in daily practice: a comprehensive approach using basic and advanced echocardiography with practical tips

Cardioembolic stroke is the most serious and life-threatening complication of atrial fibrillation (AF), with an associated mortality up to 30% at 12 months. Approximately 47% of thrombi in valvular AF and 91% of thrombi in nonvalvular AF are localized in the left atrial appendage (LAA). Therefore, identification or exclusion of LAA thrombi is critical in many clinical situations. It is essential to assess LAA morphology and function using imaging modalities (particularly echocardiography) before, during, and after interventional procedures such as AF ablation and LAA occlusion. This review article describes the anatomical, physiological, and pathological background of the LAA, followed by an assessment of different echocardiographic modalities. Many practical points are included to improve the diagnostic accuracy and to minimize errors during image acquisition and interpretation. In each clinical scenario where LAA is the crucial target, specific and essential information and parameters are collected.

A Comprehensive Review of Percutaneous and Surgical Left Atrial Appendage Occlusion

Atrial fibrillation (AF) is the most common arrhythmia worldwide, and is associated with a significant risk of thromboembolic events. Left atrial appendage occlusion (LAAO) has emerged as a promising alternative for patients with contraindications or intolerance to anticoagulant therapy. This review summarises the current evidence, indications, and technical advancements in surgical and percutaneous LAAO. Preprocedural planning relies on various imaging techniques, each with unique advantages and limitations. The existing randomised clinical trials and meta-analyses demonstrate favourable results for both percutaneous and surgical LAAO. Postprocedural management emphasises personalised anticoagulation strategies and comprehensive imaging surveillance to ensure device stability and detect complications. Future focus should be put on antithrombotic regimens, investigating predictors of device-related complications, and simplifying procedural aspects to enhance patient outcomes. In summary, LAAO is presented as a valuable therapeutic option for preventing AF-related thromboembolic events, with ongoing research aimed at refining techniques and improving patient care.

Efficiency of optimal fluoroscopic projection angle defined by computed tomography angiography for left atrial appendage closure

BACKGROUND

Left atrial appendage (LAA) closure (LAAC) procedures are conventionally performed using empirical fluoroscopic viewing angles. However, because the LAA is a highly variable anatomical structure, these angles cannot depict the LAA in the optimal position. The present study aimed to assess the efficiency of using a novel optimal fluoroscopic projection angle (OPA) for LAAC and to validate its feasibility.

METHODS

The OPAs of the derivation cohort were acquired using cardiac computed tomography angiography (CCTA) to assess its superiority for depicting LAA depth versus traditional working angles (TAs) of RAO 30°, CAU 20°. The practicability of OPA-guided LAAC was demonstrated by comparison between clinical data from the validation cohort and those from a propensity-score matched (PSM) control group, as well as randomized controlled studies investigating LAAC.

RESULTS

Of 705 patients in the derivation cohort, the median OPA was RAO 46°, CAU 31°. Compared with TA, the OPA depicted a longer mean (±SD) LAA depth (5.1 ± 4.4) mm and a larger orifice diameter (1.1 ± 1.1 mm), (P < 0.0001 for both). All 38 OPA-guided LAACs were successful, with a shorter mean procedure duration (42.9 ± 12.3 min versus [vs.] 107.2 ± 41.5 min; P < 0.0001) and reduced device consumption (1.08 vs. 1.5 per case), compared with the PSM control group. At the 3-month follow-up, the incidence of peri-device leak was 52.6% (20/38) detected by CCTA, with a mean leakage of 1.6 ± 0.8 mm.

CONCLUSION

By unfolding the LAA depth and orifice diameter for a better view, OPA demonstrated the potential to optimize LAAC procedural efficiency, although further larger-scale studies are required to confirm this.

Chinese guidelines for the diagnosis and management of atrial fibrillation

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, significantly impacting patients' quality of life and increasing the risk of death, stroke, heart failure, and dementia. Over the past two decades, there have been significant breakthroughs in AF risk prediction and screening, stroke prevention, rhythm control, catheter ablation, and integrated management. During this period, the scale, quality, and experience of AF management in China have greatly improved, providing a solid foundation for the development of the guidelines for the diagnosis and management of AF. To further promote standardized AF management, and apply new technologies and concepts to clinical practice timely and fully, the Chinese Society of Cardiology of Chinese Medical Association and the Heart Rhythm Committee of Chinese Society of Biomedical Engineering jointly developed the Chinese Guidelines for the Diagnosis and Management of Atrial Fibrillation. The guidelines comprehensively elaborated on various aspects of AF management and proposed the CHA2DS2‑VASc‑60 stroke risk score based on the characteristics of the Asian AF population. The guidelines also reevaluated the clinical application of AF screening, emphasized the significance of early rhythm control, and highlighted the central role of catheter ablation in rhythm control.

ACR Appropriateness Criteria® Preprocedural Planning for Left Atrial Procedures in Atrial Fibrillation

This document summarizes the relevant literature for the selection of preprocedural imaging in three clinical scenarios in patients needing endovascular treatment or cardioversion of atrial fibrillation. These clinical scenarios include preprocedural imaging prior to radiofrequency ablation; prior to left atrial appendage occlusion; and prior to cardioversion. The appropriateness of imaging modalities as they apply to each clinical scenario is rated as usually appropriate, may be appropriate, and usually not appropriate to assist the selection of the most appropriate imaging modality in the corresponding clinical scenarios. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Impact of left atrial appendage orifice diameter on the safety and efficacy of left atrial appendage closure using the LAmbre device

BACKGROUND

The diameter and shape of the left atrial appendage (LAA) orifices may influence occluder selection and the outcomes of left atrial appendage closure (LAAC) procedure. This study aimed to evaluate the impact of LAA orifice diameter on the safety and efficacy of LAAC using the LAmbre device.

METHODS

A total of 133 patients with nonvalvular atrial fibrillation (AF) who underwent LAAC with the LAmbre device between June 2018 and June 2020 were included in this study. The patients were categorized into two groups based on the maximal diameter of the LAA orifice: the large LAA group (n = 45) with a maximal orifice diameter of ≥31 mm, and the normal LAA group (n = 88) with a maximal orifice diameter of <31 mm. The study assessed periprocedural characteristics and long-term clinical follow-up.

RESULTS

Successful implantation of the LAmbre device was observed in all patients. The incidence of periprocedural peridevice leakage (PDL) was significantly higher in the large LAA group (P < 0.001), while the incidence of acute pericardial effusion (PE) during the procedure was comparable between the two groups (P = 1.000). After a mean follow-up period of 4.8 ± 1.7 years, three patients in the large LAA group developed delayed PE, while no patients in the normal LAA group did (P = 0.037). Additionally, a larger LAA maximal orifice diameter was associated with a higher prevalence of PDL (P = 0.001) and PE (including both acute and delayed PE) (P = 0.027). The optimal cutoff value of the LAA maximal orifice diameter for predicting PDL and PE after LAAC with the LAmbre device was determined to be 30 mm.

CONCLUSION

The findings suggest that the LAmbre device is a safe and feasible option for occluding the LAA, regardless of its orifice diameter. However, it is important to note that a larger LAA orifice diameter may increase the risk of PDL and delayed PE.

Atrial Thrombosis Prevalence Before Cardioversion or Catheter Ablation of Atrial Fibrillation: An Updated Systematic Review and Meta-Analysis of Direct Oral Anticoagulants Versus Vitamin K Antagonists

Left atrial or left atrial appendage thrombosis (LAT) is contraindicated for cardiac ablation (CA) or cardioversion (CV) of atrial fibrillation (AF). This study was aimed to compare the frequency of LAT detected by transesophageal echocardiography (TEE) before CA or CV in patients with AF treated with direct oral anticoagulants (DOACs) or vitamin K antagonists (VKAs). We searched PubMed, Scopus, Web of Science, and Cochran Library databases from inception through July 13, 2023 to select studies reporting data on LAT identification before CA or CV using TEE in patients with AF treated with DOACs or VKAs. Pooled odds ratios (ORs) with 95% confidence interval were calculated with a random-effects model. Studies retrieved were 50 (38 observational), 29 on CA, 15 on CV, and 6 on both procedures (17,096 patients on DOACs and 13,666 on VKAs). The overall prevalence of LAT was smaller in DOACs than in VKAs, with an OR of 0.66 (0.52 to 0.84), confirmed at sensitivity analysis and in most subgroups. This finding was consistent for the 3 most reported DOACs: the pooled OR for LAT was 0.68 (0.50 to 0.90) in apixaban, 0.67 (0.51 to 0.88) in dabigatran, 0.61 (0.43 to 0.89) in rivaroxaban, and 1.10 (0.74 to 1.64) in edoxaban (not significant). In conclusion, in this large meta-analysis in patients with AF, the prevalence of LAT by TEE evaluation performed before CV or CA appears lower in those treated with DOACs than in those on VKAs. Additional research may help in better understanding differences between these classes of anticoagulant drugs in the setting of protection against AF-related left atrial thrombotic formation.

A device-related fistula between coronary artery and left atrial appendage following left atrial appendage closure: Case presentation

INTRODUCTION

Left atrial appendage (LAA) closure (LAAC) is considered a viable alternative to anticoagulation therapy for stroke prevention in nonvalvular atrial fibrillation, we report a case with a less common shunt resulting from a device-related coronary artery-appendage fistula (CAAF) following LAAC.

METHODS AND RESULTS

A 67-year-old male with a history of LAAC was referred to our emergency room with recurrent chest pain and palpitations and was diagnosed with ischemic angina pectoris. Subsequent coronary angiography (CAG) revealed 70% in-stent restenosis and an abnormal shunt of contrast originating from the left circumflex artery (LCA) to the LAA tip which did not exist before. The restenosis was successfully dilated using a drug-coated balloon, the procedure was safely completed without pericardial effusion. The patient had been implanted with a LAmbre occluder (Lifetech Scientific Corp.) in the previous LAAC procedure. This occluder had a lobe-disk design, and the distal umbrella was not fully opened after release, particularly in the lower portion. This could make the hooks embedded on the umbrella contact the LAA wall more tightly, possibly resulting in microperforation and coincidental impingement of the LCA. The epicardial adipose and hyperplastic tissue then chronically wrapped the perforated site, prevented blood outflow into the epicardium, and ultimately formed a CAAF.

CONCLUSION

CAAF is a rare complication after LAAC but may be underestimated, especially for lobe-disk designed occluders. Therefore, CAG is perhaps necessary to detect this complication.

Lights and shadows on left atrial appendage occlusion: mind the gap in knowledge and think twice on long-term outcomes

Ischemic stroke prevention represents a crucial concern in health systems, being associated with high morbidity and mortality. Atrial fibrillation is associated with 15-20% of ischemic strokes, in the presence of thrombus in the left atrial appendage in 90% of patients with nonvalvular atrial fibrillation. Oral anticoagulation represents the standard of care. However, left atrial appendage occlusions have been developed for selected patients with nonvalvular atrial fibrillation. With regard to the latter, particularly, some important concerns have been raised on the selection of patients potentially amenable to the procedure, seemingly emphasizing a gap in knowledge, real-life clinical practice, and current management guidelines. In light of the recent evidence regarding the current indications for management of left atrial appendage in presence of nonvalvular atrial fibrillation, the purpose of this critical review is to highlight the blind spots of left atrial appendage occlusion indications, taking into account the evidence-based mid- to long-term outcomes. Apparently, many unsolved concerns and problems are still present, mainly including mid- and long-term device-related potential complications, the possibility of concurrent sources of embolization, ethical and economic issues. Furthermore, larger, well designed, long-term, multicentric, and more inclusive studies, as well as shared/integrated registries are needed, aiming at comparing direct oral anticoagulation with left atrial appendage occlusion in the long run.

Associations between 3D-based Left Atrial Volumetric and Blood Flow Parameters in a Single-Site Cohort of the Multi-Ethnic Study of Atherosclerosis

Purpose To investigate associations between left atrial volume (LAV) and function with impaired three-dimensional hemodynamics from four-dimensional flow MRI. Materials and Methods A subcohort of participants from the Multi-Ethnic Study of Atherosclerosis from Northwestern University underwent prospective 1.5-T cardiac MRI including whole-heart four-dimensional flow and short-axis cine imaging between 2019 and 2020. Four-dimensional flow MRI analysis included manual three-dimensional segmentations of the LA and LA appendage (LAA), which were used to quantify LA and LAA peak velocity and blood stasis (% voxels < 0.1 m/sec). Short-axis cine data were used to delineate LA contours on all cardiac time points, and the resulting three-dimensional-based LAVs were extracted for calculation of LA emptying fractions (LAEFtotal, LAEFactive, LAEFpassive). Stepwise multivariable linear models were calculated for each flow parameter (LA stasis, LA peak velocity, LAA stasis, LAA peak velocity) to determine associations with LAV and LAEF. Results This study included 158 participants (mean age, 73 years ± 7 [SD]; 83 [52.5%] female and 75 [47.4%] male participants). In multivariable models, a 1-unit increase of LAEFtotal was associated with decreased LA stasis (β coefficient, -0.47%; P < .001), while increased LAEFactive was associated with increased LA peak velocity (β coefficient, 0.21 cm/sec; P < .001). Furthermore, increased minimum LAV indexed was most associated with impaired LAA flow (higher LAA stasis [β coefficient, 0.65%; P < .001] and lower LAA peak velocity [β coefficient, -0.35 cm/sec; P < .001]). Conclusion Higher minimum LAV and reduced LA function were associated with impaired flow characteristics in the LA and LAA. LAV assessment might therefore be a surrogate measure for LA and LAA flow abnormalities. Keywords: Atherosclerosis, Left Atrial Volume, Left Atrial Blood Flow, 4D Flow MRI Supplemental material is available for this article. © RSNA, 2024.

Percutaneous left atrial appendage occlusion and risk of stroke, hospitalized bleeding and death in Medicare beneficiaries

PURPOSE

Among patients with atrial fibrillation (AF), a nonpharmacologic option (e.g., percutaneous left atrial appendage occlusion [LAAO]) is needed for patients with oral anticoagulant (OAC) contraindications. Among beneficiaries in the Medicare fee-for-service coverage 20% sample databases (2015-18) who had AF and an elevated CHA2DS2-VASc score, we assessed the association between percutaneous LAAO versus OAC use and risk of stroke, hospitalized bleeding, and death.

METHODS

Patients undergoing percutaneous LAAO were matched to up to five OAC users by sex, age, date of enrollment, index date, CHA2DS2-VASc score, and HAS-BLED score. Overall, 17 156 patients with AF (2905 with percutaneous LAAO) were matched (average ± SD 78 ± 6 years, 44% female). Cox proportional hazards model were used.

RESULTS

Median follow-up was 10.3 months. After multivariable adjustments, no significant difference for risk of stroke or death was noted when patients with percutaneous LAAO were compared with OAC users (HRs [95% CIs]: 1.14 [0.86-1.52], 0.98 [0.86-1.10]). There was a 2.94-fold (95% CI: 2.50-3.45) increased risk for hospitalized bleeding for percutaneous LAAO compared with OAC use. Among patients 65 to <78 years old, those undergoing percutaneous LAAO had higher risk of stroke compared with OAC users. No association was present in those ≥78 years.

CONCLUSION

In this analysis of real-world AF patients, percutaneous LAAO versus OAC use was associated with similar risk of death, nonsignificantly elevated risk of stroke, and an elevated risk of bleeding in the post-procedural period. Overall, these results support results of randomized trials that percutaneous LAAO may be an alternative to OAC use for patients with contraindications.

Chinese Guidelines for the Diagnosis and Management of Atrial Fibrillation

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, significantly impacting patients' quality of life and increasing the risk of death, stroke, heart failure, and dementia. Over the past two decades, there have been significant breakthroughs in AF risk prediction and screening, stroke prevention, rhythm control, catheter ablation, and integrated management. During this period, the scale, quality, and experience of AF management in China have greatly improved, providing a solid foundation for the development of guidelines for the diagnosis and management of AF. To further promote standardized AF management, and apply new technologies and concepts to clinical practice in a timely and comprehensive manner, the Chinese Society of Cardiology of the Chinese Medical Association and the Heart Rhythm Committee of the Chinese Society of Biomedical Engineering have jointly developed the Chinese Guidelines for the Diagnosis and Management of Atrial Fibrillation. The guidelines have comprehensively elaborated on various aspects of AF management and proposed the CHA2DS2-VASc-60 stroke risk score based on the characteristics of AF in the Asian population. The guidelines have also reevaluated the clinical application of AF screening, emphasized the significance of early rhythm control, and highlighted the central role of catheter ablation in rhythm control.

Computed Tomography to Exclude Cardiac Thrombus in Atrial Fibrillation-An 11-Year Experience from an Academic Emergency Department

BACKGROUND

Computed tomography (CT) could be a suitable method for acute exclusion of left atrial appendage thrombus (LAAT) prior to cardioversion of atrial fibrillation (AF) and atrial flutter (AFL) at the emergency department. Our aim was to present our experiences with this modality in recent years.

METHODS

This registry-based observational study was performed at the Department of Emergency Medicine at the Medical University of Vienna, Austria. We studied all consecutive patients with AF and AFL who underwent CT between January 2012 and January 2023 to rule out LAAT before cardioversion to sinus rhythm was attempted. Follow-ups were conducted by telephone and electronic medical records. The main variables of interest were the rate of LAAT and ischemic stroke at follow-up.

RESULTS

A total of 234 patients (143 [61%] men; median age 68 years [IQR 57-76], median CHA2DS2-VASc 2 [IQR 1-4]) were analyzed. Follow-up was completed in 216 (92%) patients after a median of 506 (IQR 159-1391) days. LAAT was detected in eight patients (3%). A total of 163 patients (72%) in whom LAAT was excluded by CT were eventually successfully cardioverted to sinus rhythm. No adverse events occurred during their ED stay. All patients received anticoagulation according to the CHA2DS2-VASc risk stratification, and no patient had suffered an ischemic stroke at follow-up, resulting in an incidence risk of ischemic strokes of 0% (95% CI 0.0-1.2%).

CONCLUSION

LAAT was rare in patients admitted to the ED with AF and AFL who underwent cardiac CT prior to attempted cardioversion. At follow-up, no patient had suffered an ischemic stroke. Prospective studies need to show whether this strategy is suitable for the acute treatment of symptomatic AF in the emergency setting.

Aetiology, Diagnosis and Treatment of Arterial Occlusions of the Retina-A Narrative Review

Arterial occlusions of the retina are potentially sight-threatening diseases which often result in profound visual loss. The aim of this narrative review is to provide an overview of the aetiology, discuss major risk factors, describe the management and systemic assessments and evaluate existing therapies. For this review, an extensive literature search in PubMed was performed. Emboli from the heart or the carotid arteries can cause ophthalmic artery occlusion (OAO), central retinal artery occlusion (CRAO) and branch retinal artery occlusion (BRAO). Most patients with arterial occlusions have vascular risk factors such as arterial hypertension, hyperhomocysteinaemia, carotid stenosis and atrial fibrillation, which also increase the risk of cerebral stroke and myocardial infarction. Therapies such as ocular massage, thrombolysis and anterior chamber paracentesis have been suggested but are still equivocal. However, it is evident that retinal artery occlusion should be immediately treated and accompanied by interdisciplinary collaboration, since early diagnosis and the proper treatment of possible risk factors are important to reduce the risk of further damage, recurrences, other vascular diseases and mortality.

The impact of contrast retention on thrombus formation risks in patients with atrial fibrillation: A numerical study

Background

Contrast retention (CR) is an important predictor of left atrial appendage thrombus (LAAT) and stroke in patients with non-valvular atrial fibrillation (AF). We sought to explore the underlying mechanisms of CR using computational fluid dynamic (CFD) simulations.

Methods

A total of 12 patients with AF who underwent both cardiac computed tomography angiography (CTA) and transesophageal echocardiography (TEE) before left atrial appendage occlusion (LAAO) were included in the study. The patients were allocated into the CR group or non-CR group based on left atrial appendage (LAA) angiography. Patient-specific models were reconstructed to evaluate time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), relative residence time (RRT), and endothelial cell activation potential (ECAP). Additionally, the incidence of thrombosis was predicted using residence time (RT) at different time-points.

Results

TAWSS was lower [median (Interquartile Range) 0.27 (0.19-0.47) vs 1.35 (0.92-1.79), p < 0.001] in LAA compared to left atrium. In contrast, RRT [1438 (409.70-13869) vs 2.23 (1.81-3.14), p < 0.001] and ECAP [122.70 (30.01-625.70) vs 0.19 (0.16-0.27), p < 0.001)] was higher in the LAA. The patients in the CR group had significantly higher RRT [(mean ± SD) 16274 ± 11797 vs 639.70 ± 595.20, p = 0.009] and ECAP [610.80 ± 365.30 vs 54.26 ± 54.38, p = 0.004] in the LAA compared to the non-CR group. Additionally, patients with CR had a wider range of thrombus-prone regions [0.44(0.27-0.66)% vs 0.05(0.03-0.27)%, p = 0.009] at the end of the 15th cardiac cycle.

Conclusions

These findings suggest that CR might be an indicator of high-risk thrombus formation in the LAA. And CT-based CFD simulation may be a feasible substitute for the evaluation of LAA thrombotic risk in patients with AF, especially in patients with CR.

Left Atrial Appendage Autograft for Anomalous Origin of Left Coronary Artery From Pulmonary Artery

A novel interposition technique is presented in which a pediatric patient underwent reimplantation of the anomalous origin of the left coronary artery from the pulmonary artery into the aorta by creation of an extension using an autograft of the left atrial appendage. The advantage of this technique is that the autograft remains patent and lies anatomically without tension over the pulmonary artery as demonstrated in the follow-up computed tomography angiogram.

Long-term outcomes of left atrial appendage closure with or without concomitant pulmonary vein isolation:a propensity score matching analysis based on CLACBAC study

BACKGROUND

The combined procedure of left atrial appendage closure (LAAC) with concomitant pulmonary vein isolation (PVI) has demonstrated its efficacy and safety. However, there is still a lack of comparative investigations regarding the long-term benefits of the combined procedure when compared to LAAC alone. Our study aims to assess the long-term outcomes of combined procedure of LAAC with concomitant PVI in comparison with a propensity matched LAAC alone group.

METHODS

Propensity score matching (PSM) was employed to rectify covariate imbalances, resulting in the inclusion of 153 comparable patients from the initial cohort of 333 non-valvular atrial fibrillation (AF) patients. Clinical outcomes, encompassing thrombotic events, major cardiocerebrovascular adverse events (MACCE), re-hospitalization due to cardiovascular disease (CVD), and atrial tachycardia (AT), were juxtaposed between the two groups. Bleeding events and peri-device complications, such as residual flow, device-related thrombus, and device replacement, were also compared. Additionally, a patients group underwent PVI alone was included for comparing AF recurrence rates between the PVI alone group and the combined group.

RESULTS

Following PSM, 153 patients (mean age 70.3 ± 8.9, 62.7% men) were included, with 102 undergoing the combined procedure and 51 undergoing LAAC alone. No significant differences were found in baseline characteristics between the two groups. The mean follow-up time was 37.6 ± 7.9 months, and two patients were lost to follow-up in the combined procedure group. Thrombotic events were observed in 4 (7.8%) patients in the LAAC alone group and 4 (4.0%) in the combined group (Log-rank p = 0.301). The proportion of patients experiencing MACCE, re-hospitalization due to CVD, and AT between the two groups was comparable, as were bleeding events and peri-device complications. Among patients from the combined procedure group without AF recurrence, a significant difference was noted in prior-procedure left ventricular ejection fraction (LVEF) and LVEF at the 12th month after the procedure (57.2% ± 7.1% vs. 60.5% ± 6.5%, p = 0.002).

CONCLUSION

The concomitant PVI and LAAC procedure did not increase procedure-related complications, nor did it confer significant benefits in preventing thrombotic events or reducing other cardiovascular events. However, the combined procedure improved heart function, suggesting potential long-term benefits.

Preprocedural Planning of Left Atrial Appendage Occlusion: A Review of the Use of Additive Manufacturing

Stroke is a significant public health problem, with non-valvular atrial fibrillation (NVAF) being one of its main causes. This cardiovascular arrhythmia predisposes to the production of intracardiac thrombi, mostly formed in the left atrial appendage (LAA). When there are contraindications to treatment with oral anticoagulants, another therapeutic option to reduce the possibility of thrombus formation in the LAA is the implantation of an occlusion device by cardiac catheterization. The effectiveness of LAA occlusion is dependent on accurate preprocedural device sizing and proper device positioning at the LAA ostium, to ensure sufficient device anchoring and avoid peri-device leaks. Additive manufacturing, commonly known as three-dimensional printing (3DP), of LAA models is beginning to emerge in the scientific literature to address these challenges through procedural simulation. This review aims at clarifying the impact of 3DP on preprocedural planning of LAA occlusion, specifically in the training of cardiac surgeons and in the assessment of the perfect adjustment between the LAA and the biomedical implant.

Three-dimensional high-definition live tissue virtual dissection of mirror-image dextrocardia with thoracic-abdominal discordance in a fetus

Three-dimensional virtual dissection using high-definition live tissue rendering ultrasound tool of a 23-week gestation fetus with situs solitus, mirror image dextrocardia, ventricular septal defect, aortic override, and pulmonary atresia.

Pattern of Endothelialization in Left Atrial Appendage Occluder by Optic Coherence Tomography: A Pilot Study

BACKGROUND

Implantation of the left atrial appendage occluder (LAAO) has been proven to prevent stroke effectively in patients with atrial fibrillation who cannot tolerate anticoagulants. Incomplete endothelization of LAAO may cause device-related thrombus, and currently no good image modality exists to clearly see LAAO endothelialization. We aimed to use coronary optic coherence tomography (OCT) to visualize LAAO endothelialization.

METHODS AND RESULTS

We enrolled 14 patients (72.8±9.4 years old) undergoing pulmonary vein isolation with a preexisting LAAO implanted more than 1 year ago (5 Watchman and 9 Amulet). After pulmonary vein isolation, we did OCT via steerable sheath and coronary guiding catheter to adjust OCT probe location and injected contrast medium to visualize the LAAO surface. In vitro testing was also performed to see the bare occluder. In vitro OCT showed the surface of the bare device as an interrupted granule pattern, which included the Watchman surface polytetrafluoroethylene membrane string, Amulet disc metal strut, and inner polytetrafluoroethylene membrane string. In the implanted Watchman, OCT showed endothelialization as a smooth surface layer with noninterrupted coarser granules. In the implanted Amulet, OCT showed endothelialization as thin (early) or thick (late) endothelialization layer covering struts with OCT shadows. Among patients with Watchman, 2 showed no, 2 early, and 1 complete endothelialization. Among patients with Amulet, 2 showed no, 3 early, and 4 late endothelialization.

CONCLUSIONS

We demonstrated the feasibility of OCT to visualize LAAO endothelization with high resolution. Further studies are needed to determine antithrombotic regimens if incomplete endothelization is detected. A new OCT catheter may be designed specifically for LAAO.

Morphogenesis of the pulmonary vein and left atrial appendage in human embryos and early fetuses

The left atrium wall has several origins, including the body, appendage, septum, atrial-ventricular canal, posterior wall, and venous component. Here, we describe the morphogenesis of left atrium based on high-resolution imaging (phase-contrast X-ray computed tomography and magnetic resonance imaging). Twenty-three human embryos and 19 fetuses were selected for this study. Three-dimensional cardiac images were reconstructed, and the pulmonary veins and left atrium, including the left atrial appendage, were evaluated morphologically and quantitatively. The positions of the pericardial reflections were used as landmarks for the border of the pericardial cavity. The common pulmonary vein was observed in three specimens at Carnegie stages 17-18. The pericardium was detected at the four pulmonary veins (left superior, left inferior, right superior, and right inferior pulmonary veins) at one specimen at Carnegie stage 18 and all larger specimens, except the four samples. Our results suggest that the position of the pericardial reflections was determined at two pulmonary veins (right and left pulmonary vein) and four pulmonary veins almost simultaneously when the dorsal mesocardial connection between the embryo and heart regressed. The magnetic resonance images and reconstructed heart cavity images confirmed that the left atrium folds were present at the junction between the body and venous component. Three-dimensional reconstruction showed that the four pulmonary veins entered the dorsal left atrium tangentially from the lateral to the medial direction. More specifically, the right pulmonary veins entered at a greater angle than the left pulmonary veins. The distance between the superior and inferior pulmonary veins was shorter than that between the left and right pulmonary veins. Three-dimensional reconstruction showed that the venous component increased proportionally with growth. No noticeable differences in discrimination between the right and left parts of the venous component emerged, while the junction between the venous component and body gradually became inconspicuous but was still recognizable by the end of the observed early fetal period. The left superior pulmonary vein had the smallest cross-sectional area and most flattened shape, whereas the other three were similar in area and shape. The left atrial appendage had a large volume in the center and extended to the periphery as a lobe-like structure. The left atrial appendage orifice increased in the area and tended to become flatter with growth. The whole left atrium volume^(1/3) increased almost proportionally with growth, parallel to the whole heart volume. This study provided a three-dimensional and quantitative description of the developmental process of the left atrium, comprising the venous component and left atrial appendage formation, from the late embryonic to the early fetal stages.

Use of Computed Tomography for Left Atrial Appendage Occlusion Procedure Planning and Post-Procedure Assessment

Transcatheter left atrial appendage occlusion (LAAO) is an alternative to systemic anticoagulation in patients with non-valvular atrial fibrillation with increased risk for thromboembolic events. Pre- and post-procedural imaging is essential for technical success, allowing practitioners to identify contraindications, select appropriate devices, and recognize procedural complications. Although transesophageal echocardiography has traditionally served as the preeminent imaging modality in LAAO, cardiac computed tomography imaging has emerged as a noninvasive surrogate given its excellent isotropic spatial resolution, multiplanar reconstruction capability, rapid temporal resolution, and large field of view.

Midterm follow-up after computed tomography angiography planned left atrial appendage closure

BACKGROUND

While studies have shown the advantages of computed tomography angiography (CTA) over transesophageal echocardiography (TEE) in left atrial appendage closure (LAAC) preprocedural planning for WATCHMAN™ legacy and FLX devices, there has been no reported long-term data for this approach.

OBJECTIVES

We sought to evaluate long-term outcomes using CTA-based preprocedural planning for LAAC using the WATCHMAN™ device.

METHODS

A prospective analysis of 231 consecutive patients who underwent LAAC in a single, large academic hospital in the United States was conducted over a 5-year period. CTA-guided preprocedural planning was performed in all. Procedural success, adverse events, length of procedure, number of devices used, and length of stay were evaluated. Rates of death, cerebral embolism, systemic embolism, and major and minor bleeding were recorded. Adjusted predicted stroke and major bleeding rates were derived from CHA2DS2-Vasc and HAS-BLED scores, respectively.

RESULTS

From January 26, 2017, to November 23, 2021, 231 patients underwent LAAC with CTA preprocedural planning by two operating physicians. The mean age of patients was 76.5 ± 8.4. 59.7% of patients were male. Mean CHA2DS2VASc and HAS-BLED scores were 4.5 ± 1.4 and 3.9 ± 0.9, respectively. All procedures were performed with intracardiac echo (100%). The procedural success rate was 99.1%. The CTA sizing strategy accurately predicted the implant size in 93.5% of patients. Mean number of devices used was 1.10 ± 0.3. Peri-procedural complication rate was 2.2%. 6 patients were lost to follow-up. Mean follow-up was 608.94 days with a total of 377.04 patient years. Median follow-up period of 368 days (interquartile range: 209-1067 days). There were 51 deaths from all causes (13.52 per 100 patient-years), 10 cases of cerebral embolism (2.65 per 100 patient-years), 2 cases of systemic embolism (0.53 per 100 patient-years), 17 cases of major bleeding (4.50 per 100 patient-years), and 31 cases of minor bleeding (8.2 per 100 patient-years). All-cause mortality at 1, 2, and 3 years was 12.7%, 20.9%, and 29.2%, respectively. CV event rates at 1, 2, and 3 years were 2.1%, 6.6%, and 10.5%, respectively.

CONCLUSIONS

CTA-based preprocedural planning is accurate in predicting device size for LAAC and associated with excellent clinical outcomes at 5 years.

Intracardiac echocardiography is a promising strategy for guiding closure of the left atrial appendage

Background and Aims

Percutaneous transcatheter left atrial appendage (LAA) closure (LAAC) is an effective approach for preventing ischemic stroke in nonvalvular atrial fibrillation patients. Intracardiac echocardiography (ICE), a new imaging modality, is a promising strategy for guiding LAAC. This review highlights the various strategies for ICE-guided-LAAC as an option for clinical policy.

Methods

A comprehensive literature search was conducted of PubMed, ScienceDirect, Ovid Web of Science, SpringerLink, and other notable databases to identify recent peer-reviewed clinical trials, reviews, and research articles related to ICE and its application in the guidance of LAAC.

Results

Various methods are used to evaluate the spatial structure and dimensions of the LAA. The main techniques for guiding LAAC are transesophageal echocardiography (TEE), cardiac computed tomography (CTA), and ICE. Among these techniques, the advantages of ICE typically include (1) multiangle and real-time assessment of intracardiac structure, (2) a reduction in procedural fluoroscopy, (3) reduced operation time and improved workflow in the catheterization laboratory, and (4) the avoidance of general anesthesia and the early detection of complications.

Conclusion

ICE is a promising strategy for the guidance of LAAC. Among the most advanced and recent technological innovations in cardiovascular imaging in general and volume imaging in particular, ICE offers greater efficacy and safety.

The Left Atrial Appendage and Atrial Fibrillation-A Contemporary Review

In patients with atrial fibrillation, the left atrial appendage may serve as the site of thrombus formation due to stasis that occurs within the appendage because of its shape and trabeculations. Although thrombus formation can be reduced by using anticoagulants, this may be contraindicated in some patients. The need for a better alternative treatment prompted the study of left atrial appendage occlusion for thromboembolism prophylaxis. Due to this, procedures that excise or occlude the left atrial appendage have gained attention because of their ability to prevent thromboembolic events. This article provides a comprehensive review of the left atrial appendage and its associated procedures' clinical utility.