Stroke prevention in atrial fibrillation: atrial appendage closure

A highly-detailed anatomical study of left atrial auricle as revealed by in-vivo computed tomography

The left atrial auricle (LAA) is the main source of intracardiac thrombi, which contribute significantly to the total number of stroke cases. It is also considered a major site of origin for atrial fibrillation in patients undergoing ablation procedures. The LAA is known to have a high degree of morphological variability, with shape and structure identified as important contributors to thrombus formation. A detailed understanding of LAA form, dimension, and function is crucial for radiologists, cardiologists, and cardiac surgeons. This review describes the normal anatomy of the LAA as visualized through multiple imaging techniques such as computed tomography (CT), magnetic resonance imaging (MRI), and echocardiography. Special emphasis is devoted to a discussion on how the morphological characteristics of the LAA are closely related to the likelihood of developing LAA thrombi, including insights into LAA embryology.

5-Year Experience of In-Hospital Outcomes After Percutaneous Left Atrial Appendage Closure in Germany

OBJECTIVES

The aim of this study was to evaluate 5-year in-hospital trends and safety outcomes of left atrial appendage (LAA) closure in the German nationwide inpatient sample.

BACKGROUND

The safety and efficacy of percutaneous LAA closure have been demonstrated in randomized trials and prospective cohort studies, but results from large samples are missing.

METHODS

Data on patient characteristics and in-hospital safety outcomes for all percutaneous LAA closures performed in Germany between 2011 and 2015 were analyzed. Overall, 15,895 inpatients were included.

RESULTS

The annual number of LAA occlusions increased from 1,347 in 2011 to 4,932 in 2015 (β = 1.00; 95% confidence interval [CI]: 0.95 to 1.01; p < 0.001), with a nonsignificant uptrend of in-hospital mortality (from 0.5% in 2011 to 0.9% in 2015; β = 0.01; 95% CI: -0.09 to 0.32; p = 0.271). Patient characteristics shifted toward older age and higher prevalence of comorbidities such as heart failure, chronic obstructive pulmonary disease, and chronic renal insufficiency over time. Important independent predictors of in-hospital mortality were cancer (odds ratio [OR]: 2.49; 95% CI: 1.00 to 6.12; p = 0.050), heart failure (OR: 2.42; 95% CI: 1.72 to 3.41; p < 0.001), stroke (OR: 5.39; 95% CI: 2.76 to 10.53; p < 0.001), acute renal failure (OR: 13.28; 95% CI: 9.08 to 19.42; p < 0.001), pericardial effusion (OR: 5.65; 95% CI: 3.76 to 8.48; p < 0.001), and shock (OR: 45.11; 95% CI: 31.01 to 65.58; p < 0.001).

CONCLUSIONS

The use of percutaneous LAA closure increased 3.6-fold from 2011 to 2015, with a nonsignificant uptrend of in-hospital mortality rate in this real-world setting. Important predictors of in-hospital death were acute renal failure, pericardial effusion, and ischemic stroke during hospitalization.

Syncope in the German Nationwide inpatient sample - Syncope in atrial fibrillation/flutter is related to pulmonary embolism and is accompanied by higher in-hospital mortality

AIMS

Syncope is a common phenomenon in the general population. Although most of the causes are of benign origin, some comorbidities are accompanied by high mortality. We aimed to compare the in-hospital mortality of patients with syncope related to different comorbities and investigate the impact of syncope in patients with atrial fibrillation/flutter (AF).

METHODS

The nationwide inpatient sample of Germany of the years 2011-2014 was used for this analysis. Patients with syncope (ICD-code R55) were stratified by presence of selected comorbidities. Additionally, AF patients with and without syncope were compared. Incidence of syncope and in-hospital mortality were calculated. Syncope as a predictor of adverse outcome in AF patients was investigated.

RESULTS

In total, 1,628,859 hospitalizations of patients with syncope were identified; incidence was 504.6/100,000 citizens/year with case-fatality rate of 1.6%. Patients with syncope revealed frequently comorbidities as AF, heart failure and pneumonia. In-hospital mortality was high in syncope patients with pulmonary embolism (PE, 13.0%), pneumonia (12.8%), myocardial infarction (MI, 9.7%) and stroke (8.5%). We analysed 1,106,019 hospitalizations (52.9% females, 54.9% aged > 70 years) of patients with AF (2011-2014). Among these, 23,694 (2.1%) were coded with syncope and 0.7% died. Syncope had no significant impact on in-hospital mortality (OR 1.04, 95%CI 0.92-1.17, P = .503) independently of age, sex and comorbidities, but was associated with PE (OR 1.83, 95%CI 1.42-2.36, P < .001), MI (OR 1.68, 95%CI 1.48-1.90, P < .001), stroke (OR 1.66, 95%CI 1.42-1.94, P < .001) and pneumonia (OR 1.26, 95%CI 1.16-1.37, P < .001).

CONCLUSIONS

Syncope is a frequent cause for referrals in hospitals. While the overall in-hospital mortality rate is low (<2%), syncope in coprevalence with PE, pneumonia, MI and stroke showed a mortality rate > 8%. Syncope in AF patients had no independent impact on in-hospital mortality.

Impact of atrial fibrillation on in-hospital mortality of ischemic stroke patients and identification of promoting factors of atrial thrombi - Results from the German nationwide inpatient sample and a single-center retrospective cohort

Ischemic stroke is one of the leading causes of death and disability. Atrial fibrillation (AF) is a well-recognized risk factor for ischemic stroke.We aimed to investigate the impact of AF on in-hospital mortality of ischemic stroke patients and to identify parameters associated with intra-cardiac thrombogenic material.Patients were selected by screening the nationwide sample for ischemic stroke by ICD-Code (I63), stratified for AF. In this cohort, the association between in-hospital deaths and AF was investigated.In a second study, we performed a retrospective analysis of patients who underwent transesophageal echocardiography (TEE) for various reasons, assigned these to 2 groups based on the heart-rhythm (sinus-rhythm [SR] vs AF) and examined associations between clinical and echocardiographic parameters and intra-cardiac thrombogenic material.The Nationwide sample comprised 292,401 inpatients (48.5% females) with ischemic stroke. Incidence was 360 per 100,000 citizens, with an age-dependent increase. In-hospital mortality rate was 8.2%; AF patients had 1.85-fold higher mortality rate (12.1% vs 6.5%).In the retrospective study, 219 patients (median age 67 [59.1-77.3] years, 39.3% females) were included: 115 patients with AF (median age 71 [59.0-78.0] years, 41.7% females) and 104 patients (median age 68 [56.3-76.8] years, 36.5% females) with SR. Solid thrombus or spontaneous-echo-contrast) was detected in 16 TEEs. Atrial dimensions were significantly enlarged in AF patients. Age, blood-flow velocity in LAA, LAA diameters, atrial areas, AF, and CHA2DS2-VASc-score were associated with thrombogenic material.Incidence of ischemic stroke increased with age. AF was connected with higher stroke mortality. Presence of intra-cardiac thrombogenic material was associated with AF and most CHA2DS2-VASc-score factors. AF was associated with larger atrial dimensions and larger cavities favored thrombogenic material.

Percutaneous closure of the left atrial appendage for stroke prevention in atrial fibrillation: an alternative to lifelong anticoagulation?

Atrial fibrillation is an important risk factor for thromboembolic stroke and it significantly increases the risk of stroke. The left atrial appendage (LAA) is the most common site of thrombus formation in nonvalvular atrial fibrillation, and the recent applications of percutaneous LAA closure devices offer a promising alternative for patients who are unable to tolerate lifelong anticoagulation. Critical care nurses who understand the procedures and are familiar with the various devices used for LAA closure will be well prepared to provide optimum care and appropriate education for these patients.

STAF score is a new simple approach for diagnosing cardioembolic stroke

BACKGROUND AND PURPOSE

Detecting cardioembolic stroke soon after acute cerebral ischemia has a major impact on secondary stroke prevention. Recently, the Score for the Targeting of Atrial Fibrillation (STAF) was introduced to identify stroke patients at risk of atrial fibrillation. However, whether the STAF score could be a useful approach to differentiate cardioembolic stroke from other stroke subtypes is unclear.

METHODS

Consecutive patients with acute ischemic stroke that were admitted to our stroke center were enrolled. Each patient was assessed (age, baseline National Institutes of Health Stroke Scale, left atrial dilatation and absence of vascular etiology) to calculate the STAF score. A follow-up visit was conducted for each patient during hospitalization to determine the diagnosed stroke etiology according to the Trial of Org 10172 in Acute Stroke Treatment criteria.

RESULTS

The median and interquartile range of the STAF score was significantly higher in the cardioembolic than in the non-cardioembolic group [6 (2) vs. 2 (3), p < 0.001]. The discriminating ability of the STAF score model was good as demonstrated by the receiver operating characteristic curve. The area under the curve (AUC) of STAF score (AUC = 0.98; 95% CI, 0.96-0.99) was significantly greater than B-type natriuretic peptide (AUC = 0.87; 95% CI, 0.83-0.91) (p < 0.05). The optimal STAF cut-off value was ≥ 5, which diagnosed cardioembolic stroke with a sensitivity of 90% and specificity of 95%.

CONCLUSIONS

The STAF score is a simple and accurate tool that can discriminate the cardioembolic stroke from other types during hospitalization for acute ischemic stroke.

A Review Of The Relevant Embryology, Pathohistology, And Anatomy Of The Left Atrial Appendage For The Invasive Cardiac Electrophysiologist

The three-dimensional morphology of the left atrial appendage provides the substrate for thrombus generation, and is a harbinger for embolic material due to its direct connection to the left-sided circulation. Appreciating the development of the appendage from mesodermal layer to its adult form provides the basis to improve exclusion from the atrial circulation, and thereby can lead to a significant reduction in stroke risk. This process also provides insight into the role of the left atrial appendage as an endocrine organ, its involvement in fluid homeostasis, and its connection to the autonomic nervous system. Knowledge of the surrounding structural arrangement is critical to identify landmarks from both an endocardial and epicardial perspective to improve targeted device placement. Furthermore, correlation of the left atrial appendage body, neck, and ostium to the surrounding anatomy can also improve both procedural efficacy and safety. In addition, a working knowledge of the regional anatomy adds a prudent degree of awareness for procedural complications, and allows for early identification and timely intervention as these situations arise. A detailed understanding of the left atrial appendage embryology, histology, and gross anatomy is imperative to identify the correct device and approach for each individual patient. In addition, this increased awareness can identify areas that are in need of further innovation, and thus provide the ability to adapt and refine existing technologies to overcome pitfalls currently facing catheter-based approaches.

Percutaneous closure of the left atrial appendage for thromboembolic prevention in atrial fibrillation

Atrial fibrillation is a common arrhythmia in clinical practice. It is associated with high morbidity and mortality due to its thromboembolic potential, which makes thromboembolic prevention particularly important. Warfarin has been the first-line therapy for this purpose, but it has various limitations and is often contraindicated or underutilized. The fact that thrombi are frequently located in the left atrial appendage in atrial fibrillation led to the development of percutaneous closure for thromboembolic prevention. This article examines the current evidence on percutaneous closure of the left atrial appendage by reviewing the results of the numerous clinical trials on the technique.

Ineligibility for anticoagulation in patients with atrial fibrillation

Although anticoagulation therapy markedly reduces the risk of stroke in patients with atrial fibrillation, up to 50% of these patients are deemed ineligible for anticoagulation. In this manuscript we provide a framework to assess the net clinical benefit of anticoagulation in patients with atrial fibrillation with an increased risk of bleeding. We also review recent data related to the novel oral anticoagulants targeting thrombin or factor Xa, and discuss how the introduction of these agents raises the distinction between eligibility for vitamin K antagonist therapy specifically, and eligibility for anticoagulation in general.

Left atrial appendage occlusion and ligation devices: what is available, how to implement them, and how to manage and avoid complications

OPINION STATEMENT

Atrial fibrillation (AF) is the most common cardiac arrhythmia worldwide, and it is associated with an elevated risk of thromboembolic events, including ischemic stroke. Evidence suggests that at least 90 % of left atrial thrombi discovered in patients with AF are localized to the left atrial appendage (LAA). Surgical ligation or excision of the LAA is considered the standard of care in patients who undergo mitral valve surgery or as an adjunct to a surgical Maze procedure for treatment of AF. In addition, in selected patients with AF and an elevated risk of thromboembolic events, particularly in those with contraindication to oral anticoagulation (OAC) therapy, it is reasonable to consider LAA exclusion to offer protection against ischemic stroke and other embolic complications. This can be achieved through a number of different strategies, including surgical amputation or ligation of the LAA, percutaneous endocardial occlusion of the LAA by deployment of occlusive devices, and also ligation of the LAA via a closed-chest, percutaneous, epicardial catheter-based approach in select patients. Although results from several recent percutaneous LAA closure and ligation studies are highly promising, the evidence for long-term efficacy and safety is insufficient to presently recommend this approach to all patients other than those in whom long-term OAC is contraindicated. Future randomized studies are required to further address the long-term safety and efficacy of these therapeutic options. Finally, the role for LAA occlusion and ligation seems less clear in patients who undergo successful catheter ablation of AF, since at least in a subgroup of these patients antiplatelet therapy alone has been shown to be sufficient.

Left atrial appendage occlusion: pilot study of a fourth-generation, minimally invasive device

OBJECTIVE

Exclusion of the left atrial appendage is proposed to reduce the risk of stroke in patients with atrial fibrillation. The aim of this study was to evaluate the feasibility and efficacy of a fourth-generation atrial exclusion device developed for minimally invasive applications.

METHODS

The novel atrial exclusion device consists of two polymer beams and two elastomeric bands that connect the two beams at either end. Fifteen mongrel dogs were implanted with the device at the base of the left atrial appendage through a median sternotomy and were evaluated at 30 (n = 7), 90 (n = 6), and 180 (n = 2) days after implantation by epicardial echocardiography, left atrial and coronary angiography, gross pathology, and histology.

RESULTS

Left atrial appendage exclusion was completed without hemodynamic instability. Coronary angiography revealed that the left circumflex artery was patent in all cases. A new endothelial tissue layer developed, as expected, on the occluded orifice of the left atrium.

CONCLUSIONS

This novel atrial exclusion device achieved easy, reliable, and safe exclusion of the left atrial appendage, with favorable histological results in a canine model for up to 6 months. Clinical application could provide a new therapeutic option for reducing the risk of stroke in patients with atrial fibrillation.

The impact of CHADS2 score on late stroke after the Cox maze procedure

OBJECTIVE

The Heart Rhythm Society, European Heart Rhythm Association, and European Cardiac Arrhythmia Society jointly recommend indefinite warfarin anticoagulation in patients with CHADS2 (congestive heart failure, hypertension, age, diabetes, and stroke) score of at least 2 who have undergone ablation for atrial fibrillation. This study determined the impact of CHADS2 score on risk of late stroke or transient ischemic attack after the performance of a surgical Cox maze procedure.

METHODS

A retrospective review of 433 patients who underwent a Cox maze procedure at our institution was conducted. Three months after surgery, warfarin was discontinued regardless of CHADS2 score if the patient showed no evidence of atrial fibrillation, was off antiarrhythmic medications, and had no other indication for anticoagulation. A follow-up questionnaire was used to determine whether any neurologic event had occurred since surgery.

RESULTS

Follow-up was obtained for 90% of the study group (389/433) at a mean of 6.6 ± 5.0 years. Among these patients, 32% (125/389) had a CHADS2 score of at least 2, of whom only 40% (51/125) remained on long-term warfarin after surgery. Six patients had late neurologic events (annualized risk of 0.2%). Neither CHADS2 score nor warfarin anticoagulation was significantly associated with the occurrence of late neurologic events. Among the individual CHADS2 criteria, both diabetes mellitus and previous stroke or transient ischemic attack were predictive of late neurologic events.

CONCLUSIONS

The risk of stroke or transient ischemic attack in patients after a surgical Cox maze procedure was low and not associated with CHADS2 score or warfarin use. Given the known risks of warfarin, we recommend discontinuation of anticoagulation 3 months after the procedure if the patient has no evidence of atrial fibrillation, has discontinued antiarrhythmic medications, and is without any other indication for systemic anticoagulation.