Cardioversion from atrial fibrillation without prolonged anticoagulation with use of transesophageal echocardiography to exclude the presence of atrial thrombi

Cost-effectiveness of left atrial appendage occlusion during cardiac surgery in France: An economic evaluation based on the LAAOS III study

OBJECTIVES

Left atrial appendage occlusion during cardiac surgery is a therapeutic option for stroke prevention in patients with atrial fibrillation. The effectiveness and safety of left atrial appendage occlusion have been evaluated in several studies, including the LAAOS-III trial. While these studies have demonstrated efficacy and safety, the long-term economic impact of this surgical technique has not yet been assessed. Here, we aimed to evaluate the cost-effectiveness and cost-utility of left atrial appendage occlusion during cardiac surgery over a long-term time horizon.

METHODS

Our study was based on a model representing an hypothetical cohort with the same characteristics as LAAOS-III trial patients. We modelled the incidence of ischemic strokes and systemic embolisms in each intervention arm: "occlusion" and "no-occlusion," using a one-month cycle length with a 20-year time horizon. Regarding occlusion devices, sutures, staples, or an approved surgical occlusion device (AtriClip™-AtriCure, Ohio, USA) could be used.

RESULTS

Our model generated an average cost savings of 607 euros per patient and an incremental gain of 0.062 quality-adjusted life years (QALYs), resulting an incremental cost-utility ratio (ICUR) of €-9,775/QALY. The scenario analysis in which occlusion was systematically performed using the AtriClip™ device generated an ICUR of €3,952/QALY gained.

CONCLUSIONS

In the base-case analysis, the strategy proved to be more effective and less costly, confirming left atrial appendage occlusion during cardiac surgery as an economically dominant strategy. The scenario analysis also appeared cost-effective, although it did not result in cost savings. This study provides a new perspective on the assessment of the cost-effectiveness of these techniques.

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.

Transesophageal Echocardiogram Before Cardioversion in Atrial Fibrillation Patients

Transesophageal echocardiography (TEE) offers an invaluable, non-invasive avenue for diagnosing and managing various cardiac conditions, including atrial fibrillation (AF). As the most common cardiac arrhythmia, AF affects millions and can lead to severe complications. Cardioversion, a procedure to restore the heart's normal rhythm, is frequently conducted on AF patients resistant to medication. Due to inconclusive data, TEE's utility prior to cardioversion in AF patients remains ambiguous. Understanding TEE's potential benefits and limitations in this population could significantly influence clinical practice. This review aims to scrutinize the current literature on the use of TEE before cardioversion in AF patients. The principal objective is to understand TEE's potential benefits and limitations comprehensively. The study seeks to offer a clear understanding and practical recommendations for clinical practice, thereby improving the management of AF patients before cardioversion using TEE. A literature search of databases was conducted using the keywords "Atrial Fibrillation," "Cardioversion" and "Transesophageal echocardiography," resulting in 640 articles. These were narrowed to 103 following title and abstract reviews. After applying exclusion and inclusion criteria with a quality assessment, 20 papers were included: seven retrospective studies, 12 prospective observational studies, and one randomized controlled trial (RCT). Stroke risk associated with direct-current cardioversion (DCC) potentially results from post-cardioversion atrial stunning. Thromboembolic events occur post cardioversion, with or without prior atrial thrombus or cardioversion complications. Generally, cardiac thrombus localizes in the left atrial appendage (LAA), a clear contraindication to cardioversion. Atrial sludge without LAA thrombus in TEE is a relative contraindication. TEE before electrical cardioversion (ECV) in anticoagulated AF individuals is uncommon. In AF patients planned for cardioversion, contrast enhancement facilitates thrombus exclusion in TEE images, reducing embolic events. Left atrial thrombus (LAT) frequently occurs in AF patients, necessitating TEE examination. Despite the increased use of pre-cardioversion TEE, thromboembolic events persist. Notably, patients with post-DCC thromboembolic events had no LA thrombus or LAA sludge. The use of TEE-guided DCC has grown due to its ability to detect atrial thrombi pre-cardioversion, aiding risk stratification. Thrombus in the left atrium also signals an elevated risk of future thromboembolic events in AF patients. While atrial stunning post cardioversion detected by TEE is a significant risk factor for future thromboembolic events, further evidence is required. Therapeutic anticoagulation is essential during and post cardioversion, even if no atrial thrombus is detected. Current data recommends cardioversion guided by TEE, particularly in outpatient settings.

Anteriolateral versus anterior-posterior electrodes in external cardioversion of atrial fibrillation: A systematic review and meta-analysis of clinical trials

The efficacy of anteriolateral versus anterior-posterior electrode positions in the success of atrial fibrillation's (AF) electrical cardioversion is unclear. Our aim is to perform a meta-analysis to compare the success rate of both electrode positions. PUBMED, WOS, OVID, and SCOPUS were searched. Inclusion criteria were clinical trials that compared anterior-lateral with anterior-posterior electrodes in external cardioversion of AF. After the full-text screening, 11 trials were included in the analysis. The total number of patients included in the study is 1845. The pooled analysis showed a statistically significant association between anterior-lateral electrode and increased cardioversion rate of AF (odds ratio [OR] = 1.40, 95% confidence interval [CI] = 1.02-1.92, p = .04). Subgroup analysis revealed a statistically significant association between the anterior-lateral electrode and increased cardioversion rate of AF in subgroups of less than five shocks, patients with 60 years old or more and patients with left atrial (LA) diameter >45 mm (OR = 1.72, 95% CI = 1.17-2.54, p = .006), (OR = 1.73, 95% CI = 1.18-2.54, p = .005), and (OR = 1.86, 95% CI = 1.04-3.34, p = .04), respectively. Anteriolateral electrode is more effective than anterior-posterior electrode in external cardioversion of AF, particularly in patients who have received less than 5 shocks, are 60 years old or older and have a LA diameter greater than 45 mm.

Giant Left Atrial Thrombus Despite Anticoagulation with Apixaban in a Patient with Mitral Stenosis and Atrial Fibrillation

Patient: Female, 64-year-old

Final Diagnosis: Thrombus

Symptoms: Fatigue • palpitation

Medication: —

Clinical Procedure: —

Specialty: Cardiology

A pilot image interpretation teaching intervention to improve competence and confidence of radiographers to detect left ventricular thrombus in routine cardiac MRI scans

INTRODUCTION

Prompt diagnosis of left ventricular (LV) thrombus is clinically important, as it may require immediate anti-coagulation treatment. The aim of this study was to determine if a teaching intervention delivered by cardiovascular magnetic resonance (CMR) physicians would increase the CMR radiographers' ability to detect LV thrombus on a routine CMR scan.

METHODS

A cohort of 25 patients (14 with and 11 without LV thrombus) were identified. A multi-parametric CMR protocol had been performed in all patients. Ten radiographers reviewed the 25 randomised anonymised studies on a workstation, documenting the presence/absence of LV thrombus and their confidence level on a 7-point Likert scale. Two senior CMR fellows then delivered a focused teaching programme to the radiographers and all 25 randomised scans were reassessed 1 month after the teaching intervention.

RESULTS

Following dedicated training, there was a significant improvement in correct thrombus identification per radiographer (pre-training: 75 ± 6% vs post-training: 85 ± 6%, p = 0.009). The size of the thrombus was not associated with the likelihood of incorrectly identifying LV thrombus size prior to the training session (p = 0.2), but a trend was observed between smaller thrombus size and incorrect identifications post-training (p = 0.06). The radiographers' overall confidence in assessing the cases prior to the teaching session was high (5.6 ± 0.8 out of 7). Following the teaching session, self-reported confidence did not vary significantly (5.9 ± 0.7 out of 7, p = 0.42). When evaluating the teaching session, radiographers provided very positive feedback, rating the usefulness of the teaching intervention as highly educative (8.8 ± 0.4 out of 10).

CONCLUSIONS

This is the first study that has explored the ability and confidence of CMR radiographers in detecting LV thrombus on routine CMR scans as a result of the teaching intervention delivered by CMR physicians.

IMPLICATIONS FOR PRACTICE

A teaching intervention can improve CMR radiographers' diagnostic skills and diagnostic confidence.

Determinants of left atrium thrombi in scheduled cardioversion: an ENSURE-AF study analysis

Aims

ENSURE-AF (NCT 02072434) was the largest prospective randomized clinical trial of anticoagulation for cardioversion in atrial fibrillation (AF), which also provides the largest prospective dataset for transoesophageal echocardiography (TOE) prior to cardioversion. This ancillary analysis investigated determinants of TOE-detected left atrium thrombi (LAT) in patients scheduled for electrical cardioversion (ECV).

Methods and results

The ENSURE-AF multicentre PROBE evaluation trial compared edoxaban 60 mg once daily (QD) with enoxaparin/warfarin in 2199 subjects undergoing ECV of non-valvular AF. Patients were stratified by the use of TOE, anticoagulant experience, and selected edoxaban dose. Electrical cardioversion was cancelled or deferred when TOEdetected LAT. In total, 1183 subjects were stratified to the TOE arm and LAT was reported in 91 (8.2%). In univariate analysis, age ≥75 years (26.4% vs. 16.9%, P = 0.0308), lower weight (86.5 ± 15.0 vs. 90.7 ± 18.0 kg, P = 0.0309), lower creatinine clearance (80.1 ± 30.6 vs. 93.2 ± 33.9 mL/min, P = 0.0007), heart failure (59.3% vs. 43.0%, P = 0.0029), and diuretic treatment (53.9% vs. 40.1%, P = 0.0141) were more prevalent in the LAT group. Non-significant trends were seen for higher mean CHA₂DS₂-VASc score (3.0 ± 1.41 vs. 2.7 ± 1.48, P = 0.0571) and more prevalent anticoagulation use prior to enrolment (60.4% vs. 50.3%, P = 0.0795) in the LAT group. In logistic regression analysis, age (P = 0.0202) and heart failure (P = 0.0064) were independently associated with LAT.

Conclusion

Elective ECV is commonly cancelled or deferred due to TOE-detected LAT in patients with non-valvular AF. Age ≥75 years and heart failure were associated with the presence of LAT.

One-stop hybrid procedure combining catheter ablation and left atrial appendage closure increases long-term risk for adverse events in patients with atrial fibrillation

INTRODUCTION

Combined catheter ablation (CA) and left atrial appendage closure (LAAC) have proven to be a feasible and safe strategy in treating patients with nonvalvular atrial fibrillation (AF). However, the interactions between CA and LAAC have not been systematically explored. We analyzed the impact of CA on long-term outcomes of LAAC in patients with AF treated with the hybrid procedure.

METHODS

A total of 107 consecutive patients with AF who underwent LAAC were divided into two groups: group A (n = 61) included patients who underwent CA followed by LAAC during the same procedure and group B (n = 46) included patients who underwent LAAC only. All patients underwent systematic transesophageal echocardiography (TEE) follow-up.

RESULTS

In group A, CA resulted in severe edema of the left atrial ridge (LAR), which manifested as an increase in LAR thickness from 4.6 ± 0.4 mm before CA to 6.8 ± 0.6 mm (P < .01) after CA. TEE at 45 days showed that the incidence of peri-device leakage was significantly higher in group A than in group B (45.9% vs 4.3%, P < .001). At the 12-month follow-up, the peri-device leakage rate remained higher in group A than in group B (14.8% vs 2.2%, P < .01). Three (4.9%) patients in group A experienced transient ischemia attacks; no events were reported in group B during the 1-year follow-up.

CONCLUSION

Edema of LAR with the single-stage procedure that consists of CA followed by LAAC could result in increased peri-device leakage and decreased compression rate over time, which may be also associated with elevated risk profiles when compared with an LAAC-only procedure.

Clinical Discussions in Antithrombotic Therapy Management : A Delphi Consensus Panel

For some years now, direct-acting oral anticoagulants (DOACs) have entered the clinical practice for stroke prevention in non-valvular atrial fibrillation (NVAF) or prevention and treatment of venous thromboembolism (VTE). However, there is uncertainty on DOAC use in some clinical scenarios not fully explored by clinical trials, but commonly encountered in the real world. We report a Delphi Consensus on DOAC use in NVAF and VTE patients. The consensus dealt with 16 main topics: (1) clinical superiority of DOACs compared to VKAs; (2) DOACs as a first-line treatment in patients with AF; (3) therapeutic options for patients undergoing electrical cardioversion; (4) selection of patients suitable for switching from VKAs to DOACs; (5) and (7) role of general practitioners in the follow-up of patients receiving a DOAC; (6) duties of Italian oral anticoagulation therapy centers; (8) role of therapy with DOACs in oncological patients with NVAF; (9) role of DOACs in oncological patients with VTE; (10) methods for administration and therapy compliance for DOACs; (11) drug interactions; (12) safety of low doses of DOACs; (13) therapeutic management of frail patients with NVAF; (14) therapeutic management of NVAF patients with glomerular filtration rate <30 ml/min (15); advantages of DOACs for the treatment of frail patients; (16) limitations on therapeutic use of DOACs. Sixty-two cardiologists from Italy expressed their level of agreement on each statement by using a 5-point Likert scale (1: strongly disagree, 2: disagree, 3: somewhat agree, 4: agree, 5: strongly agree). Namely, votes 1-2 were considered as disagreement while votes 3-5 as agreement. Agreement among the respondents of ≥66% for each statement was considered consensus. A brief discussion about the results for each topic is also reported.

Prevalence and clinical characteristics associated with left atrial thrombus detection: Apixaban

BACKGROUND

The prevalence of left atrial appendage (LAA) thrombus detection by transesophageal echocardiogram (TEE) in patients with non-valvular atrial fibrillation (AF) anticoagulated with apixaban is not well defined and identification of additional risk factors may help guide the selection process for pre-procedural TEE. The purpose of our study was to retrospectively analyze the prevalence of LAA thrombus detection by TEE in patients continuously anticoagulated with apixaban for ≥ 4 wk and evaluate for any cardiac risk factors or echocardiographic characteristics which may serve as predictors of thrombus formation.

AIM

To retrospectively analyze the prevalence of LAA thrombus detection by TEE in patients continuously anticoagulated with apixaban.

METHODS

Clinical and echocardiographic data for 820 consecutive patients with AF undergoing TEE at Augusta University Medical Center over a four-year period were retrospectively analyzed. All patients (apixaban: 226) with non-valvular AF and documented compliance with apixaban for ≥ 4 wk prior to index TEE were included.

RESULTS

Following ≥ 4 wk of continuous anticoagulation with apixaban, the prevalence of LAA thrombus and LAA thrombus/dense spontaneous echocardiographic contrast was 3.1% and 6.6%, respectively. Persistent AF, left ventricular ejection fraction < 30%, severe LA dilation, and reduced LAA velocity were associated with thrombus formation. Following multivariate logistic regression, persistent AF (OR: 7.427; 95%CI: 1.02 to 53.92; P = 0.0474), and reduced LAA velocity (OR: 1.086; 95%CI: 1.010 to 1.187; P = 0.0489) were identified as independent predictors of LAA thrombus. No Thrombi were detected in patients with a CHA₂DS₂-VASc score ≤ 1.

CONCLUSION

Among patients with non-valvular AF and ≥ 4 wk of anticoagulation with apixaban, the prevalence of LAA thrombus detected by TEE was 3.1%. This suggests that continuous therapy with apixaban does not completely eliminate the risk of LAA thrombus and that TEE prior to cardioversion or catheter ablation may be of benefit in patients with multiple risk factors.

Left atrial thrombus despite continuous direct oral anticoagulant or warfarin therapy in patients with atrial fibrillation: insights into rates and timing of thrombus resolution

PURPOSE

Left atrial thrombus (LAT) may be detected by transesophageal echocardiography (TEE) in patients with atrial fibrillation (AF) or flutter (AFL) despite continuous anticoagulation therapy. We sought to examine the rates and timing of LAT resolution in response to changes in anticoagulation regimen.

METHODS

A retrospective study of 1517 consecutive patients on ≥ 4 weeks continuous oral anticoagulation (OAC) undergoing TEE prior to either direct current cardioversion or catheter ablation for AF or AFL was performed. Patients who had LAT on index TEE imaging and had follow-up TEEs were analyzed.

RESULTS

Despite ≥ 4 weeks of continuous anticoagulation therapy, 63 (4.2%) patients had LAT. Forty-four patients (median age 67 [IQR 58, 74]; 33 [75%] male; 25 [57%] on direct oral anticoagulant [DOAC]) had follow-up TEEs performed. Upon detection of LAT on index TEE, 8 patients switched from warfarin to a DOAC, 21 patients switched from a DOAC to warfarin or another DOAC, and 15 patients remained on the same OAC. Over median 4.2 months (IQR 2.9, 6.6), LAT resolution was seen in 25 (57%) patients. Of the 25 patients who had LAT resolution, 7 (28%) required TEE imaging > 6 months after index TEE to show clearance of thrombus. Rates of LAT resolution were similar between patients who had alterations in OAC and those who did not (52 vs. 60%; P = 0.601).

CONCLUSIONS

After initial detection of left atrial thrombus despite uninterrupted anticoagulation for atrial fibrillation or flutter, > 40% patients have persistent clot despite additional extended anticoagulation.

Treatment of Acute Atrial Fibrillation: Ventricular Rate Control and Restoration of Sinus Rhythm

Atrial fibrillation (AF) is a familiar arrhythmia seen in the emergency department and the general population. In the past it was treated in the majority of cases by controlling the ventricular rate, whether the AF is acute or chronic. However, ventricular rate control alone does not address the underlying problem and the patients still remain in AF, cardiac output and symptoms have not been optimally corrected. There is definite risk of thromboembolism. Restoration of sinus rhythm is the only way of resuming the normal conduction physiology of the heart and correcting these problems This article provides a review of the two major principles of rhythm treatment of acute AF: rate control and restoration of sinus rhythm. Transthoracic electrical cardioversion is the mainstay of treatment in haemodynamically unstable AF, whereas in stable AF, there is a choice between rate control and restoration of sinus rhythm, or they can be carried out in conjunction with each other.

A novel method to estimate blood flow velocity in the left atrial appendage using enhanced computed tomography: role of Hounsfield unit density ratio at two distinct points within the left atrial appendage

Low blood flow velocity in the left atrial appendage (LAA) indicates a high risk of thromboembolism. Although transesophageal echocardiography (TEE) has been the standard method with which to evaluate the LAA blood flow velocity, a clinically noninvasive method is desired. We hypothesized that the ratio of the Hounsfield unit (HU) density at two distinct points within the LAA represents the blood flow velocity in the LAA. We retrospectively investigated 60 consecutive patients with atrial fibrillation (paroxysmal type, n = 29) who underwent enhanced computed tomography (CT) and TEE. The peak emptying flow velocity in the LAA (LAAPV) was evaluated using TEE. HU density was measured at proximal and distal sites of the LAA (LAAp and LAAd) on CT images. The LAAd/LAAp ratio was correlated with the LAAPV (P < 0.01, r = 0.69). Among several indices, the HU ratio was the most significant parameter associated with the LAAPV (β = 0.469, CI 28.602-68.286, P < 0.001). Receiver-operating characteristic analysis (area under the curve, 0.91) demonstrated that an HU density ratio cutoff of 0.32 discriminated a low LAAPV (<25 cm/s) with sensitivity of 90% and specificity of 84%. Flow velocity of the LAA can be estimated by the HU density ratio at distal and proximal sites within the LAA. Our method might be a feasible substitution for TEE to discriminate patients with a reduced LAAPV.

Advances in anticoagulation management of patients undergoing cardioversion of nonvalvular atrial fibrillation

Atrial fibrillation (AF) is a major cause of stroke. The restoration of sinus rhythm through cardioversion, either chemical or electrical is a common practice. Interestingly, there is an incremental increase from the baseline risk for embolisation in the immediate post-cardioversion period, with most events occurring within 10 days from cardioversion. Especially patients with recent onset AF show the lowest rates of antithrombotic therapy, while having a high stroke risk. Despite the increased risk for embolisation, anticoagulation in patients undergoing cardioversion of atrial fibrillation is often inadequate. Moreover, since the implementation of non-vitamin K antagonists oral anticoagulants (DOACs) there are several therapeutic approaches for pericardioversion anticoagulant therapy and not all suits to all patients. In addition, the extensive use of transesophageal echocardiography provides an alternative strategy, especially useful for patients of high haemorrhagic risk. In this review article, we aim to provide an update on the anticoagulation strategies for patients undergoing cardioversion of non-valvular atrial fibrillation in the advent of the use of DOACs.

Structural Comparison between the Right and Left Atrial Appendages Using Multidetector Computed Tomography

The three-dimensional (3D) structures of the right atrial appendage (RAA) and left atrial appendage (LAA) were compared to clarify why thrombus formation less frequently occurs in RAA than in LAA. Morphological differences between RAA and LAA of 34 formalin-preserved cadaver hearts were investigated. Molds of RAA and LAA specimens were made and the neck areas, volumes of the atrial appendages (AA), and amount of pectinate muscles (PMs) were analyzed using multidetector computed tomography. In RAA, most PMs were connected to one another and formed a “dendritic” appearance and the inner surface area was smaller than in LAA. RAA had smaller volumes and larger neck areas than LAA. The ratios of the neck area/volume were larger and the amounts of PMs were smaller in RAA than in LAA. The volumes, neck areas, and amount of PMs of RAA were significantly correlated with those of LAA. According to the 3D structure, RAA appears to be suited for a more favorable blood flow, which may explain why the thrombus formation is less common in RAA than in LAA. Examining not only LAA but also RAA by transesophageal echocardiography may be useful in high-risk patients of thrombus formation in LAA because the volume, neck area, and amount of PMs of LAA reflect the shape of RAA.

Effectiveness of Left Atrial Appendage Exclusion Procedures to Reduce the Risk of Stroke: A Systematic Review of the Evidence

Background—

Atrial fibrillation is an important cause of cardioembolic stroke. Oral anticoagulants (OAC) reduce stroke risk but increase the risk of serious bleeding. Left atrial appendage (LAA) procedures have been developed to isolate the LAA from circulating blood flow, as an alternative to OAC. We conducted a systematic review of the benefits and harms of surgical and percutaneous LAA exclusion procedures.

Methods and Results—

We searched multiple data sources, including Ovid MEDLINE, Cochrane, and Embase, through January 7, 2015. Of 2567 citations, 20 primary studies met prespecified inclusion criteria. We abstracted data on patient characteristics, stroke, mortality, and adverse effects. We assessed study quality and graded the strength of evidence using published criteria. Trials found low-strength evidence that percutaneous LAA exclusion confers similar risks of stroke and mortality as continued OAC, but this evidence was limited to the Watchman device in patients eligible for long-term OAC. Observational studies found moderate-strength evidence of serious harms with a variety of percutaneous LAA procedures. There is low-strength evidence that surgical LAA exclusion does not add significant harm during heart surgery for another indication, but evidence on stroke reduction is insufficient.

Conclusions—

There is limited evidence that the Watchman device may be noninferior to long-term OAC in selected patients. Data on effectiveness of LAA exclusion devices is lacking in patients ineligible for long-term OAC. Percutaneous LAA devices are associated with high rates of procedure-related harms. Although surgical LAA exclusion during heart surgery does not seem to add incremental harm, there is insufficient evidence of benefit.

Prevalence of Left Atrial Thrombus Detection by Transesophageal Echocardiography: A Comparison of Continuous Non-Vitamin K Antagonist Oral Anticoagulant Versus Warfarin Therapy in Patients Undergoing Catheter Ablation for Atrial Fibrillation

OBJECTIVES

The purpose of this study is to determine whether patients on ≥4 weeks of continuous non-vitamin K antagonist oral anticoagulant (NOAC) therapy require transesophageal echocardiography (TEE) before catheter ablation of atrial fibrillation (AF) or atrial flutter and to compare rates of left atrial (LA) thrombus and dense spontaneous echocardiographic contrast (SEC) in patients on NOAC versus warfarin therapy.

BACKGROUND

The impact of NOAC therapy on the rates of LA thrombus detection by TEE in patients undergoing catheter ablation of AF is unknown.

METHODS

Initial TEEs for 388 patients (median age, 65 years; 74% male) on ≥4 weeks of continuous NOAC (n = 183) or warfarin therapy (n = 205) undergoing catheter ablation of AF and flutter were reviewed.

RESULTS

After ≥4 weeks of therapy, the prevalence of LA thrombus and LA thrombus/dense SEC among patients on NOACs was 4.4% and 6.0%, respectively, which was comparable with that of patients on warfarin. LA thrombus rates among patients on dabigatran, rivaroxaban, and apixaban were 5.4%, 4.8%, and 0%, respectively (p = 0.46). Predictors of LA thrombus were congestive heart failure (odds ratio [OR]: 5.38; 95% confidence interval [CI]: 1.79 to 16.2; p = 0.003); and persistent AF (OR: 3.27; 95% CI: 1.06 to 10.2; p = 0.040).

CONCLUSIONS

Despite ≥4 weeks of anticoagulation, the rate of LA thrombus in patients on NOACs before catheter ablation of AF or atrial flutter was 4.4%. This suggests that continuous NOAC therapy does not eliminate the need for TEE before catheter ablation of AF.

Assessment of left and right atrial 3D hemodynamics in patients with atrial fibrillation: a 4D flow MRI study

Atrial fibrillation (AF) is associated with embolic stroke due to thrombus formation in the left atrium (LA). Based on the relationship of atrial stasis to thromboembolism and the marked disparity in pulmonary versus systemic thromboembolism in AF, we tested the hypothesis that flow velocity distributions in the left (LA) versus right atrium (RA) in patients with would demonstrate increased stasis. Whole heart 4D flow MRI was performed in 62 AF patients (n = 33 in sinus rhythm during imaging, n = 29 with persistent AF) and 8 controls for the assessment of in vivo atrial 3D blood flow. 3D segmentation of the LA and RA geometry and normalized velocity histograms assessed atrial velocity distribution and stasis (% of atrial velocities <0.2 m/s). Atrial hemodynamics were similar for RA and LA and significantly correlated (mean velocity: r = 0.64; stasis: r = 0.55, p < 0.001). RA and LA mean and median velocities were lower in AF patients by 15-33 % and stasis was elevated by 11-19 % compared to controls. There was high inter-individual variability in LA/RA mean velocity ratio (range 0.5-1.8) and LA/RA stasis ratio (range 0.7-1.7). Patients with a history of AF and in sinus rhythm showed most pronounced differences in atrial flow (reduced mean velocities, higher stasis in the LA). While there is no systematic difference in LA versus RA flow velocity profiles, high variability was noted. Further delineation of patient specific factors and/or regional atrial effects on the LA and RA flow velocity profiles, as well as other factors such as differences in procoagulant factors, may explain the more prevalent systemic versus pulmonary thromboembolism in patients with AF.

Prevalence of left atrial thrombus in patients with non-valvular atrial fibrillation. A systematic review and meta-analysis of the literature

We performed a meta-analysis about the prevalence of left atrial thrombus (LAT) in patients with atrial fibrillation (AF) undergoing trans-esophageal echocardiography (TEE). Studies reporting on LAT presence in AF patients were systematically searched in the PubMed, Web of Science, Scopus and EMBASE databases and the pooled LAT prevalence was evaluated as weighted mean prevalence (WMP). Seventy-two studies (20,516 AF patients) showed a LAT WMP of 9.8 % (95 %CI: 7.6 %-12.5 %). LAT presence was associated with a higher age (mean difference: 2.56, 95 %CI: 1.49-3.62), and higher prevalence of female gender (OR: 1.35, 95 %CI: 1.04-1.75), hypertension (OR: 1.78, 95 %CI: 1.38-2.30), diabetes mellitus (OR: 1.86, 95 %CI: 1.33-2.59) and chronic heart failure (OR: 3.67, 95 %CI: 2.40-5.60). Overall, LAT patients exhibited a higher CHADS2-score (mean difference 0.88, 95 %CI: 0.68-1.07) and a higher risk of stroke/systemic embolism (OR: 3.53, 95 %CI: 2.24-5.56) compared with those without LAT. A meta-regression showed an inverse association between LAT prevalence and the presence of anticoagulation (Z-value: -7.3, p< 0.001). Indeed, studies in which 100 % of patients received oral anticoagulation reported a 3.4 % WMP of LAT (95 %CI: 1.3 %-8.7 %), whereas studies in which 0 % of patients received anticoagulation showed a LAT WMP of 7.4 % (95 %CI: 2.3 %-21.5 %). Our data suggest that LAT is present in ≍10 % of AF patients, and is associated with a 3.5-fold increased risk of stroke/systemic embolism. Interestingly, LAT is also reported in some of patients receiving anticoagulation. The implementation of the screening of LAT in AF patients before cardioversion/ablation could be useful for the prevention of vascular events.

Left atrial appendage occlusion for stroke prevention

Atrial fibrillation (AF) remains the most common arrhythmia encountered in clinical practice. One of its more common deleterious effects is the development of thromboembolism leading to stroke. The left atrial appendage (LAA) has been shown to the site of the majority of thrombus formation leading to stroke. Anticoagulation with warfarin has been the treatment of choice for prevention of embolic events. Newer anticoagulants have been developed but they still have the potential side effect of causing major bleeding. Occlusion of the LAA has emerged as an alternative therapeutic approach to medical therapy. The aim of this article is to discuss in detail the role of the LAA in thromboembolism in AF, role of device and surgical therapies, and the current clinical data supporting their use. This is particularly timely in that there is now an approved LAA closure device approved in the US for stroke prevention in patients with nonvalvular AF.

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

The left atrial appendage (LAA) is a finger-like extension originating from the main body of the left atrium. Atrial fibrillation (AF) is the most common clinically important cardiac arrhythmia, occurring in approximately 0.4% to 1% of the general population and increasing with age to >8% in those >80 years of age. In the presence of AF thrombus, formation often occurs within the LAA because of reduced contractility and stasis; thus, attention should be given to the LAA when evaluating and assessing patients with AF to determine the risk for cardioembolic complications. It is clinically important to understand LAA anatomy and function. It is also critical to choose the optimal imaging techniques to identify or exclude LAA thrombi in the setting of AF, before cardioversion, and with current and emerging transcatheter therapies, which include mitral balloon valvuloplasty, pulmonary vein isolation, MitraClip (Abbott Laboratories, Abbott Park, Illinois) valve repair, and the implantation of LAA occlusion and exclusion devices. In this review, we present the current data regarding LAA anatomy, LAA function, and LAA imaging using the currently available noninvasive imaging modalities.

Cardiac Plug I and Amulet Devices: Left Atrial Appendage Closure for Stroke Prophylaxis in Atrial Fibrillation

Percutaneous left atrial appendage (LAA) occlusion has emerged as an exciting and effective modality for stroke prophylaxis in patients with non-valvular atrial fibrillation who are deemed too high risk for anticoagulation with warfarin or newer anticoagulants. The Amplatzer devices have been used in LAA occlusion for more than a decade, starting with off label use of an atrial septal occluder device for LAA occlusion. This was followed by introduction of a dedicated Amplatzer cardiac plug (ACP) 1 for LAA occlusion, and more recently, the second generation Amulet device, with reported better stability enhancing features, has been introduced. Both these devices are widely used outside the United States, however in the US only the WATCHMAN device has been FDA approved. Unlike the WATCHMAN device, where the evidence is continuously building as the data from two pivotal randomized controlled trials are emerging, most of the evidence for ACP devices is from pooled multicenter registry data. In this article, we review the device design, implantation techniques and the most recently published evidence for both the Amplatzer cardiac plug 1 and the newer Amulet device. Our goal is to summarize the most recent literature and discuss the current role of the Amplatzer devices in the exciting and rapidly growing field of percutaneous LAA occlusion.

Increased prothrombotic profile in the left atrial appendage of atrial fibrillation patients

BACKGROUND

Atrial fibrillation (AF) is associated with an increased risk for thromboembolic events. While observational data demonstrated that the majority of clots are formed within the left atrial appendage, the mechanisms behind this finding remain unclear also due to the fact that vitro studies so far have been hampered by the inability to isolate and culture cells from the atrial appendages.

METHODS

Patients suffering from AF undergoing cardiac surgery were recruited for this study and endocardial cells from their left (LAA) and right atrial appendage (RAA) were isolated and cultured according to a novel established protocol. Once in culture, cells were stimulated with TNF-α (10 ng/mL) and the expression of prothrombotic as well as proinflammatory markers was analyzed.

RESULTS

FACS analysis confirmed a high purity (98%) of isolated LAA endocardial cells. TNF-α significantly increased tissue factor (TF) and PAI-1 expression (n=5; P<0.005), while TFPI remained unchanged. Similarly, expression of VCAM-1 was significantly higher in the LAA as compared to the RAA (n=5; P<0.0001).

CONCLUSION

According to our newly established cell isolation protocol, this study reveals that in patients with AF, the endocardium of the LAA displays an increased prothrombotic and proinflammatory profile as compared to the RAA. This novel observation may constitute an important mechanism to explain the increased propensity of the LAA for clot formation, as well as the predominance of LAA-related thromboembolic complications in AF patients, and may have important implications for the development of novel treatment strategies.

Management of Atrial Fibrillation

Atrial fibrillation remains the most prevalent cardiac arrhythmia, and its incidence is increasing as the population ages. Common conditions associated with an increased incidence include advanced age, hypertension, heart failure, and valvular heart disease. Patients with atrial fibrillation may complain of palpitations, fatigue, and decreased exercise tolerance or may be completely asymptomatic. Options for treating patients who experience atrial fibrillation include rate-controlling drugs such as digoxin, β-blockers, and calcium channel blockers or a rhythm-controlling strategy with agents such as sodium channel blockers and potassium channel blockers. Atrial fibrillation increases the risk of stroke due to atrial thrombus formation and embolization. Anticoagulation with the vitamin K antagonist, warfarin, remains the most widely prescribed treatment option to decrease stroke risk. Several other antithrombotic agents have recently become available and offer excellent alternatives to warfarin. Catheter ablation can be undertaken as a nonpharmacologic rhythm control option with varying degrees of success depending on duration of atrial fibrillation and follow-up time from the procedure. This review article further describes the management options for patients presenting with atrial fibrillation.

Left ventricular thrombus development during ventricular fibrillation and resolution during resuscitation in a swine model of sudden cardiac arrest

BACKGROUND

Intracardiac thrombus is a well-known complication of low-flow cardiac states including acute myocardial infarction and atrial fibrillation. Little is known, however, about the formation of intracardiac (left ventricular [LV]) thrombus during the extreme low-flow state of cardiac arrest.

OBJECTIVE

Using a swine model of sudden cardiac arrest, we examined the sonographic development of LV thrombus over time after induction of ventricular fibrillation (VF) and resolution of thrombus with cardiopulmonary resuscitation (CPR).

METHODS

This observational study was IACUC approved. Forty-five Yorkshire swine were sedated, intubated, and instrumented under general anesthesia before VF was electrically induced. Sonographic data was collected immediately after VF induction and at 2-min intervals thereafter. Following 12min of untreated VF, resuscitation was initiated with closed chest compressions using an oxygen-powered mechanical resuscitation device. Observations were continued during attempted resuscitation. At the end of the experiment, the animals were euthanized while still at a surgical depth of anesthesia. The data was analyzed descriptively.

RESULTS

Sonographic evidence of LV thrombus was observed in 43/45 animals (95.6% [95%CI: 85.2%, 98.8%]). Thrombus was detected within 6min in 39/45 (86.7% [95%CI: 73.8%, 93.8%]) animals that developed thrombus. Thrombus resolved within 2min after initiation of chest compressions in 31/43 (72.1% [95%CI: 57.3%, 83.3%]) animals.

CONCLUSION

Similar to other low-flow cardiac states, LV thrombus develops early in the natural history of VF arrest and resolves quickly once forward flow is re-established by chest compressions. Institutional protocol number: 154600-8.

Atrial fibrillation

Atrial fibrillation is the most common arrhythmia affecting patients today. Disease prevalence is increasing at an alarming rate worldwide, and is associated with often catastrophic and costly consequences, including heart failure, syncope, dementia, and stroke. Therapies including anticoagulants, anti-arrhythmic medications, devices, and non-pharmacologic procedures in the last 30 years have improved patients' functionality with the disease. Nonetheless, it remains imperative that further research into AF epidemiology, genetics, detection, and treatments continues to push forward rapidly as the worldwide population ages dramatically over the next 20 years.

Contrast enhanced transesophageal echocardiography in patients with atrial fibrillation referred to electrical cardioversion improves atrial thrombus detection and may reduce associated thromboembolic events

Aims

Transesophageal echocardiography (TEE) is the gold standard for the detection of thrombi in patients with atrial fibrillation (AF) before undergoing early electrical cardioversion (CV). However, TEE generates inconclusive results in a considerable number of patients. This study investigated the influence of contrast enhancement on interpretability of TEE for the detection of left atrial (LA) thrombi compared to conventional TEE and assessed, whether there are differences in the rate of thromboembolic events after electrical cardioversion.

Methods

Of 180 patients with AF (51 females, 65.2±13 years) who were referred to CV, 90 were examined with native imaging and contrast enhancement within the same examination (group 1), and 90 were examined with native TEE alone and served as control (group 2). Cineloops of the multiplane examination of the LA and LA appendage (LAA) were stored digitally before and, in group 1, after intravenous bolus application of a transpulmonary contrast agent. Images of group 1 were assessed offline and the diagnosis of LA thrombi was made semi-quantitatively: 1= thrombus present; 2=inconclusive result; 3=no thrombus. The presence of spontaneous echocontrast (SEC) was registered and flow velocity in the LA appendage (LAA-flow) was measured. All patients in whom CV was performed were followed up for 1 year or until relapse of AF. CV related adverse events were defined as any thromboembolic event within 1 week after CV.

Results

No serious adverse events occurred during TEE and contrast enhanced imaging. In group 1 atrial thrombi were diagnosed in 14 (15.6%) during native and in 10 (11.1%) patients during contrast enhanced imaging (p<0.001). Of the 10 patients with thrombi in the contrast TEE group, 7 revealed a decreased LAA-flow (≤0,3m/s) and 8 showed moderate or marked SEC. Uncertain results were significantly more common during native imaging than with contrast enhanced TEE (16 vs. 5 patients, p<0.01). Thrombi could definitely be excluded in 60 (66.7%) during conventional and in 75 patients (83.3%) during contrast enhanced TEE (p<0.01). CV was performed subsequently after exclusion of thrombi and at the discretion of the investigator. In group 1, 74 patients (82.2%) were cardioverted and no patient suffered a CV related complication (p=0.084). In group 2, 76 patients (84.4%) underwent CV, of whom 3 suffered a thromboembolic complication after CV (2 strokes, 1 peripheral embolism).

Conclusion

In patients with AF planned for CV contrast enhancement renders TEE images more interpretable, facilitates the exclusion of atrial thrombi and may reduce the rate of embolic adverse events.

Correlation of right atrial appendage velocity with left atrial appendage velocity and brain natriuretic Peptide

Background

Left atrial appendage (LAA) anatomy and function have been well characterized both in healthy and diseased people, whereas relatively little attention has been focused on the right atrial appendage (RAA). We sought to evaluate RAA flow velocity and to compare these parameters with LAA indices and with a study of biomarkers, such as brain natriuretic peptide, among patients with sinus rhythm (SR) and atrial fibrillation (AF).

Methods

In a series of 79 consecutive patients referred for transesophageal echocardiography, 43 patients (23 with AF and 20 controls) were evaluated.

Results

AF was associated with a decrease in flow velocity for both LAA and RAA [LAA velocity-SR vs. AF: 61 ± 22 vs. 29 ± 18 m/sec (p < 0.01), RAA velocity-SR vs. AF: 46 ± 20 vs. 19 ± 8 m/sec (p < 0.01)]. Based on simple linear regression analysis, LAA velocity and RAA velocity were positively correlated, and RAA velocity was inversely correlated with brain natriuretic peptide (BNP).

Conclusion

AF was associated with decreased RAA and LAA flow velocities. RAA velocity was found to be positively correlated with LAA velocity and negatively correlated with BNP. The plasma BNP concentration may serve as a determinant of LAA and RAA functions.