Findings of transoesophageal echocardiogram in appropriately anticoagulated patients with persistent atrial fibrillation prior to planned cardioversion

Effectiveness of Transesophageal Echocardiography in Preventing Thromboembolic Complications Before Cardioversion: A Narrative Review

Atrial fibrillation (AFib) is one of the most prevalent irregular heartbeats that doctors encounter. Clinicians typically pursue two main approaches for treatment, namely, controlling the heart rate and managing the heart rhythm. Under the rhythm control approach, AFib is addressed through cardioversion, which is achieved either with medications termed pharmacological cardioversion (PCV) or via an electrical shock termed electric cardioversion (ECV). While ECV proves instrumental in AFib management, it carries its own risk factors, potentially leading to blood clot-related complications such as embolic strokes. To counteract this potential downside, a well-established strategy involves the utilization of transesophageal echocardiography (TEE) to identify possible embolic sources before initiating cardioversion. The goal of this systematic review is to highlight the role of TEE in preempting embolic occurrences following ECV during the management of AFib. After conducting a thorough search of databases, namely, PubMed, PubMed Central, and Medline, a total of 36 studies were selected for this review article. Following a comprehensive evaluation of these studies, it was concluded that TEE plays a pivotal role in preventing thromboembolic complications during ECV for AFib. However, it is important to note that further research is needed to delve deeper into this matter. While existing evidence underscores its efficacy, additional investigation is needed to address this subject matter comprehensively.

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.

Is transesophageal echocardiography necessary before electrical cardioversion in patients treated with non-vitamin K antagonist oral anticoagulants? Current evidence and practical approach

According to current guidelines, non-vitamin K antagonist oral anticoagulants (NOACs) should be used at least 3 weeks before planned electrical cardioversion. In accordance with international atrial fibrillation (AF) guidelines, transesophageal echocardiography (TEE) is a pre-procedural examination recommended as an alternative to adequate oral anticoagulation. The strategy related to qualifying patients treated with NOACs for pre-procedural TEE differs in individual centers. Therefore, it is necessary to create an algorithm that will standardize estimation of left atrial appendage thrombus (LAAT) prevalence risk and thereby qualify NOAC-treated patients to TEE in the most effective way. We assessed the available studies on LAAT predictors. Risk factors for LAAT formation are not necessarily the same as the risk factors for thromboembolic events in patients with AF. The main risk factor for LAAT are as follows: previous intracardiac thrombus, irregular use of NOAC, inappropriate dose reduction of NOAC, previous stroke, CHA2DS2-VASc score ≥ 3 points, glomerular filtration rate < 60 mL/min/1.73 m², reduced left ventricular ejection fraction, or left atrial enlargement. Based on available evidence, we proposed algorithm guarantees more systematic approach to performing TEE in patients undergoing electrical cardioversion.

Prevalence of Left Atrial Thrombus in Anticoagulated Patients With Atrial Fibrillation

BACKGROUND

The prevalence of left atrial (LA) thrombus in patients with atrial fibrillation (AF) or atrial flutter (AFL) on guideline-directed anticoagulation is not well known, yet this may inform transesophageal echocardiogram (TEE) use before cardioversion or catheter ablation.

OBJECTIVES

The purpose of this study was to quantify LA thrombus prevalence among patients with AF/AFL on guideline-directed anticoagulation and to identify high-risk subgroups.

METHODS

EMBASE, MEDLINE, and CENTRAL were systematically searched from inception to July 2020 for studies reporting on LA thrombus prevalence among patients with AF/AFL undergoing TEE following at least 3 weeks of continuous therapeutic oral anticoagulation with vitamin K antagonists (VKAs) or direct oral anticoagulants (DOACs). Meta-analysis was performed using random effects models.

RESULTS

Thirty-five studies describing 14,653 patients were identified. The mean-weighted LA thrombus prevalence was 2.73% (95% confidence interval [CI]: 1.95% to 3.80%). LA thrombus prevalence was similar for VKA- and DOAC-treated patients (2.80%; 95% CI: 1.86% to 4.21% vs. 3.12%; 95% CI: 1.92% to 5.03%; p = 0.674). Patients with nonparoxysmal AF/AFL had a 4-fold higher LA thrombus prevalence compared with paroxysmal patients (4.81%; 95% CI: 3.35% to 6.86% vs. 1.03%; 95% CI: 0.52% to 2.03%; p < 0.001). LA thrombus prevalence was higher among patients undergoing cardioversion versus ablation (5.55%; 95% CI: 3.15% to 9.58% vs. 1.65%; 95% CI: 1.07% to 2.53%; p < 0.001). Patients with CHA₂DS₂-VASc scores ≥3 had a higher LA thrombus prevalence compared with patients with scores ≤2 (6.31%; 95% CI: 3.72% to 10.49% vs. 1.06%; 95% CI: 0.45% to 2.49%; p < 0.001).

CONCLUSIONS

LA thrombus prevalence is high in subgroups of anticoagulated patients with AF/AFL, who may benefit from routine pre-procedural TEE use before cardioversion or catheter ablation.

Prevalence of left atrial thrombus by real time three-dimensional echocardiography in patients undergoing electrical cardioversion of atrial fibrillation: A contemporary cohort study

BACKGROUND

The prevalence of left atrial thrombi in patients scheduled for electrical cardioversion (ECV) of atrial fibrillation (AF) remains unknown in contemporary real-life practice.

METHODS AND RESULTS

Patients scheduled for ECV underwent transesophageal echocardiography (TEE) regardless of AF duration and type of anticoagulant. Of 277 consecutive patients (65% men, mean age 71 ± 10 years, CHA₂ DS₂ -VASc 3.1 ± 1.4), 92 were on direct oral anticoagulants (DOACs) and 99 on antivitamin K (AVK) oral agents for at least 3 weeks before and 4 after ECV. Eighty-five patients with paroxysmal AF on low-molecular-weight heparin were also considered. Real time three-dimensional TEE detected left atrial appendage (LAA) thrombus in 7% of patients, without significant difference among three groups (P = .334). Anticoagulation was ineffective in eight patients on AVK oral agents, two of them had thrombus. Eight patients assumed incorrectly DOACs, four of them had thrombus. Among the 175 patients on effective anticoagulation, five showed thrombus, three on AVK oral agents, and two on DOACs (P = .716). Effective anticoagulation was associated with reduced risk of thrombosis (OR: 0.16, 95%CI: 0.06-0.45, P = .001). In patients with correct anticoagulation, predictors of thrombus were CHA₂ DS₂ VASc (for each point of increment OR: 1.97, 95%CI: 1.08-3.61, P = .029), low left ventricular ejection fraction (OR: 0.92, 95%CI: 0.86-0.99, P = .026), and degree of spontaneous echo-contrast (for each point increase OR: 10, 95%CI: 2-39, P < .0001).

CONCLUSION

Patients with AF, on effective anticoagulation, had a prevalence of thrombus not negligible regardless of type of anticoagulant. TEE is prudent before ECV and mandatory if unsuccessful anticoagulation is proved or suspected.

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.

Left Atrial Appendage Thrombus Formation Despite Continuous Non-Vitamin K Antagonist Oral Anticoagulant Therapy in Atrial Fibrillation Patients Undergoing Electrical Cardioversion or Catheter Ablation: A Comparison of Dabigatran and Rivaroxaban

Left atrial appendage thrombus (LAAT) may be detected by transesophageal echocardiography (TOE) in patients with atrial fibrillation (AF) despite continuous anticoagulation therapy. We examined the factors predisposing to LAAT in patients treated with the anticoagulants dabigatran and rivaroxaban. We retrospectively evaluated 1,256 AF patients from three centres who underwent TOE before electrical cardioversion (n = 611, 51.4%) or catheter ablation (n = 645, 48.6%) from January 2013 to December 2019 and had been on at least three weeks of continuous dabigatran (n = 603, 48%) or rivaroxaban (n = 653, 52%) therapy. Preprocedural TOE diagnosed LAAT in 51 patients (4.1%), including 30 patients (5%) treated with dabigatran and 21 patients (3.2%) treated with rivaroxaban (p=0.1145). In multivariate logistic regression, predictors of LAAT in patients treated with dabigatran were non-paroxysmal AF (vs. paroxysmal AF) (OR = 6.2, p=0.015), heart failure (OR = 3.22, p=0.003), and a eGFR <60 ml/min/1.73 m² (OR = 2.65, p=0.012); the predictors in patients treated with rivaroxaban were non-paroxysmal AF (vs. paroxysmal AF) (OR = 5.73, p=0.0221) and heart failure (OR = 3.19, p=0.116). In ROC analysis of the dabigatran group, the area under the curve (AUC) for the CHA₂DS₂-VASc-RAF score was significantly higher (0.78) than those for the CHADS₂, CHA₂DS₂-VASc, and R₂CHADS₂ scores (0.67, 0.70, and 0.72, respectively). In the rivaroxaban group, the CHA₂DS₂-VASc-RAF score also performed significantly better (AUC of 0.77) than the CHADS₂, CHA₂DS₂-VASc, and R₂CHADS₂ scores (AUC of 0.66, 0.64, and 0.67, respectively). The risk of LAAT was the same for patients in both treatment groups. In all patients, non-paroxysmal AF or heart failure, and in patients treated with dabigatran an eGFR <60 ml/min/1.73 m², were independent predictors of LAAT. The new CHA₂DS₂-VASc-RAF scale had the highest predictive value for LAAT in the entire study population.

Thrombus in the left atrial appendage in patients with atrial fibrillation treated with non-vitamin K antagonist oral anticoagulants in clinical practice-A multicenter registry

BACKGROUND

The prevalence and predictors of left atrial appendage thrombus (LAAT) in patients with non-valvular atrial fibrillation (AF) who have been treated with non-vitamin K antagonist oral anticoagulants (NOACs) are not well defined. We aimed to assess the occurrence and predictors of LAAT on transesophageal echocardiography (TOE) in patients with non-valvular AF treated with NOACs for at least 3 weeks.

METHODS

Consecutive patients with non-valvular AF who underwent TOE before catheter ablation or electrical cardioversion in three high-reference centers between 2014 and 2018 were included. Patients on apixaban were excluded from the study due to low numbers in this category. All patients received NOACs for at least 3 weeks before TOE.

RESULTS

A total of 1148 patients (female, 38.1%; mean age, 62.1 years) referred to our centers for catheter ablation of AF (52.1%) or electrical cardioversion (47.9%) were included. Patients were on rivaroxaban (51.9%) or dabigatran (48.1%). Preprocedural TOE revealed LAAT in 4.4% of all patients. Multivariable logistic regression analysis showed the CHA2DS2-VASc score ≥2 points (OR = 2.11; 95% CI, 1.15-3.88; P = .0161), non-paroxysmal AF (OR = 6.30; 95% CI, 2.22-17.91; P = .0005), and GFR <60 mL/min/1.73 m² (OR = 2.05; 95% CI, 1.14-3.67; P = .0160) were independent predictors of LAAT in patients treated with NOACs.

CONCLUSIONS

In non-valvular AF patients treated with NOACs, the prevalence of LAAT was 4.4% before electrical cardioversion or ablation. In addition to the CHA2DS2-VASc score, the type of AF and renal function should be considered in the stratification of thromboembolism risk in AF patients and qualification for a preprocedural TOE.

Comparison of transesophageal echocardiography findings after different anticoagulation strategies in patients with atrial fibrillation: a systematic review and meta-analysis

Background

High risk of embolic events exists in both patients with chronic atrial fibrillation (AF) and patients in the perioperative period of ablation (effective treatment for AF). Therefore, anticoagulant therapy is important. Oral anticoagulants can be divided into two major categories: vitamin K antagonists (VKAs) and non-vitamin K antagonist oral anticoagulants (NOACs). VKAs, represented by warfarin, have been widely used as traditional anticoagulants, whereas NOACs have been used in clinical practice, but their anticoagulant effects and side effects are still the focus of research. We used a meta-analysis to compare the incidence of left atrial thrombi (LAT) between different anticoagulants.

Methods

We searched PubMed, EMBASE, Web of Science, and the Cochrane Library databases for observational studies that compared the transesophageal echocardiography (TEE) findings for patients treated with NOACs and VKAs. The incidence of LAT and dense spontaneous echocardiographic contrast (dense SEC) were extracted as the basis of the meta-analysis.

Results

Fifteen studies were included in the meta-analysis. We found that patients anticoagulated with NOACs and VKAs had similar incidence of LAT (OR = 0.74, 95%CI: 0.55–1.00). After excluding the heterogeneous article by sensitivity analysis, we found the incidence of LAT in patients anticoagulated with NOACs is lower than VKAs (OR = 0.59, 95%CI: 0.42–0.84). The results of subgroup analysis showed that the incidence of LAT among three types of NOACs have no significant difference (dabigatran vs. rivaroxaban, OR = 1.16 [0.75, 1.81]; rivaroxaban vs. apixaban, OR = 0.97 [0.54, 1.74]; dabigatran vs. apixaban, OR = 1.09 [0.55, 2.16]).

Conclusion

Patients anticoagulated with NOACs may have lower incidence of LAT than VKAs. The incidence of LAT among different type of NOACs are similar.