Left Atrial Appendage Thrombus Prior to Atrial Fibrillation Ablation in the Era of Direct Oral Anticoagulants

External validation of CLOTS-AF score in patients with atrial fibrillation undergoing transesophageal echocardiography

BACKGROUND

Predicting thromboembolic events caused by left atrial appendage thrombosis (LAAT) is crucial since it is the most concerning complication of nonvalvular atrial fibrillation (NVAF).

OBJECTIVE

The objective of this study was to establish the predictive effectiveness of a novel scoring system known as the CLOTS-AF score in identifying the existence of thrombus using transesophageal echocardiography (TEE) in patients with NVAF and to compare it with the CHA2DS2-VASc score.

METHODS

This study was conducted retrospectively with 668 NVAF patients who underwent TEE in a single centre. The patients were categorized into two categories based on the presence or absence of LAAT on TEE. The CLOTS-AF score was computed for all patients, which was then compared to the CHA2DS2-VASc score.

RESULTS

Thrombus was detected in the left atrial appendage (LAA) of 114 (17%) individuals. The study revealed that the thrombus (+) group had substantially higher CHA2DS2-VASc scores and CLOTS-AF scores (3 (2-4); 4 (3-6), p < .001), respectively. Furthermore, the CLOTS-AF score was shown to be a better predictor of LAAT than the CHA2DS2-VASc score (AUC: 0.70 vs. AUC: 0.61, p < .001).

CONCLUSIONS

This study could validate the CLOTS-AF score in an external cohort by demonstrating its significant predictive power and underscoring its vital role in clinical practice.

Does Spontaneous Echo Contrast in the Left Atrial Appendage Increase Thromboembolism Risk After Left Atrial Appendage Closure? A Retrospective Study on Its Impact on Device-Related Thrombosis and Arterial Thromboembolic Events

Background: Left atrial appendage closure (LAAC) prevents arterial thromboembolic events (ATEs) in nonvalvular atrial fibrillation (AF). Spontaneous echo contrast (SEC) is an independent risk factor for left atrial appendage (LAA) thrombosis; however, there is little knowledge about the relationship between preoperative SEC and the increased risk of device-related thrombosis (DRT) or ATEs in patients with AF who have undergone LAAC. Methods: This retrospective study focused on patients with nonvalvular AF who successfully underwent LAAC surgery. Transesophageal echocardiography (TEE) was used to assess preoperative LAA status. SEC in LAA Grades 0-2 was defined as LAASEC-, and Grades 3-4 or previously diagnosed LAA thrombus formation as LAASEC+. Results: A total of 519 AF patients (432 in LAASEC- group and 87 in LAASEC+ group) who underwent LAAC were included. At the 1-year follow-up, there was no significant difference in the incidence of DRT (2.5 vs. 3.8%, p = 0.636), ATEs (0.5 vs. 0%, p = 0.525), and all-cause mortality (2.1% vs. 2.3%, p = 0.899) between the LAASEC- group and the LAASEC+ group. However, the LAASEC+ group had higher proportions of cauliflower-type LAA and ≥ 3 lobes. Conclusions: The difference in preoperative LAA thrombosis or LAASEC was not related to the incidence of DRT or ATEs in AF patients within 1 year after LAAC.

Efficacy and Safety of New Oral Anticoagulants versus Warfarin in the Resolution of Atrial Fibrillation with Left Atrial/Left Atrial Appendage Thrombus: A Systematic Review and Meta-Analysis

Background

To compare the efficacy and safety of novel oral anticoagulants (NOACs) and vitamin K antagonists (VKAs) in nonvalvular atrial fibrillation (NVAF) patients with left atrial/left atrial thrombosis through a systematic review and meta-analysis.

Methods

The CBM (China Biology Medicine disc), CNKI (China National Knowledge Infrastructure), VIP (Chinese Technology Periodical Database), Wanfang, PubMed, Embase, Cochrane Library, and Web of Science databases were searched for relevant studies from their inception to June 30, 2022.

Results

Twelve articles (eight cohort studies and four randomized controlled trials) involving 982 patients were included. Meta-analysis showed that NOACs had a significantly higher thrombolysis rate than VKAs (78.0% vs. 63.5%, odds ratio (OR) = 2.32, 95% confidence interval (CI) 1.71 to 3.15, p < 0.0001). Subgroup analysis revealed rivaroxaban to be more effective than VKAs, whereas there was no significant difference between dabigatran and apixaban. There were no significant differences in embolic events, bleeding, or all-cause mortality. Thrombus resolution analysis showed higher left ventricular end-diastolic diameter and smaller left atrial diameter in the effective group than in the ineffective group.

Conclusions

NOACs are more effective in thrombolysis than VKAs in NVAF patients with left atrial thrombosis, and there is no increased risk of adverse events compared with VKAs.

Omitting transesophageal echocardiography before catheter ablation of atrial fibrillation

BACKGROUND

Data about necessity of performing transesophageal echocardiography (TOE) prior to every catheter ablation (CA) of atrial fibrillation (AF) is scarce. We aimed to evaluate the safety of an individualized risk-based approach to TOE with respect to thromboembolic cerebrovascular events (CVE) in patients undergoing CA for AF or left atrial tachycardia (AT).

METHODS

We performed a retrospective clinical study based on our institutional registry database. Patients undergoing CA for AF or left-sided AT following initial AF ablation at two participating centers were enrolled. Prior to the procedure, patients were scheduled for TOE only if they had a history of thromboembolic stroke, left atrial appendage (LAA) thrombus, or inappropriate anticoagulation regimen in the previous 3 to 4 weeks. The incidence of periprocedural cerebrovascular thromboembolic events was assessed.

RESULTS

We analyzed 1155 patients (median age 70 years, 54.8% male, 48.1% had persistent AF/AT). In 261 patients, a TOE was performed; in 2 patients (0.7%), an LAA thrombus was detected, which led to cancellation of the catheter ablation; in 894 patients, the TOE was omitted. Of the 1153 (0.35%) patients who underwent ablation, 4 (0.35%) experienced a CVE (one TIA and three strokes). The rate of CVE in our study does not exceed that reported in most multicenter trials. The low event rates limited statistical analysis of possible risk factors for CVE. In all 4 patients with CVE, post-CVE imaging showed the absence of LAA thrombus.

CONCLUSIONS

An individualized selective approach to TOE before catheter ablation of AF or left AT showed a very low risk of overt intraprocedural thromboembolic events for the population in our study. A further randomized controlled study is needed to determine whether TOE prior to catheter ablation without ICE could be omitted in patients with uninterrupted OAC without previous thromboembolic events or a history of left atrial thrombus.

Transesophageal echocardiography and computerized tomography angiography mismatch in left atrial appendage thrombus evaluation

BACKGROUND

Transesophageal echocardiography (TEE) is the gold standard test for the diagnosis of left atrial appendage (LAA) thrombus. Nonetheless, computerized tomography angiography (CTA) is readily used to exclude LAA thrombus before pulmonary vein isolation (PVI) and LAA closure procedures. We aimed to assess the comparability of LAA thrombus diagnosis using chest CTA scans in patients with atrial fibrillation who underwent TEE.

METHODS

Retrospective collection of consecutive patients with atrial fibrillation who underwent TEE and chest CTA within 30 days and had evidence of spontaneous echo contrast (SEC) or LAA thrombus on TEE. Clinical, demographic, and echo data were collected. Prospective analysis of the CTA for evidence of LAA thrombus in the same group of patients was performed. We compared the findings of the two modalities.

RESULTS

Out of 1550 patients with atrial fibrillation who underwent TEE examinations in the study period, 63 patients underwent TEE within 30 days of a chest CTA scan. Twenty-three patients had LAA thrombus and 40 had some degree of SEC according to TEE. On CTA, 11 were interpreted as positive with a high level of suspicion for the presence of an LAA thrombus. Six patients (26.1%) had LAA thrombus according to both CT and TEE. Therefore, low concordance was found between test results (chi-squared continuity correction = 5.5, df  = 1, and P -value = 0.01902).

CONCLUSION

The discrepancy between CTA and TEE results suggests these examinations might be more suitable as complementary examinations to exclude LAA thrombus.

Treatment of Persistent Left Atrial Appendage Thrombus in Patients with Atrial Fibrillation on Adequate Oral Anticoagulation: Pathways of Care for All-comers and Heart Failure Patients

In patients with AF, the presence of left atrial/left atrial appendage (LA/LAA) thrombus is related to an increased risk of thromboembolic events. Anticoagulation therapy, either with vitamin K antagonists or novel oral anticoagulants (NOACs) is therefore mandatory in AF with LA/LAA thrombus in order to lower the risk of stroke or other systemic embolic events. Despite the efficacy of these treatments, some patients will have persistent LAA thrombus remaining or may have contraindications to oral anticoagulation. Currently, little is known about the occurrence, risk factors and resolution rate of LA/LAA thrombus in patients who are already under optimal chronic oral anticoagulation, including vitamin K antagonists or NOACs. The common action in clinical practice in this scenario is switching from one to another anticoagulant drug exhibiting a different mechanism of action. Repeated cardiac imaging is then advised within several weeks to visually verify thrombus dissolution. Finally, there is a substantial scarcity of data on the role and optimal use of NOACs after LAA occlusion. The aim of this review is to critically evaluate data and provide up-to-date information on the best antithrombotic strategies in this challenging clinical scenario.

Characteristics, Thrombus Resolution, and Long-Term Outcomes in Patients with Nonvalvular Atrial Fibrillation and Atrial Thrombus

To assess the prevalence and management of atrial thrombus in patients with nonvalvular atrial fibrillation (NVAF) and identify the risk factors of the nonresolution of atrial thrombus. This single-center retrospective observational study consecutively enrolled patients with NVAF and atrial thrombus detected using transesophageal echocardiography (TEE) or cardiac computed tomography angiography (CTA) from January 2012 to December 2020. Patients with prior left atrial appendage (LAA) intervention were excluded. The primary endpoint was the presence of atrial thrombus, while the secondary endpoint was the complete resolution of atrial thrombus. The prevalence of atrial thrombus in patients with NVAF was 1.4%. Ninety patients with atrial thrombus (mean age 62.8 ± 11.9 years and 61.1% men) were finally analyzed. Atrial thrombus was in the LAA in 82 (91.1%) patients. During follow up, 60% of the patients showed complete resolution of atrial thrombus. Congestive heart failure (odds ratio [OR]: 8.94; 95% confidence interval [CI]: 1.67-47.80) and a history of ischemic stroke (OR: 8.28; 95% CI: 1.48-46.42) were independently associated with the risk of the nonresolution of atrial thrombus. The presence of atrial thrombus in patients with NVAF who received anticoagulation therapy is non-negligible. Even in anticoagulated patients, TEE or cardiac CTA might still be needed. Congestive heart failure and a history of ischemic stroke are risk factors of the nonresolution of atrial thrombus.

Effectiveness and Safety of DOACs in Atrial Fibrillation Patients Undergoing Catheter Ablation: Results from the China Atrial Fibrillation (China-AF) Registry

BACKGROUND

Direct oral anticoagulants (DOACs) have increasingly become an alternative to warfarin in atrial fibrillation (AF) patients. Nonetheless, data on the effectiveness and safety of DOACs in periprocedural of catheter ablation (CA) in real-world practice was relatively rare.

METHODS AND RESULTS

3385 AF patients underwent initial CA and never used oral anticoagulant before enrollment between April 2013 and December 2018 were involved from China Atrial Fibrillation (China-AF) Registry. Warfarin, rivaroxaban and dabigatran were used in 1896 (56.0%), 718 (21.2%), and 771 (22.8%) patients, respectively. Propensity score matching was used to balance covariates across study groups. No significant differences were observed in rivaroxaban-warfarin, dabigatran-warfarin and dabigatran-rivaroxaban cohort for thromboembolic (TE) and major bleeding (MB) incidence. Similar results were also revealed in low-dose rivaroxaban (R_LD)-warfarin, low-dose dabigatran (D_LD)-warfarin and D_LD-R_LD cohort. However, the risk of non-MB was higher not only on standard-dose of rivaroxaban but also on R_LD when compared with warfarin and with D_LD, respectively.

CONCLUSIONS

In this study, the incidence of TE and MB were both comparable in standard- or low-dose DOACs versus warfarin and between the two DOACs, whereas the risk of non-MB was higher in rivaroxaban than in warfarin and in R_LD than in D_LD.

Characteristics of non-valvular atrial fibrillation with left atrial appendage thrombus who are undergoing appropriate oral anticoagulation therapy

We investigated the characteristics of patients with non-valvular atrial fibrillation (NVAF) and left atrial (LA) appendage (LAA) thrombus who had been given appropriate oral anticoagulation therapy. We studied 737 NVAF patients who were scheduled for catheter ablation or electrical cardioversion. All patients received appropriate oral anticoagulation therapy for at least 3 weeks prior to echocardiography in accordance with the guidelines. Whether LAA thrombus was present or absent on transesophageal echocardiography (TEE) was determined by at least three senior echocardiologists. LAA thrombi were observed in 22 patients (3.0%). Multivariate logistic regression analysis showed that LAA flow and LA volume index were both independent predictors of LAA thrombus formation; however, LAA flow (≤ 18 cm/s) was indicated as a more powerful predictor. Moreover, the prevalence of LAA thrombus formation in patients with NVAF without LA enlargement (LA volume index ≤ 34 mL/m2) was extremely rare (0.4%). LAA thrombus formation in patients with a mildly dilated LA volume index of 34-49.9 mL/m2 and paroxysmal AF was also extremely rare (0.0%). LAA flow is strongly associated with LAA thrombus formation, even in NVAF patients treated with appropriate oral anticoagulation therapy. Augmented oral anticoagulation therapy or transcatheter or surgical LAA closure should be considered for such patients, especially for those with an LAA flow < 18 cm/s. Furthermore, TEE for evaluating LAA thrombus before catheter ablation or electrical cardioversion may be unnecessary for NVAF patients who are undergoing appropriate oral anticoagulation therapy, depending on LA size.

A Comparative Study of Three Imaging Modalities for Size Selection of a Watchman Left Atrial Appendage Closure Device

PURPOSE

To compare the results of computed tomography angiography (CTA), transesophageal echocardiography (TEE), and digital subtraction angiography (DSA) measurements and analyze their accuracy, correlation, and consistency in patients who have successfully undergone left atrial appendage closure (LAAC).

MATERIALS AND METHODS

A total of 157 non-valvular atrial fibrillation (AF) patients who underwent LAAC with Watchman devices were included in the study. The maximum diameter and depth of LAA were recorded using CTA, TEE, and DSA. Correlations and agreements were compared.

RESULTS

The LAAC procedure was performed successfully in all patients using the Watchman device. There was no significant difference between DSA and TEE measurements of the diameter of the LAA ostium. LAA ostium diameter obtained by CTA, however, was greater than that from DSA and TEE. Correlations were good between LAA ostium diameter measured by TEE, CTA, and DSA and Watchman device size. DSA measurements and actual device size showed the widest limits of agreement, followed by TEE; CTA measurements showed the narrowest limits of agreement. For LAA depth measurements, mean CTA measurements were higher than those of TEE and DSA. There was no significant difference in depth measurements among the three imaging modalities.

CONCLUSION

CTA, TEE, and DSA measurements exhibited good correlations with Watchman device size. The ostium diameter and depth of the LAA measured by CTA were greater than those measured by TEE and DSA. The relevance and concordance of CTA measurements were the strongest.

Left Atrial Dysfunction, Fibrosis and the Risk of Thromboembolism in Patients With Paroxysmal and Persistent Atrial Fibrillation

Background and Objectives

Left atrial (LA) fibrosis is an important component of the arrhythmogenic substrate and is related to LA dysfunction in patients with atrial fibrillation (AF). However, its relationship with functional changes and the risk of thrombus in patients with paroxysmal AF (PAF) and persistent AF (PeAF) remains unclear.

Methods

We included 139 patients with preprocedural cardiac magnetic resonance imaging (CMR) and transesophageal echocardiography (TEE) for the first AF catheter ablation. Spontaneous echo contrast (SEC) and multiple parameters of LA were measured from TEE and CMR. LA fibrosis was evaluated by late gadolinium enhancement of LA (LA-LGE) of CMR.

Results

The presence of SEC was higher in patients with PeAF than in patients with PAF (26.4% vs. 11.9%, p=0.03). The patients with SEC had more enlarged LA size and impaired function of LA and LAA, regardless of AF type. However, the area of LA-LGE was more extensive in patients with SEC in PeAF (27.5±15.9 vs. 20.1±10.3, p=0.033), not in PAF. In PAF, maximal LA volume index was closely related to the presence of SEC with marginal trend toward significance (odd ratio [OR], 1.07; 95% confidence interval [CI], 0.99–1.16; p=0.072). Whereas, a larger area of LA-LGE and lower emptying flux of LA appendage were independently related with SEC (OR, 1.10; 95% CI, 1.0–1.20; p=0.049 and OR, 0.93; 95% CI, 0.86–0.99; p=0.022, respectively) after adjusting related cardiovascular risk factors of SEC

Conclusions

In this study, we suggest that the risk of thrombus is provoked by LA enlargement with dysfunction in early-stage AF and by stiffened LA with fibrosis rather than LA size when it becomes PeAF.

Prevalence and predictors of left atrial thrombosis in atrial fibrillation patients treated with non-vitamin K antagonist oral anticoagulants

BACKGROUND

Few data are available regarding the prevalence of left atrium (LA) thrombi in atrial fibrillation (AF) patients treated with non-vitamin K antagonist oral anticoagulants (NOACs). Methods: We evaluated the prevalence and predictors of LA/LA appendage (LAA) thrombi in non-valvular AF patients treated with NOACs referring to a single centre for a scheduled electrical cardioversion (ECV) or catheter ablation (CA). Transesophageal echocardiography (TEE) was performed within 12 h prior to the index procedure.

RESULTS

A total of 352 consecutive patients with non-valvular AF treated with NOACs were included in this analysis (ECV group n = 176 and CA group n = 176) between 2013 and 2018. 85 patients (24.2%) were on dabigatran, 150 (42.7%) on rivaroxaban, 104 (29.6%) on apixaban and 13 (3.7%) on edoxaban. A LA/LAA thrombus was detected by TEE in 27 (7.7%) patients, 18 in the ECV group and nine in the ablation group; 18 (5.1%) patients presented dense LA/LAA spontaneous echo contrast (SEC). Predictors of LA/LAA thrombi were a CHA₂DS₂-VASc score > 3 (OR 4.54, 95% CI 1.50 - 13.70, p value = .007) and obesity (OR 6.01, 95% CI 1.95 - 18.50, p value = .001).

CONCLUSIONS

Among real-world patients with non-valvular AF treated with NOACs, we found a high incidence of LA/LAA thrombi compared to previous reports. The main predictors of LA/LAA thrombosis were a CHA₂DS₂-VASc score > 3 and obesity.

Efficiency of the Left Atrial Appendage Thrombus Dissolution in Patients with Persistent Nonvalvular Atrial Fibrillation with Warfarin or Direct Oral Anticoagulants Therapy

Aim. Compare the incidence of the left atrial appendage (LAA) thrombus dissolution in patients with persistent nonvalvular atrial fibrillation receiving warfarin and direct oral anticoagulants (DOAC).

Materials and methods. 68 patients with persistent nonvalvular atrial fibrillation were included in a retrospective study (age was 59.7±9.8 years, 60.3% men), in whom at least one repeated transesophageal echocardiographic examination was performed after detecting a thrombus. After detecting a thrombus in the LAA, 37 (54.4%) patients started or continued taking warfarin in doses that ensure the INR maintenance at the level of 2-3, 14 (20.6%) started or continued taking dabigatran at a dose of 150 mg 2 times/day, 14 (20.6%) started or continued taking rivaroxaban 20 mg 1 time/day and 3 (4.4%) started or continued taking apixaban 5 mg 2 times/day. Repeated transesophageal echocardiographic examination was performed on average 33.3±14.2 days after the first one.

Results. Dissolution of a previously identified thrombus was found in 26 (83.9%) of 31 patients receiving DOAC and in 19 (51.4%) of 37 patients receiving warfarin (p=0.011). The logistic regression analysis showed that the chances of a thrombus dissolution in LAA while taking DOAC are 14.8 times (95% confidence interval [CI] was 2.469-88.72) higher than while taking warfarin. The size and the rate at which blood is expelled from the LAA also have an independent influence on the chances of thrombus dissolution. An increase in the size of a thrombus by 1 mm reduces the chances of a thrombus dissolution by 1.136 (95% CI was 1.040-1.244) times, and an increase in the rate of blood expulsion from the LAA by 1 cm/sec increases these chances by 1.105 (95% CI was 1.003-1.219) times.

Conclusion. In the present study, the incidence of the LAA thrombus dissolution in patients with persistent nonvalvular atrial fibrillation while receiving DOAC was higher than while receiving warfarin.

Prevalence of Left Atrial Appendage Thrombus in Patients Anticoagulated With Direct Oral Anticoagulants: Systematic Review and Meta-analysis

BACKGROUND

Multiple studies have examined the prevalence of left atrial appendage thrombus (LAAT) in patients anticoagulated with direct oral anticoagulants (DOACs) and have reported conflicting results.

METHODS

Studies reporting the prevalence of LAAT on transesophageal echocardiography (TEE) after 3 or more weeks of DOAC therapy were identified. The proportions of anticoagulated patients diagnosed with LAAT were pooled using random-effects models. Prespecified subgroup analyses by the indication of TEE (pre-atrial fibrillation [AF] ablation vs cardioversion) and TEE strategy (routine use vs selective) were conducted via stratification.

RESULTS

Forty studies were identified: 22 full manuscripts and 18 abstracts. Only 11 studies performed TEE routinely. Most studies included patients with paroxysmal AF and low thromboembolic risk. The pooled prevalence of LAAT was 2.5% (95% confidence interval [1.6%-3.4%]). The prevalence of LAAT is lower in the pre-AF ablation group compared with pre-cardioversion (1.1% vs 4.0%, P = 0.033). Routine TEE strategy yielded a lower LAAT prevalence in both groups (0.1% vs 2.3%, P = 0.002 and 3.2% vs 5.8%, P = 0.432, respectively).

CONCLUSION

The reported prevalence of LAAT on TEE in patients treated with DOACs is highly variable. Factors associated with a high LAAT prevalence were pre-cardioversion indication and selective TEE strategy. Routine use of TEE before AF ablation may not be warranted.

Comparison of effectiveness and safety between uninterrupted direct oral anticoagulants with and without switching to dabigatran in atrial fibrillation ablation

Introduction

Recent studies have demonstrated the feasibility of uninterrupted direct oral anticoagulants (DOACs) with a temporary switch to dabigatran (“dabigatran bridge”) for atrial fibrillation (AF) ablation. We compared the effectiveness and safety between uninterrupted DOACs with and without the “dabigatran bridge” in patients taking factor Xa inhibitors.

Methods

AF patients on factor Xa inhibitors (rivaroxaban/apixaban/edoxaban) undergoing catheter ablation were eligible (n = 348). Brain MRI was performed within 2 days after the procedure to detect silent cerebral events (SCEs). Rivaroxaban/apixaban/edoxaban were uninterruptedly used in 153 patients (Group 1); these DOACs were switched to dabigatran on the day of AF ablation in 195 patients (Group 2). After propensity score matching, the unfractionated heparin (UFH) amount and the activated clotting time (ACT) kinetics during the procedure, the SCE incidence, and the follow‐up complications (30 days, thromboembolism and major/minor bleeding) in the two groups were compared.

Results

Group 2 had higher initial ACT value and shorter time to optimal ACT (>300 seconds) than Group 1 (184 ± 36 s vs 145 ± 22 s, and 34 ± 29 s vs 43 ± 34 s, P < .05, respectively). Group 2 tended to require less amount of UFH to achieve optimal ACT than Group 1, but the total amount of UFH for the procedure was comparable. Group 2 had lower SCE incidence than Group 1 (16.2% vs 26.4%, P < .05). The prevalence of follow‐up complications was unchanged between the two groups.

Conclusions

Switching to dabigatran on the day of AF ablation decreases preclinical thromboembolic events with similar bleeding risk to uninterrupted factor Xa inhibitors.