Novel Models for the Prediction of Left Atrial Appendage Thrombus in Patients with Chronic Nonvalvular Atrial Fibrillation

Predictors of left atrial appendage thrombus in atrial fibrillation patients undergoing cardioversion

BACKGROUND

Atrial fibrillation and atrial flutter represent the most prevalent clinically significant cardiac arrhythmias. While the CHA2DS2-VASc score is commonly used to inform anticoagulation therapy decisions for patients with these conditions, its predictive power is limited. Therefore, we sought to improve risk prediction for left atrial appendage thrombus (LAAT), a known risk factor for stroke in these patients.

METHODS

We developed and validated an explainable machine learning model using the eXtreme Gradient Boosting algorithm with 5 × 5 nested cross-validation. The primary outcome was to predict the probability of LAAT in patients with atrial fibrillation and atrial flutter who underwent transesophageal echocardiogram prior to cardioversion. Our algorithm used 37 demographic, comorbid, and transthoracic echocardiographic variables.

RESULTS

A total of 795 patients were included in our analysis. LAAT was present in 11.3% of the patients. The average age of patients was 63.3 years and 34.7% were women. Patients with LAAT had significantly lower left ventricular ejection fraction (29.9% vs 43.5%; p < 0.001), lower E' lateral velocity (5.7 cm vs. 7.9 cm; p < 0.001) and higher E/A ratio (2.6 vs 1.8; p = 0.002). Our machine learning model achieved a high AUC of 0.79, with a high specificity of 0.82, and modest sensitivity of 0.57. Left ventricular ejection fraction was the most important variable in predicting LAAT. Patients were split into 10 buckets based on the percentile of their predicted probability of having thrombus. The lower the percentile (e.g., 10%), the lower the probability of having thrombus. Using a cutoff point of 0.16 which includes 10.0% of the patients, we can rule out thrombus with 100% confidence.

CONCLUSION

Using machine learning, we refined the predictive power of predicting LAAT and explained the model. These results show promise in providing better guidance for anticoagulation therapy and cardioversion in AF and AFL patients.

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.

Echocardiographic predictors of thrombus in left atrial appendage—The role of novel transthoracic parameters

Introduction

The left atrium appendage thrombus (LAAT) formation is a complex process. A CHA2DS2-VASc scale is an established tool for determining the thromboembolic risk and initiation of anticoagulation treatment in patients with atrial fibrillation or flutter (AF/AFL). We aimed to identify whether any transthoracic echocardiography (TTE) parameters could have an additional impact on LAAT detection.

Methods

That is a sub-study of multicenter, prospective, observational study LATTEE (NCT03591627), which enrolled 3,109 consecutive patients with AF/AFL referred for transesophageal echocardiography (TEE) before cardioversion or ablation.

Results

LAAT was diagnosed in 8.0% of patients. The univariate logistic regression analysis [based on pre-specified in the receiver operating characteristic (ROC) analysis cut-off values with AUC ≥ 0.7] identified left ventricular ejection fraction (LVEF) ≤ 48% and novel TTE parameters i.e., the ratios of LVEF and left atrial diameter (LAD) ≤ 1.1 (AUC 0.75; OR 5.64; 95% CI 4.03–7.9; p &lt; 0.001), LVEF to left atrial area (LAA) ≤ 1.7 (AUC 0.75; OR 5.64; 95% CI 4.02–7.9; p &lt; 0.001), and LVEF to indexed left atrial volume (LAVI) ≤ 1.1 (AUC 0.75, OR 6.77; 95% CI 4.25–10.8; p &lt; 0.001) as significant predictors of LAAT. In a multivariate logistic regression analysis, LVEF/LAVI and LVEF/LAA maintained statistical significance. Calculating the accuracy of the abovementioned ratios according to the CHA2DS2-VASc scale values revealed their highest predictive power for LAAT in a setting with low thromboembolic risk.

Conclusion

Novel TTE indices could help identify patients with increased probability of the LAAT, with particular applicability for patients at low thromboembolic risk.

Incidence of left atrial appendage thrombus despite 3 weeks of anticoagulation and the need for precardioversion echocardiography

Background

One of the most catastrophic complications of Atrial fibrillation (AF) is thromboembolic stroke. Current guidelines recommend that 3 weeks of anticoagulation is adequate prior to direct current cardioversion (DCCV) to prevent thromboembolism. Here we present data regarding, which anticoagulant is most likely to show a presence of an Left atrial appendage thrombus (LAAT) on trans esophageal echocardiogram (TEE) for DCCV despite 3 weeks of anticoagulation.

Objective

To investigate the effectiveness of both vitamin k antagonist (VKA) and direct oral anticoagulants (DOAC) in patients with AF as an anticoagulant for LAAT after 3 weeks of medication.

Methods

This is a single‐high volume tertiary center, where TEE precardioversion is the standard practice. We reviewed data over 10 months where DCCV was intended on individuals with AF who were fully anticoagulated for at least 3 weeks with either a VKA or taking a DOAC.

Results

The data showed a statistical difference between patients who were fully anticoagulated for at least 3 weeks with VKA in comparison to DOACs. Patients on DOACs are significantly less likely to have an LAAT after at least 3 weeks of anticoagulation. OR = 0.04 (CI 95% 0.005–0.42; p‐value < .05). Despite anticoagulation for at least 3 weeks, 40% of our patients still had a LAAT.

Conclusion

Our data indicates that all patients should be required to undergo a TEE prior to DCCV. This data also adds to the current evidence and supports the use of DOAC in AF to prevent LAAT.

Proposal for a clinical and an echocardiographic score for prediction of left atrial thrombosis in atrial fibrillation patients undergoing early electrical cardioversion

AIMS

Left atrial thrombosis (LAT) is usually detected by transesophageal echocardiography (TEE). The aim of the present study was to identify clinical and echocardiographic factors associated with left atrial thrombosis in atrial fibrillation (AF) patients undergoing early electrical cardioversion (ECV) in order to create scores that can predict LAT, in a non-invasive way.

METHODS

A consecutive cohort of patients with persistent AF scheduled for ECV was evaluated by transthoracic echocardiography and TEE. By a logistic regression model, variables significantly associated with LAT were assessed and introduced in predictive models to develop both a clinical and an echocardiographic prediction score for the presence of LAT.

RESULTS

In total, 125 patients [median 71 (range 49-88) years, 60.0% males] were enrolled. Transesophageal echocardiography showed LAT in 35 patients (28%). The clinical variables significantly associated with LAT were previous stroke (OR = 4.17), higher CHA₂ DS₂ -VASc score (OR = 1.93), lower estimated glomerular filtration rate (OR = 0.80), and higher brain natriuretic peptide levels (OR = 1.44). Among echocardiographic parameters, E/e' ratio was directly associated with LAT (OR = 2.25), while an inverse correlation was detected with left ventricular ejection fraction (OR = 0.43) and total global left atrial strain (OR = 0.59). Two prediction scores (clinical and echocardiographic) were developed. The positive predictive values of the clinical and the echocardiographic score were 80% and 100%, respectively, while the negative predictive values were 98% and 94%, respectively. Combined use of the scores reached a positive and negative predictive value of 100%.

CONCLUSIONS

When providing concordant information the two scores are able to correctly identify patients with or without LAT. An external validation is necessary to demonstrate their usefulness in the clinical practice.

CHA2DS2-VASc Score as a Predictor for Left Atrial Thrombus or Spontaneous Echo Contrast in Patients with Nonvalvular Atrial Fibrillation: A Meta-Analysis

Objective

This meta-analysis aimed at exploring the predictive value of CHA₂DS₂-VASc score for the left atrial thrombus (LAT) or left atrial spontaneous echo contrast (LASEC) in patients with nonvalvular atrial fibrillation (NVAF).

Methods

PubMed, Embase, Web of Science, ScienceDirect, Cochrane Library, and Chinese core journals of the CNKI and Wanfang databases were searched to identify all the relevant papers that were published up to January 2020. The data were extracted for pooled odds ratios (ORs) with 95% confidence intervals (CIs), heterogeneity, subgroup, publication bias, and sensitivity analysis.

Results

Overall, 15 studies containing 6223 patients with NVAF were enrolled. All studies were evaluated for LAT, and 12 studies were evaluated for LASEC. The pooled analysis using a random-effects model showed that a high CHA₂DS₂-VASc score was related with LAT/LASEC (pooled OR = 1.59, 95% CI: 1.35–1.88, P < 0.001) with high heterogeneity (I² = 76.9%, P < 0.001) and LAT (pooled OR = 1.83, 95% CI: 1.44–2.33, P < 0.001) with high heterogeneity (I² = 79.4%, P < 0.001). The subgroup analysis demonstrated that the sample size may be the main source of heterogeneity. Although the Begg's funnel plot based on 15 studies for LAT/LASEC (P = 0.029) and 12 studies for LAT (P = 0.046) indicated the presence of publication bias among the included studies, the trim-and-fill method verified the stability of the pooled outcomes. In addition, sensitivity analysis indicated that all effects were stable.

Conclusion

The results of this meta-analysis showed that the CHA₂DS₂-VASc score is related with LAT and LASEC in patients with NVAF. However, more studies are warranted to address this issue.

Association of left atrial deformation indices with left atrial appendage thrombus in patients with non valvular atrial fibrillation

Aim

Assessment of the value of left atrial deformation indices for prediction of left atrial appendage functioning patients with non-valvular atrial fibrillation.

Method

The study included 250 patients with non-valvular atrial fibrillation and normal left atrial dimension. Trans-thoracic and trans-esophageal echocardiography were performed. Patients were divided into two groups; patients with LAA thrombus (group I) and patients without LAA thrombus (group II), a correlation between trans-esophageal and trans-thoracic data was analyzed.

Results

Group I included110 patients (44%) and Group II 140 patients (56%). By TDI mean LA strain and strain rate were lower in group I (21.89 ± 7.75% vs 35.14 ± 9.28%; p < 0.001) and (1.15/sec, IQR 0.12–3/sec versus 2.1/sec, IQR 0.21–3/sec, p < 0.001) respectively. By speckle tracking PALS and strain rate were lower in group I (24.79 ± 7.78% vs 37.63 ± 8.64%; p value < 0.001) and (0.95 ± 0.32/sec. Vs 1.27 ± 0.32/sec p, value < 0.001) respectively. By TEE; group I had lower LAA EF (39.2 ± 13.55% vs 53.86 ± 12.7%); p < 0.001, and lower LAA emptying velocity (17.53 cm/s, IQR 9.54–77.4 vs 63.5 cm/s, IQR 7.89–86.4; p < 0.001). There was a good correlation between LA TDI and speckle tracking PALS and PALSR and LAA EF% and velocity p < 0.001. TDI and PALS and PALSR were found to be significant predictors for LAA thrombus (P < 0.05) with good sensitivity and specificity.

Conclusion

Left atrium deformation indices are predictors of LAA thrombus or SEC in patients with non-valvular AF with accepted sensitivity and specificity.

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.