Left Atrial Thrombus in Patients With Non-valvular Atrial Fibrillation: A Cross-Sectional Study in China

Development and validation of an interpretable machine learning model for predicting left atrial thrombus or spontaneous echo contrast in non-valvular atrial fibrillation patients

PURPOSE

Left atrial thrombus or spontaneous echo contrast (LAT/SEC) are widely recognized as significant contributors to cardiogenic embolism in non-valvular atrial fibrillation (NVAF). This study aimed to construct and validate an interpretable predictive model of LAT/SEC risk in NVAF patients using machine learning (ML) methods.

METHODS

Electronic medical records (EMR) data of consecutive NVAF patients scheduled for catheter ablation at the First Hospital of Jilin University from October 1, 2022, to February 1, 2024, were analyzed. A retrospective study of 1,222 NVAF patients was conducted. Nine ML algorithms combined with demographic, clinical, and laboratory data were applied to develop prediction models for LAT/SEC in NVAF patients. Feature selection was performed using the least absolute shrinkage and selection operator (LASSO) and multivariate logistic regression. Multiple ML classification models were integrated to identify the optimal model, and Shapley Additive exPlanations (SHAP) interpretation was utilized for personalized risk assessment. Diagnostic performances of the optimal model and the CHA2DS2-VASc scoring system for predicting LAT/SEC risk in NVAF were compared.

RESULTS

Among 1,078 patients included, the incidence of LAT/SEC was 10.02%. Six independent predictors, including age, non-paroxysmal AF, diabetes, ischemic stroke or thromboembolism (IS/TE), hyperuricemia, and left atrial diameter (LAD), were identified as the most valuable features. The logistic classification model exhibited the best performance with an area under the receiver operating characteristic curve (AUC) of 0.850, accuracy of 0.812, sensitivity of 0.818, and specificity of 0.780 in the test set. SHAP analysis revealed the contribution of explanatory variables to the model and their relationship with LAT/SEC occurrence. The logistic regression model significantly outperformed the CHA2DS2-VASc scoring system, with AUCs of 0.831 and 0.650, respectively (Z = 7.175, P < 0.001).

CONCLUSIONS

ML proves to be a reliable tool for predicting LAT/SEC risk in NVAF patients. The constructed logistic regression model, along with SHAP interpretation, may serve as a clinically useful tool for identifying high-risk NVAF patients. This enables targeted diagnostic evaluations and the development of personalized treatment strategies based on the findings.

Prevalence and predictors of left atrial thrombus in patients with rheumatic atrial fibrillation undergoing cardiac surgery: a cross-sectional study

BACKGROUND

Unlike non-rheumatic atrial fibrillation (AF), where left atrial thrombus (LAT) is predominantly confined to the left atrial appendage (LAA), a significant proportion of LAT in rheumatic AF occurs within the left atrial cavity (LAC). However, LAC thrombosis in rheumatic AF has not been extensively studied. This study aimed to evaluate the prevalence of LAT and its subtypes and identify potential predictors of LAT.

METHODS

This retrospective study included adult patients with rheumatic AF who underwent open-heart surgery for mitral valvular abnormalities between January 2019 and December 2020. LAT was identified through intraoperative inspection and categorized as either LAC thrombus or LAA thrombus. The prevalence of LAT and its subtypes was calculated, and logistic regression analysis was performed to identify predictors of LAT.

RESULTS

A total of 530 patients (mean age: 59.7 ± 9.5 years; male: 29.8%) with a predominance of mitral stenosis (59.6%) were included. LAT was identified in 82 patients (15.5%), including 44 (8.3%) with LAA thrombus and 38 (7.2%) with LAC thrombus. In the multivariable logistic regression model, coronary artery disease (OR: 6.35, 95% CI: 2.79-14.46, p < 0.001), larger left atrial diameter (OR: 1.31 per 10 mm increase, 95% CI: 1.02-1.68, p = 0.03), and moderate-to-severe mitral stenosis (OR: 1.77, 95% CI: 1.00-3.13, p = 0.05) were independently associated with an increased risk of LAT, whereas moderate-to-severe mitral regurgitation was independently associated with a decreased risk of LAT (OR: 0.21, 95% CI: 0.11-0.43, p < 0.001).

CONCLUSION

In patients with rheumatic AF undergoing open-heart mitral valve surgery, LAT can be located in either the LAA or LAC. The presence of LAT was independently associated with coronary artery disease, left atrial enlargement, and mitral valvular abnormalities. Timely screening and management of LAT are crucial to mitigate potentially fatal thromboembolic events.

Morphology and location of thrombus and sludge in patients with non-valvular atrial fibrillation

BACKGROUND

Stroke and thromboembolism in nonvalvular atrial fibrillation (NVAF) primarily arise from thrombi or sludge in the left atrial appendage (LAA). Comprehensive insight into the characteristics of these formations is essential for effective risk assessment and management.

METHODS

We conducted a single-center retrospective observational of 176 consecutive NVAF patients with confirmed atrial/appendage thrombus or sludge determined by a pre-ablation transesophageal echocardiogram (TEE) from December 2017 to April 2019. We obtained clinical and echocardiographic characteristics, including left atrial appendage emptying velocity (LAAeV) and filling velocity (LAAfV). Data analysis focused on identifying the morphology and location of thrombus or sludge. Patients were divided into the solid thrombus and sludge groups, and the correlation between clinical and echocardiographic variables and thrombotic status was analyzed.

RESULTS

Morphological classification: In total, thrombi were identified in 78 patients, including 71 (40.3%) mass and 7 (4.0%) lamellar, while sludge was noted in 98 (55.7%). Location classification: 92.3% (72/78) of patients had thrombus confined to the LAA; 3.8% (3/78) had both LA and LAA involvement; 2.7% (2/78) had LA, LAA and RAA extended into the RA, the remained 1.2%(1/78) was isolated to RAA. 98.0% (96/98) of patients had sludge confined to the LAA; the remaining 2.0% (2/98) were present in the atrial septal aneurysm, which protrusion of interatrial septum into the RA. The thrombus and sludge groups showed low LAAeV (19.43 ± 9.59 cm/s) or LAAfV (17.40 ± 10.09 cm/s). Only LA dimension ≥ 40 mm was independently associated with the thrombus state in the multivariable model.

CONCLUSION

This cohort study identified rare thrombus morphology and systematically summarized the classification of thrombus morphology. The distribution of thrombus and sludge outside limited to LAA was updated, including bilateral atrial and appendage involvement and rare atrial septal aneurysm sludge. LAAeV and LAAfV were of limited value in distinguishing solid thrombus from sludge.

CLINICAL TRIAL NUMBER

ChiCTR-OCH-13,003,729.

2023 Cardiac Society of Australia and New Zealand Expert Position Statement on Catheter and Surgical Ablation for Atrial Fibrillation

Catheter ablation for atrial fibrillation (AF) has increased exponentially in many developed countries, including Australia and New Zealand. This Expert Position Statement on Catheter and Surgical Ablation for Atrial Fibrillation from the Cardiac Society of Australia and New Zealand (CSANZ) recognises healthcare factors, expertise and expenditure relevant to the Australian and New Zealand healthcare environments including considerations of potential implications for First Nations Peoples. The statement is cognisant of international advice but tailored to local conditions and populations, and is intended to be used by electrophysiologists, cardiologists and general physicians across all disciplines caring for patients with AF. They are also intended to provide guidance to healthcare facilities seeking to establish or maintain catheter ablation for AF.

Artificial intelligence in detecting left atrial appendage thrombus by transthoracic echocardiography and clinical features: the Left Atrial Thrombus on Transoesophageal Echocardiography (LATTEE) registry

AIMS

Transoesophageal echocardiography (TOE) is often performed before catheter ablation or cardioversion to rule out the presence of left atrial appendage thrombus (LAT) in patients on chronic oral anticoagulation (OAC), despite associated discomfort. A machine learning model [LAT-artificial intelligence (AI)] was developed to predict the presence of LAT based on clinical and transthoracic echocardiography (TTE) features.

METHODS AND RESULTS

Data from a 13-site prospective registry of patients who underwent TOE before cardioversion or catheter ablation were used. LAT-AI was trained to predict LAT using data from 12 sites (n = 2827) and tested externally in patients on chronic OAC from two sites (n = 1284). Areas under the receiver operating characteristic curve (AUC) of LAT-AI were compared with that of left ventricular ejection fraction (LVEF) and CHA2DS2-VASc score. A decision threshold allowing for a 99% negative predictive value was defined in the development cohort. A protocol where TOE in patients on chronic OAC is performed depending on the LAT-AI score was validated in the external cohort. In the external testing cohort, LAT was found in 5.5% of patients. LAT-AI achieved an AUC of 0.85 [95% confidence interval (CI): 0.82-0.89], outperforming LVEF (0.81, 95% CI 0.76-0.86, P < .0001) and CHA2DS2-VASc score (0.69, 95% CI: 0.63-0.7, P < .0001) in the entire external cohort. Based on the proposed protocol, 40% of patients on chronic OAC from the external cohort would safely avoid TOE.

CONCLUSION

LAT-AI allows accurate prediction of LAT. A LAT-AI-based protocol could be used to guide the decision to perform TOE despite chronic OAC.

Predictive value of nutritional indices for left atrial thrombus in patients with valvular atrial fibrillation

BACKGROUND

The prognostic nutritional index (PNI) and geriatric nutritional risk index (GNRI) are well known indicators for adverse outcomes in various diseases, but there is no evidence on their association with the risk of left atrial thrombus (LAT) in patients with valvular atrial fibrillation (VAF).

METHODS

A comparative cross-sectional analytical study was conducted on 433 VAF patients. Demographics, clinical characteristics and echocardiographic data were collected and analyzed. Patients were grouped by the presence of LAT detected by transesophageal echocardiography.

RESULTS

LAT were identified in 142 patients (32.79%). The restricted cubic splines showed an L-shaped relationship between PNI and LAT. The dose-response curve flattened out near the horizontal line with OR = 1 at the level of 49.63, indicating the risk of LAT did not decrease if PNI was greater than 49.63. GNRI was negative with the risk of LAT and tended to be protective when greater than 106.78. The best cut-off values of PNI and GNRI calculated by receiver operating characteristics curve to predict LAT were 46.4 (area under these curve [AUC]: 0.600, 95% confidence interval [CI]:0.541-0.658, P = 0.001) and 105.7 (AUC: 0.629, 95% CI:0.574-0.684, P<0.001), respectively. Multivariable logistic regression analysis showed that PNI ≤ 46.4 (odds ratio: 2.457, 95% CI:1.333-4.526, P = 0.004) and GNRI ≤ 105.7 (odds ratio: 2.113, 95% CI:1.076-4.149, P = 0.030) were independent predictors of LAT, respectively.

CONCLUSIONS

Lower nutritional indices (GNRI and PNI) were associated with increased risk for LAT in patients with VAF.

P-wave parameters and their association with thrombi and spontaneous echo contrast in the left atrial appendage

BACKGROUND

The aim of this study was to examine the prevalence of abnormal P-wave parameters in patients with thrombus and/or spontaneous echo contrast (SEC) in the left atrial appendage (LAA), and to identify P-wave parameters particularly associated with thrombus and SEC formation.

HYPOTHESIS

We presume a significant relationship of P-wave parameters with thrombi and SEC.

METHODS

All patients in whom a thrombus or SEC was detected in the LAA on transoesophageal echocardiography were included in this study. Patients at risk (CHA2DS2-VASc Score ≥3) and routine transoesophageal echocardiography to exclude thrombi served as the control group. A detailed ECG analysis was performed.

RESULTS

Of a total of 4062 transoesophageal echocardiographies, thrombi and SEC were detected in 302 patients (7.4%). Of these patients, 27 (8.9%) presented with sinus rhythm. The control group included 79 patients. There was no difference in mean CHA2DS2-VASc score in the two groups (p = .182). A high prevalence of abnormal P-wave parameters was detected in patients with thrombus/SEC. Indicators for the presence of thrombi or SEC in the LAA were P-wave duration >118 ms (Odds ratio (OR) 3.418, Confidence interval (CI) 1.522-7.674, p < .001), P-wave dispersion >40 ms (OR 2.521, CI 1.390-4.571, p < .001) and advanced interatrial block (OR 1.431, CI 1.033-1.984, p = .005).

CONCLUSION

Our study revealed that several P-wave parameters are associated with thrombi and SEC in the LAA. The results may help identify patients who are at particularly high risk for thromboembolic events (e.g., in patients with embolic stroke of undetermined source).

The predictive value of the systemic immune-inflammatory index for left atrial appendage thrombus in non-valvular atrial fibrillation

OBJECTIVE

The systemic immune inflammatory index (SII) has prognostic value in cardiovascular diseases. The aim of current study was to investigate whether or not left atrial appendage (LAA) thrombus could be predicted by SII in patients with non-valvular atrial fibrillation.

METHOD

The study included 525 patients newly diagnosed with non-valvular atrial fibrillation, who had not previously had anticoagulant treatment (50.7% male, mean age 62.94±10.79 years). All patients underwent transoesophageal echocardiography.

RESULTS

LAA thrombus was observed in 86 patients (16.4%). In the ROC curve SII had a good diagnostic power in predicting LAA thrombus (AUC: 0.760, 95% CI: 0.703-0.818, P<0.001). In the multivariate regression analysis, diabetes (Hazard ratio: 2.264, 95% CI: 1.169-4.389, P=0.015), LAA emptying rate of <20 cm/s (Hazard ratio: 59.347, 95% CI: 25.397-138.680, P<0.001), and SII value of >750 (Hazard ratio: 4.291, 95% CI: 2.144-8.586 P<0.001) were determined as independent predictors for LAA thrombus. A poor correlation was found between SII and the CHADS2 VASc score (r=0.239, P<0.001) Conclusion: The SII, a practical and easily obtained test, can be used as a predictor of LAA thrombus in patients with non-valvular atrial fibrillation, and to decide on the anticoagulant treatment.

Risk factors for left atrial thrombus in younger patients (aged < 65 years) with atrial fibrillation or atrial flutter: Data from the multicenter left atrial thrombus on transesophageal echocardiography (LATTEE) registry

Background

Our aim was to assess the characteristics and to identify predictors of left atrial thrombus (LAT) in patients under age 65 with atrial fibrillation (AF) or atrial flutter (AFl).

Methods

We conducted a subanalysis of a multicenter, prospective, observational study [the LATTEE registry]. Consecutive AF/AFl patients referred for cardioversion or ablation were enrolled.

Results

Of the 3,109 patients included in the study, 1,276 were under age 65 (41%). Compared to non-LAT patients, those with LAT (n = 76) had higher CHA2DS2-VASc score (p < 0.001), more frequently had non-paroxysmal AF/AFl (p < 0.001), heart failure (p < 0.001), history of diabetes mellitus (p = 0.001), transient ischemic attack (p = 0.04), coronary artery disease (p = 0.02), and chronic kidney disease (p < 0.001). The LAT patients were also more often smokers (p = 0.004) and were more frequently treated with vitamin K antagonists (VKAs) (p < 0.001). Transthoracic echocardiography revealed a higher left atrial area (p < 0.001), lower left ventricular ejection fraction (LVEF) (p < 0.001), and lower value of LA appendage emptying volume in LAT than in non-LAT patients (p < 0.001). LVEF (OR 2.95; 95% CI: 1.32-6.59, p = 0.008), non-paroxysmal AF/AFl (OR 7.1; 95% CI: 2.05-24.63, p = 0.002) and treatment with VKAs (OR 4.92; 95% CI: 2.48-9.75, p < 0.001) were identified as independent predictors of LAT in younger patients.

Conclusions

Our study, which focused on younger patients with AF/AFl, indicated substantial clinical and echocardiographic differences between participants with and without LAT. In the AF/AFl patients younger than age 65, the independent predictors of LAT included non-paroxysmal AF/AFl, lower LVEF, and treatment with VKAs.