Nomogram to Predict Left Atrial Thrombus or Spontaneous Echo Contrast in Patients With Non-valvular Atrial Fibrillation

The role of multi-modality imaging for the assessment of left atrium and left atrial appendage: a clinical consensus statement of the European Association of Cardiovascular Imaging (EACVI), European Heart Rhythm Association (EHRA) of the European Society of Cardiology (ESC)

Structural, architectural, contractile, or electrophysiological alterations may occur in the left atrium (LA). The concept of LA cardiopathy is supported by accumulating scientific evidence demonstrating that LA remodelling has become a cornerstone diagnostic and prognostic marker. The structure and the function of the LA and left atrial appendage (LAA), which is an integral part of the LA, are key elements for a better understanding of multiple clinical conditions, most notably atrial fibrillation, cardioembolism, heart failure, and mitral valve diseases. Rational use of various imaging modalities is key to obtain the relevant clinical information. Accordingly, this clinical consensus document from the European Association of Cardiovascular Imaging, in collaboration with the European Heart Rhythm Association, provides comprehensive, up-to-date, and evidence-based guidance to cardiologists and cardiac imagers for the best practice of imaging LA and LAA for the diagnosis, management, and prognostication of the patients.

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.

Predictive indicators in peripheral blood and left atrium blood for left atrial spontaneous echo contrast in atrial fibrillation patients

OBJECTIVES

The purpose of this study was to demonstrate the discriminating predictive indicators in peripheral blood and left atrium blood for predicting the risk of left atrial spontaneous echo contrast (LASEC) in atrial fibrillation patients underwent catheter ablation.

METHODS

A total of 108 consecutive AF patients treated with radiofrequency ablation between July 2022 and July 2023 were enrolled and divided into two groups based on preprocedural transesophageal echocardiography: the non LASEC group (n = 71) and the LASEC group (n = 37). Circulating platelet and endothelial- derived MPs (PMPs and EMPs) in peripheral blood and left atrial blood were detected. Plasma soluble P-selectin (sP-selectin) and von Willebrand factor (vWF) were observed. Diagnostic efficiency was measured using receiver operating characteristic (ROC) curve.

RESULTS

Peripheral sP-selectin, vWF and EMPs expressions elevated in all subjects when compared to those in left atrium blood. Levels of sP-selectin and vWF were significantly higher in peripheral blood of LASEC group than those of non LASEC group (p = 0.0018,p = 0.0271). Significant accumulations of peripheral PMPs and EMPs were documented in LASEC group by comparison with non LASEC group (p = 0.0395,p = 0.018). The area under curve(AUC) of combined PMPs and sP-selectin in predicting LASEC was 0.769 (95%CI: 0.678-0.845, sensitivity: 86.49%, specificity: 59.15%), significantly larger than PMPs or sP-selectin alone.

CONCLUSIONS

Expressions of PMPs, sP-selectin, EMPs and vWF Increased in NVAF patients with LASEC and that might be potential biomarkers for LASEC prediction.

Nomogram to predict recurrence risk factors in patients with non-valvular paroxysmal atrial fibrillation after catheter radiofrequency ablation

BACKGROUND

Radiofrequency catheter ablation (RFCA) is an effective method for controlling the heart rate of paroxysmal atrial fibrillation (PAF). However, recurrence is trouble under the RFCA. To gain a deeper understanding of the risk factors for recurrence in patients, we created a nomogram model to provide clinicians with treatment recommendations.

METHODS

A total of two hundred thirty-three patients with PAF treated with RFCA at Guizhou Medical University Hospital between January 2021 and December 2022 were consecutively included in this study, and after 1 year of follow-up coverage, 166 patients met the nadir inclusion criteria. Patients with AF were divided into an AF recurrence group and a non-recurrence group. The nomogram was constructed using univariate and multivariate logistic regression analyses. By calculating the area under the curve, we analyzed the predictive ability of the risk scores (AUC). In addition, the performance of the nomogram in terms of calibration, discrimination, and clinical utility was evaluated.

RESULTS

At the 12-month follow-up, 48 patients (28.92%) experienced a recurrence of AF after RFCA, while 118 patients (71.08%) maintained a sinus rhythm. In addition to age, sex, and TRV, LAD, and TTPG were independent predictors of recurrence of RFCA. The c-index of the nomogram predicted AF recurrence with an accuracy of .723, showing good decision curves and a calibrated nomogram, as determined by internal validation using a bootstrap sample size of 1000.

CONCLUSION

We created a nomogram based on multifactorial logistic regression analysis to estimate the probability of recurrence in patients with atrial fibrillation 1 year after catheter ablation. This plot can be utilized by clinicians to predict the likelihood of recurrence.

A nomogram for predicting left atrial thrombus or spontaneous echo contrast in non-valvular atrial fibrillation patients using hemodynamic parameters from transthoracic echocardiography

Background

Atrial fibrillation (AF) is the most common cardiac arrhythmia and is associated with a high risk of stroke. This study was designed to investigate the relationship between hemodynamic parameters and left atrial thrombus/spontaneous echo contrast (LAT/SEC) in non-valvular atrial fibrillation (NVAF) patients and establish a predictive nomogram that integrates hemodynamic parameters with clinical predictors to predict the risk of LAT/SEC.

Methods

From January 2019 to September 2022, a total of 354 consecutive patients with NVAF were enrolled in this cross-sectional study at the First Affiliated Hospital of Guangxi Medical University. To identify the optimal predictive features, we employed least absolute shrinkage and selection operator (LASSO) regression. A multivariate logistic regression model was subsequently constructed, and the results were visualized with a nomogram. We evaluated the model's performance using discrimination, calibration, and the concordance index (C-index).

Results

We observed a 38.7% incidence of SEC/TH in NVAF patients. Independent influencing factors of LAT/SEC were identified through LASSO and multivariate logistic regression. Finally, four indicators were included, namely, previous stroke/transient ischaemic attack (OR = 4.25, 95% CI = 1.57-12.23, P = 0.006), left atrial volume index (LAVI) (OR = 1.04, 95% CI = 1.01-1.06, P = 0.001), S/D ratio (OR = 0.27, 95% CI = 0.11-0.59, P = 0.002), and left atrial acceleration factor (OR = 4.95, 95% CI = 2.05-12.79, P = 0.001). The nomogram, which incorporated these four influencing factors, demonstrated excellent predictive ability. The training set had a C-index of 0.878, while the validation set had a C-index of 0.872. Additionally, the calibration curve demonstrated great consistency between the predicted probabilities and the observed outcomes, and the decision curve analysis confirmed the important clinical advantage of the model for patients with NVAF.

Conclusion

Our findings indicate that an enlarged left atrium and abnormal hemodynamic parameters in the left atrial and pulmonary veins are linked to a greater risk of LAT/SEC. Previous stroke/transient ischaemic attack, LAVI, the S/D ratio, and left atrial acceleration factor were independently associated with LAT/SEC in NVAF patients. With the incorporation of these four variables, the developed nomogram effectively predicts the risk of LAT/SEC and outperforms the CHA2DS2-VASc score.

In-stent restenosis after vertebral artery origin stenosis stenting: a nomogram for risk assessment

OBJECTIVE

To propose a nomogram for individual risk assessment of in-stent restenosis (ISR) after vertebral artery origin stenosis (VAOS) stenting.

METHODS

We included 793 patients with VAOS treated with stenting from October 2006 to May 2013, with a median follow-up of 27.8 months. Cox regression and the least absolute shrinkage and selection operator (LASSO) regression were adopted for variable selection. The nomogram was formulated and validated by concordance indexes (C-indexes) and calibration curves. An in-stent restenosis risk table (ISR-RT) was subsequently generated for risk stratification. Differences between low-, intermediate-, and high-risk levels were shown by Kaplan-Meier curves and compared by log-rank test.

RESULTS

The training and validation set included 594 and 199 patients, with a mean ISR rate of 37.2% and 35.2%, respectively. Stent type (HR=1.64, 95% CI 1.26 to 2.14), stent diameter (HR=2.48, 95% CI 1.77 to 3.48), history of peripheral vascular disease (HR=2.17, 95% CI 1.17 to 4.00), history of transit ischemic attack (HR=1.45, 95% CI 1.05 to 2.14), and left-side involvement (HR=1.33, 95% CI 1.04 to 1.69) were included in the nomogram. The C-indexes at 6 and 12 months were 0.650 and 0.611 in the training set, and 0.713 and 0.603 in the validation set, respectively. Compared with low-risk patients, the intermediate- and high-level group had 1.46 (95% CI 1.05 to 2.04; p=0.0235) and 2.28 (95% CI 1.64 to 3.17; p<0.0001) higher chances of developing ISR in 2 years, respectively.

CONCLUSIONS

A nomogram and a risk evaluation table were developed with good predictive ability for in-stent restenosis among patients with VAOS, which could serve as a practical approach for individualized risk evaluation.

Finding low CHA2DS2-VASc scores unreliable? Why not give morphological and hemodynamic methods a try?

Patients with atrial fibrillation (AF) suffer from a high risk of thrombosis. Currently, the CHA2DS2-VASc score is the most widely used tool for risk stratification in patients with AF, but it has disappointing accuracy and limited predictive value, especially in those with low scores. Thrombi in patients with AF mostly grow in their left atrial appendages (LAA), which is directly related to the abnormal morphology of the LAA or the left atrium and the unusual hemodynamic state around LAA, which may sensitively evaluate the risk of thrombosis complications in patients with AF and bring bases to clinical plans of medication and operation. Therefore, we investigated the research progress of hemodynamic and morphological studies about the predictive value of thrombosis risk in patients with AF, intending to discuss the prediction potential of morphological and hemodynamic indexes when compared with the presently used CHA2DS2-VASc system and how to build a more precise thromboembolic event prediction model for patients with AF.

Severe Left Atrial Spontaneous Echo Contrast in Nonvalvular Atrial Fibrillation: Clinical Characteristics and Impact on Ischemic Risk Postablation

BACKGROUND

 Spontaneous echo contrast (SEC) is an important precursor for intracardiac thrombus and stroke. There are very limited data on characteristics of severe SEC and its impact on ischemic risk of nonvalvular atrial fibrillation (NVAF) patients after radiofrequency catheter ablation.

METHODS

 Transesophageal echocardiography files were reviewed between March 2009 and March 2021 in this monocentric retrospective study. SEC was classified into four levels. The primary endpoint was thromboembolic event (stroke, myocardial infarction, systemic embolism, and ensuing death), and the secondary endpoint included nonischemic mortality and recurrent atrial arrhythmia.

RESULTS

 Six hundred SEC cases were enrolled and classified into mild SEC group (Grade 1-2, n = 515) and severe SEC group (Grade 3-4, n = 85). Independent risk factors for severe SEC included higher brain natriuretic peptide (BNP), erythrocyte sedimentation rate (ESR), and LAd/∆LVED (LAd = left atrial diameter; ∆LVED = left ventricular end-diastolic diameter - left ventricular end-systolic diameter). The severe SEC group had a higher peri-procedural ischemic event occurrence (7.1 vs. 1.9%, p = 0.007). At a median follow-up of 55 months, the severe SEC group had a lower freedom rate from ischemic events (90.1 vs. 75.3%, p < 0.001); older age and severe SEC were independent risk factors for ischemic events. In patients undergoing redo-procedure (n = 100), a remarkably reduced ESR (17.8 ± 12.0 vs. 28.2 ± 19.0 mm/h, p < 0.001) was observed in patients whose SEC disappeared.

CONCLUSIONS

 Higher BNP, ESR, and LAd/∆LVED were the independent predictors for severe SEC. Severe SEC was associated with higher peri-procedural and long-term ischemic risks. ESR and LAd/∆LVED, as indicators of hematological and hemodynamic change, seemed helpful in identifying NVAF patients prone to developing severe SEC.

Atrial cardiomyopathy markers predict ischemic cerebrovascular events independent of atrial fibrillation in patients with acute myocardial infarction

Background

Contemporary data on atrial cardiomyopathy (ACM) markers and ischemic cerebrovascular events (ICVE) in patients with acute myocardial infarction (AMI) is lacking. We aimed to examine whether ACM markers predict ICVE among AMI patients.

Materials and methods

A total of 4,206 AMI cases diagnosed in clinical examinations between January 2016 and June 2021 were assessed for markers of ACM including B-type natriuretic peptide (BNP), P-wave terminal force in ECG lead V1 (PTFV1), and left atrium diameter (LAD). Left atrial enlargement (LAE) and abnormal PTFV1 were defined by previously published cut-off points. The primary outcome was incident ICVE composed of ischemic stroke (IS) and transient ischemic attack (TIA). Receiver operating curve analyses were used to compare the predictive performance of the CHA2DS2-VASc score combined with ACM markers to the CHA2DS2-VASc score alone.

Results

During a median follow-up of 44.0 months, 229 (5.44%) ICVE occurred. Of these, 156 individuals developed IS and the remaining 73 cases were diagnosed with TIAs. The ICVE group showed larger PTFV1 and increased LAD as well as elevated BNP levels at baseline. In the multivariate analysis, we found significant associations with ICVE for PTFV1 (HR per 1,000 μV*ms, 1.143; 95% CI, 1.093–1.196), LAD (HR per millimeter, 1.148; 95% CI, 1.107–1.190), but not BNP after adjusting for known ICVE risk factors and interim atrial fibrillation (AF). The addition of abnormal PTFV1 and LAE improved the predictive accuracy of the CHA2DS2-VASc score with C-statistic increasing from 0.708 to 0.761 (p &lt; 0.001).

Conclusion

Atrial cardiomyopathy markers including PTFV1 and LAD were associated with incident ICVE independent of well-established risk factors and AF occurrence. The addition of ACM markers with CHA2DS2-VASc score may well discriminate individuals at high risk of ICVE in AMI patients.

Development and Validation of a Nomogram for Estimation of Left Atrial Thrombus or Spontaneous Echo Contrast Risk in Non-Valvular Atrial Fibrillation Patients with Low to Borderline CHA2DS2-VASc Score

Purpose

Left atrial thrombus (LAT)/left atrial spontaneous echo contrast (LASEC) still exists in CHA₂DS₂-VASc score-defined low/borderline risk population. The purpose of this study is to explore the risk factors that associate with LAT/SEC and to create a nomogram to predict LAT/SEC risk in NVAF patients with low/borderline CHA₂DS₂-VASc scores.

Patients and Methods

A total of 834 NVAF patients with complete data on transesophageal echocardiography (TEE) were included in this study. Univariate and multivariate logistic regression analyses were performed to identify the risk factors that associate with LAT/SEC, and a nomogram was established based on the results. Receiver operating characteristic curve (ROC), calibration curve and decision curve analysis were performed to verify the predictive power of nomogram.

Results

The rates for LAT/SEC for the training and validation cohorts were 84 (14.7%) and 30 (11.4%), respectively. Independent factors including age, left ventricular ejection fraction (LVEF), left atrial diameter (LAD), smoke, non-paroxysmal AF (NPAF), and E/e’ were considered to construct the nomogram for LAT/SEC. The AUC for nomogram was 0.839 and 0.811 in the training and validation cohorts, respectively. The calibration and decision curve analysis showed that the nomogram had a good prediction capacity and would be clinically useful.

Conclusion

Age, LVEF, LAD, smoke, NPAF, and E/e’ are independently associated with LAT/SEC in NVAF patients with low/borderline CHA₂DS₂-VASc scores. The nomogram that incorporates these six variables effectively predict LAT/SEC risk in NVAF patients with low/borderline CHA₂DS₂-VASc scores.

A nomogram to predict left atrial appendage thrombus and spontaneous echo contrast in non-valvular atrial fibrillation patients

Background

Non-valvular atrial fibrillation (NVAF) significantly increases the risk of stroke. Although there is availability of prediction models, their ability to predict the risk of stroke in NVAF patients remains suboptimal. Therefore, there is need to improve prediction of high-risk individuals, which is critical for efficient management of patients with NVAF.

Objective

The objective of our paper is to develop a nomogram for predicting the risk of left atrial appendage thrombus (LAAT) and spontaneous echo contrast (SEC), thereby replacing the risk of stroke in NVAF patients.

Design

This was a retrospective cohort study that analyzed clinical data and echocardiographic indices of 387 patients with NVAF from October 2018 to June 2021. Multivariable logistic regression was used to evaluate independent factors that were used to construct the prediction nomogram.

Analysis

The discriminative ability and calibration of the nomogram to predict LAAT/SEC were tested using C-statistic and calibration plot. The performance of the nomogram was assessed against the CHA2DS2 score, CHA2DS2-VASc score and ATRIA score using the receiver operating characteristic curve (ROC), decision curve analysis (DCA), integrated discrimination index (IDI) and net reclassification index (NRI).

Result

Out of the total 387 patients enrolled in this study, 232 had LAAT/SEC. Multivariable analyses demonstrated that N-terminal pro-B-type natriuretic peptide (NT-proBNP), albumin (ALB), LAA ejection fraction (LAAEF) and LAA global peak longitudinal strain (LAA GPLS) were independent predictors of LAAT/SEC. The constructed nomogram had good discriminative (C = 0.886) and calibration (0.876) abilities after bias correction by the C-index. Compared with other models, the decision curve analyses demonstrated that the nomogram had greater net benefits. Besides, the nomogram had significant improvement in predictive performance, sensitivity and reclassification for LAAT/SEC compared with the CHA2DS2 [(c-index: 0.886 vs. 0.576, p < 0.05), (NRI: 0.539, p < 0.05), (IDI: 0.432, p < 0.05)], CHA2DS2-VASc [(c-index: 0.886 vs0.579, p < 0.05), (NRI: 0.513, p < 0.05), (IDI: 0.432, p < 0.05)] or ATRIA [(c-index: 0.886 vs0.583, p < 0.05), (NRI: 0.546, p < 0.05), (IDI: 0.432, p < 0.05)].

Conclusion

Taken together, our data demonstrated that the developed nomogram was effective and had potential clinical application in the prediction of LAAT/SEC in patients with NVAF.