Nomogram for predicting left atrial appendage dense spontaneous echo contrast and/or thrombosis (dense spontaneous echo contrast/left atrial appendage thrombus): a comparison with CHADS2 and CHA2DS2-VASc scores based on three-dimensional transesophageal echocardiography

Figures

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  Figure 1. Flowchart of the study. CHA2DS2-VASc, congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, prior stroke/TIA, vascular disease, age 65–74 years, sex category score. CHADS2, congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, prior stroke/TIA score. AUC, area under the receiver operating characteristic curve; DCA, decision curve analysis; LAA, left atrial appendage; LAAT, left atrial appendage thrombus; NVAF, non-valvular atrial fibrillation; SEC, spontaneous echo contrast; TEE, transesophageal echocardiography; TIA, transient ischemic attack.

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  Figure 2. Representative 3D-TEE images of patients in the non-dense SEC/LAAT group (A) and the dense SEC/LAAT group (B). 3D-TEE, three-dimensional transesophageal echocardiography; SEC/LAAT, spontaneous echo contrast/left atrial appendage thrombus.

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  Figure 3. Receiver operating characteristic curves of predictions by the three models. Model 1, Self-developed Model. Model 2, CHADS2 Score. Model 3, CHA2DS2-VASc Score. AUC, area under the receiver operating characteristic curve.

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  Figure 4. Calibration curves of predictions by the three models. The dashed diagonal line indicates perfect consistency between the predicted probability and the observed probability (perfect calibration). The calibration curve of Model 1 is closest to the diagonal, indicating its optimal calibration. All models show a mild overestimation trend in the high-risk region (predicted probability >0.6). Model 1, Self-developed Model. Model 2, CHADS2 Score. Model 3, CHA2DS2-VASc Score.

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  Figure 5. Box plots of core metrics derived from 10-fold cross-validation. Brier, Brier score; C (ROC), area under the receiver operating characteristic curve; Eavg, average calibration error; Emax, maximum calibration error; R2, coefficient of determination.

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  Figure 6. This nomogram integrates four independent predictive factors: D-dimer >0.550 mg/L, LAA orifice morphology, LAA poor echogenicity, and EHRA score ≥IIb. In use, the corresponding score (points) is determined on each variable axis according to the patient’s condition, and the total score (total points) is projected onto the risk axis at the bottom (risk of event) to read the individualized predicted risk probability. EHRA, European Heart Rhythm Association; LAA, left atrial appendage.

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  Figure 7. Receiver operating characteristic curve of the predictive model. The area under the curve (AUC, i.e., C-statistic) of this model is AUC: 0.892 (95% CI: 0.839–0.945), indicating that the model has excellent discriminative ability. The gray shaded area represents its 95% CI. AUC, area under the receiver operating characteristic curve; CI, confidence interval.

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  Figure 8. Decision curve analysis of the predictive model. This figure evaluates the net benefit of using the model to guide clinical decisions (Model) compared with two reference strategies at different threshold probabilities. The reference strategies include intervening in all patients (All) and intervening in no patients (None). Within the interval demarcated by the two orange vertical dashed lines (3% and 97%), the model yields higher net benefit than the two reference strategies, indicating favorable clinical utility. The red‑shaded band represents the model‑relevant interval, and the blue‑shaded segments represent model‑irrelevant intervals for auxiliary interpretation.

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  Figure 9. Clinical impact curve of the predictive model. Four curves are presented in this plot. The red curve (number high-risk) represents the number of patients classified as high-risk by the model at different risk thresholds. The blue curve (number high-risk with event) represents the number of true-positive patients who actually experienced dense SEC/LAAT among those classified as high-risk. The upper shaded red curve indicates the total number of screened patients, and the lower shaded blue curve represents high-risk patients without events. This curve helps balance the benefits (detecting true positives) and costs (unnecessary intervention for false positives) of intervention at different thresholds. SEC/LAAT, spontaneous echo contrast/left atrial appendage thrombus.