Can transesophageal echocardiography be safely deferred? A low-cost predictive model using D-dimer to exclude left atrial thrombus in treatment-naïve rheumatic mitral stenosis.

BACKGROUND: Transesophageal echocardiography (TEE) is the reference standard for excluding left atrial thrombus (LAT) in rheumatic severe mitral stenosis (SMS), yet its availability is limited in many low-resource settings. A reliable, low-cost strategy to safely defer TEE would have a significant clinical impact. This study evaluated whether D-dimer-based predictive models can accurately exclude newly detected LAT in treatment-naïve patients with rheumatic SMS. METHODS: Sixty-eight consecutive patients with rheumatic SMS who were not receiving anticoagulation underwent D-dimer testing, transthoracic echocardiography, and TEE. Associations with LAT were assessed using conventional and Firth-penalized logistic regression. Diagnostic performance was evaluated using receiver operating characteristic analysis with 1,000-bootstrap internal validation. Two composite models were examined: D-dimer combined with atrial fibrillation (AF) and D-dimer combined with mitral valve area (MVA). RESULTS: LAT was newly detected in 12 patients (17.6%). D-dimer levels were significantly higher in LAT-positive patients (943.5 vs. 168.5 ng/mL, p < 0.001). The optimal D-dimer cut-off (360.6 ng/mL) achieved 100% sensitivity, 71.4% specificity, and an optimism-corrected AUC of 0.935, outperforming the conventional 500 ng/mL threshold (sensitivity 75%). In adjusted models, D-dimer remained a strong independent predictor of LAT (per SD: AOR 6.91; 95% CI 2.72-17.54). Composite models demonstrated similarly high discrimination (AUC 0.933-0.940); adding AF did not improve performance, whereas incorporating MVA increased specificity to 100%. CONCLUSIONS: D-dimer may help exclude LAT in treatment-naïve patients with rheumatic SMS. Its potential role in supporting more selective TEE use in resource-limited settings warrants further evaluation in larger prospective multicenter studies.