Differences in D-dimer Blood Concentration in Atrial Fibrillation Patients with Left Atrial Thrombus or Severe Left Atrial Spontaneous Echo Contrast

Background: Severe left atrial spontaneous echo contrast (SLASEC) is considered the prior stage to thrombosis. Studies have suggested an effect of D-dimer blood concentration on exclusion of left atrial thrombus (LAT), but it remains unclear whether D-dimer concentrations differ between atrial fibrillation (AF) patients with SLASEC or LAT. Methods: Nonvalvular AF patients scheduled to undergo catheter ablation or cardioversion between January 2017 and July 2020 were screened for this prospective study. All patients underwent transesophageal echocardiography (TEE) to detect SLASEC or LAT. Results: 35 patients with SLASEC and 22 patients with LAT were detected. D-dimer concentration and CHA 2 DS 2 -VASc score were significantly lower in the SLASEC group compared with the LAT group (D-dimer: 0.26±0.13 vs. 0.87±0.9 mg/L, P<0.001; CHA 2 DS 2 -VASc score: 2.3±0.9 vs. 3.1±1.5, P =0.02). The cut-off value for D-dimer concentration (0.285 mg/L) had sensitivity of 77.3% and specificity of 80.0% for prediction of LAT. D-dimer concentration showed a decreasing trend with a significant difference after complete thrombus resolution in the LAT group by anticoagulation treatment. No ischemic stroke, or systemic thromboembolism events occurred in the SLASEC group during the 6-month follow-up. Conclusions: This study demonstrated a significantly lower D-dimer concentration and CHA2DS2 -VASc score in AF patients with SLASEC than in those with LAT. The D-dimer cut-off value (0.285 mg/L) can be used as an effective reference index to distinguish the pre-thrombotic state of LAT from LAT. D-dimer blood concentration may be a predictor of LAT thrombolysis.