Differences in D-dimer blood concentration in atrial fibrillation patients with left atrial thrombus or severe left atrial spontaneous echo contrast

Purpose Severe left atrial spontaneous echo contrast (SLASEC) is considered the prior stage to thrombosis and a high-risk factor for thrombotic events. 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 in Shanghai Ruijin Hospital between January 2017 and July 2020 were screened for this prospective study. All patients underwent transesophageal echocardiography (TEE) to detect SLASEC or LAT. D-dimer concentrations were measured at the time of TEE. Clinical data including CHA(2)DS(2)-VASc score were evaluated. Major complications with thromboembolism in the SLASEC group were followed up at least 6 months after therapy. Results Among 920 consecutively enrolled nonvalvular AF patients, 30 patients with SEC grade 0, 35 patients with SLASEC, and 22 patients with LAT were included. 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. 0.86 +/- 0.9 mg/L, P<0.05; 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 (0.42 +/- 0.22 vs. 0.33 +/- 0.18 mg/L, P=0.03) for 9 patients in the LAT group after complete thrombus resolution by anticoagulation treatment. No major or fatal bleeding, 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 CHA(2)DS(2)-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.