Relevance of transthoracic left atrial appendage wall velocity measurement in addition to left atrial volume for noninvasive and quantitative assessment of left atrial thrombogenesis in patients with atrial fibrillation and normal D-dimer levels

Diagnostic accuracy of D-dimer to detect left atrial thrombus in patients with atrial fibrillation: A systematic review and meta-analysis

BACKGROUND

There is conflicting evidence about the use of biomarkers to diagnose left atrial thrombus in patients with atrial fibrillation.

OBJECTIVE

The purpose of this study was to assess the diagnostic accuracy of D-dimer to detect left atrial thrombus in patients with atrial fibrillation.

METHODS

We searched 4 electronic databases from inception to December 16, 2020. The reference standard was left atrial thrombus detected by transesophageal echocardiography. Study quality was assessed with the Quality Assessment of Diagnostic Accuracy Studies 2 tool. We used a bivariate model to calculate the pooled sensitivity and specificity with their 95% confidence intervals (CIs). The optimal cutoff and predictive values were also estimated.

RESULTS

Eleven cross-sectional studies involving 4380 patients were included. The median prevalence of left atrial thrombus was 12%. In 7 studies, the pooled sensitivity of D-dimer at 500 ng/mL was 50% (95% CI 26%-74%) and the pooled specificity was 88% (95% CI 76%-95%). The pooled sensitivity of age-adjusted D-dimer was 36% (95% CI 14%-66%) and the pooled specificity was 99% (95% CI 96%-99%) in 2 studies. The optimal cutoff of D-dimer was 390 ng/mL in 10 studies with a pooled sensitivity of 68% (95% CI 44%-85%) and a pooled specificity of 73% (95% CI 54%-86%). The positive and negative predictive values were 21.8% and 95.4%, respectively. The risk of bias was low or unclear for all domains. Concerns about applicability were low for almost all studies.

CONCLUSION

Our meta-analysis suggests that D-dimer has the potential to be useful to rule out left atrial thrombus in patients with atrial fibrillation.

Plasma fibrin D-dimer and the risk of left atrial thrombus: A systematic review and meta-analysis

BACKGROUND

Plasma fibrin d-dimer has been taken as a marker for thrombus. The aim of this study was to evaluate the relationship between d-dimer (DD) levels and left atrial spontaneous echo contrast (SEC)/left atrial thrombus (LAT).

METHODS

We identified clinical studies by systematic search of MEDLINE and EMBASE databases up to Feb 2016. All observational studies that considered DD as a study factor and trans-esophageal echocardiography (TEE) identified SEC/LAT as an outcome were included. Two reviewers independently selected the studies and extracted the data.

RESULTS

Of the 21 included studies, 16 studies (2652 patients) have compared the mean DD differences between patients with and without an evidence of the presence of SEC/LAT, 9 studies (1667 patients) have estimated the diagnostic value of DD in the presence of LAT, and 11 studies (1856 patients) have available information to calculate a ratio of the presence of LAT among individuals in the top and the bottom third of DD levels. The pooled standardized mean difference (SMD) of DD between patients with and without left atrial SEC and/or LAT was 1.29 [95%CI: 0.51, 2.08], with SMDs of 0.42 [95% CI: 0.08, 0.77] and 2.34 [95% CI: 1.01, 3.68] in SEC/LAT and LAT subgroups, respectively. The combined risk ratio of the presence of LAT among individuals between the top of the distribution of DD levels and that in the bottom third was 3.84 [95% CI: 2.35, 6.28], associating with a mean difference of 0.78 ug/ml (1.10 vs 0.32 ug/ml). The pooled sensitivity, specificity and positive likelihood ratio of DD for LAT were 0.75 [95% CI: 0.65, 0.83], 0.81 [95% CI: 0.59, 0.93] and 4.0 [95% CI: 1.7, 9.9], respectively.

CONCLUSIONS

High plasma fibrin DD was associated with left atrial SEC/LAT, particularly among patients with LAT. DD levels have moderate sensitivity and specificity for diagnosing LAT.