However, there are very limited data to suggest that there would be any incremental clinical bene t in risk prediction, and moreover there is no evidence that management (in terms of oral anticoagulant [OAC]) would be changed.57 Nevertheless, the most consistent independent predictor of ischemic stroke on TTE is the presence of moderate- severe left ventricular systolic dysfunction. In patients undergoing transesophageal echocardiography (TEE), and left atrial spontaneous echo are both associated with increased thromboembolism, as well as the presence of low LAA velocities and complex aortic plaque; however, the same limitations as for TTE parameters apply.57 Biomarkers: e-Table 5 summarizes important studies involving currently available biomarkers ( biological markers ) that have shown associations with stroke and thrombosis in AF, but both study design and scale of the studies limit possible conclusions. Caveats with the use of these biomarkers include the inter- and intra-patient and assay variability; some have a diurnal variation and can be highly in uenced by associated comorbidities and drug therapies. Many biomarkers are nonspeci c for a particular end point and can be equally predictive not only of stroke but bleeding, death, hospitalization, HF, etc, as well as noncardiac conditions (eg, glaucoma). The importance of biomarkers probably lies in the very low risk strata of clinical scores (eg, CHA2DS2-VASc 0-1 group) where they may in uence the decision to anticoagulate, yet there are limited data available in these patients. There are several other hurdles, including variations in availability in health-care systems, biomarker assays, access to laboratories, biomarkers diurnally, by comorbidities and by anticoagulation and other therapies. For these reasons, the clinical application of biomarkers in management of AF is unlikely to be signi cant. 