For these reasons, the clinical application of biomarkers in management of AF is unlikely to be signi cant. Other Potential Novel Risk Factors for Ischemic Stroke in AF: As with established risk factors, novel risk factors may improve prediction of thromboembolic risk in AF patients, where current risk scores are These novel factors include clinical risk factors (eg, burden of AF), serum biomarkers (eg, N-terminal pro B-type natriuretic peptide), imaging (eg, left atrial brosis on cardiac MRI), and echocardiography (eg, left atrial volume index and longitudinal strain). However, these factors are currently neither proven to signi cantly add to risk prediction, nor likely to in uence the decision to anticoagulate. Risk Strati cation for Stroke and Thromboembolism in AF: A comparison of features included in various published stroke risk strati cation schemes in AF is shown in e-Table 6. A summary of studies comparing the various stroke risk strati cation schema is available in e-Table 7. The risk strati cation scheme commonly used in many guidelines is the CHA2DS2-VASc (congestive heart failure, hypertension, age $ 75 years [doubled], diabetes, stroke/TIA/thromboembolism [doubled], vascular disease [prior myocardial infarction (MI), peripheral arterial disease (PAD), or aortic plaque], age 65-74 years, sex category [female]) score.1 All risk schemes based on clinical risk factors have broadly similar predictive value for high risk patients who sustain stroke and thromboembolism events (all c-indexes approximately 0.60-0.65). Adding more and more clinical variables and complexity (ie, simple vs more complex clinical risk scores) would only modestly increase the c-index to approximately 0.65 to 0.70. Many score comparisons focus on identi cation of high risk and do not focus on low risk end of the spectrum and so are not helpful for decision-making on whether to anticoagulate. 