Perspective:

The following are key points from a review article on biomarkers in atrial fibrillation (AF):

1. Serum biomarkers may help in the following aspects of AF: refinement of stroke risk beyond that offered by clinical and echocardiographic risk factors, prediction of AF in those without any history of AF, and elucidation of the pathogenesis of AF.

2. In comparison with CHADS₂ and CHA₂DS₂-VASc scores, when adding information about troponin measurements to a predictive model for stroke outcomes, cardiac troponin levels provide incremental prognostic information.

3. Elevated B-type natriuretic peptide (BNP) levels may be useful in predicting stroke risk in patients with AF on anticoagulation.

4. BNP levels may predict the likelihood of subsequent identification of AF for patients with cryptogenic stroke.

5. Results from the Cardiovascular Health Study demonstrated that N-terminal proBNP is a considerably stronger marker for predicting incident AF, when compared to clinical and echocardiographic covariates.

6. Cystatin C is considered to be a more reliable marker of renal function than serum creatinine because it is freely filtered by the glomerulus, not affected by tubular secretion, and minimally influenced by disease states. In the ARISTOTLE and RE-LY biomarker substudies, rising cystatin C levels were independently associated with increased rates of stroke or systemic embolism, mortality, and major bleeding.

7. Although renal impairment (measured with either creatinine-based equations or cystatin C) constitutes a major risk factor for thromboembolic and cardiovascular events in AF, it is not represented in current models for risk stratification.

8. As confirmed in the recent ARISTOTLE biomarker study, D-dimer levels at baseline, regardless of ongoing vitamin K antagonist therapy, are related to stroke, mortality, and major bleeding.

9. Some controversy aside, most studies have reported elevated levels of C-reactive protein or other inflammatory markers to be independent risk factors for the incidence of AF in subjects with no history of AF.

10. Future directions include the use of multimarker-based risk stratification and the role of biomarkers in predicting treatment response and treatment selection.