The association of systemic inflammation with atrial fibrillation and a pro-thrombotic state has received increasing attention recently, but whether this degree of inflammation provides additive value for prediction of clinical outcomes in adults with atrial fibrillation has not been established. In this issue of Heart, Hijazi and colleagues (see page 508) measured inflammatory biomarkers in over 14 thousand patients with atrial fibrillation in the Apixaban for Reduction In Stroke and Other Thromboembolic Events in Atrial Fibrillation (ARISTOTLE) trial. Cox regression was used to assess the relationship between outcomes at a mean follow-up of 1.9 years and baseline quartile groups of interleukin 6 (IL-6) and C reactive protein (CRP) levels. In these patients with atrial fibrillation who were anti-coagulated with apixaban or warfarin, IL-6 and CRP levels were not associated with an increased risk of stroke or systemic embolism and did not provide additive value to currently utilized risk scores. In contrast, both inflammatory biomarkers were significantly associated with an increased risk for all-cause mortality – the hazard ratio (HR) for IL-6 was 1.93 (1.57 to 2.37) and for CRP was 1.49 (1.24 to 1.79) when comparing the highest and lowest quartiles (figure 1), even after adjustment for clinical factors and other cardiovascular biomarkers.

The association of atrial fibrillation and systemic inflammation has clinical implications beyond predicting risk of adverse outcomes. If the risk of systemic embolization is simply …