A recent human study in patients admitted to hospital with critical heart failure showed that elevated phenylalanine predicted 1 year all-cause mortality independent of several traditional risk factors (age, atrial fibrillation, cholesterol), mortality scores (SOFA, APACHE II), and inflammatory markers (CRP, transferrin, IL-8, IL-10) (21). Here, CXCL8 is linked to atrial fibrillation.