Carnevale R, et al. - Researchers aimed to develop an assay measuring serum hydrogen peroxide (H₂O₂) break-down activity (HBA) of healthy subjects (HS). They validated the assay in a cohort of patients with atrial fibrillation (AF). The developed assay easily measured serum HBA, which was linked to cardiovascular events (CVEs) in AF patients, and could be an additional useful tool for cardiovascular risk stratification. As per multivariable Cox's proportional hazards regression analysis, age group 3 (71–80 years), age group 4 (>80 years), diabetes, previous cardiac events and HBA (below median) forecast CVEs.