Kaplan RM, et al. - Researchers analyzed patients with cardiovascular implantable electronic devices (CIED) to assess rates of stroke and systemic embolism (SSE) as a function of both CHA₂DS₂-VASc score and atrial fibrillation (AF) duration. They joined data from the Optum electronic health record de-identified database (2007-2017) to the Medtronic CareLink database of CIEDs able of continuous AF monitoring. This study included 21,768 non-anticoagulated CIED patients of 68.6 ± 12.7 years, 63% were male. Significant associations of both increasing AF duration and increasing CHA₂DS₂-VASc score with annualized risk of SSE were observed. Irrespective of device-detected AF duration, CHA₂DS₂-VASc 0-1 patients demonstrated low SSE rates. Overall, an interaction between AF duration and CHA₂DS₂-VASc score was evident, capable of allowing further risk stratification of AF patients for SSE and possibly of use in guiding anticoagulation treatment.