Atrial Fibrillation Burden: Assessment, Clinical Significance, and Therapeutic Implications.

Atrial fibrillation (AF) is traditionally classified using categorical clinical patterns and binary recurrence endpoints. However, these measures do not fully reflect arrhythmia frequency, duration, temporal distribution, or progression. AF burden, defined as the proportion of monitored time spent in AF, provides a more granular measure of disease activity and therapeutic response. Recent advances in cardiac implantable electronic devices, insertable cardiac monitors, wearable technologies, and digital platforms have significantly improved burden assessment, although considerable heterogeneity remains in monitoring methods, definitions, and clinically relevant thresholds. This review examines contemporary approaches to AF burden measurement and its associations with thromboembolic risk, heart failure, hospitalization, symptoms, quality of life, disease progression, and mortality. We particularly discuss the reduction of AF burden as a potential therapeutic target following antiarrhythmic drug therapy and catheter ablation, and the limitations of conventional recurrence definitions based on episodes lasting more than 30 s. This review also focuses on the implications for rhythm-control selection, post-ablation monitoring, anticoagulation, and clinical-trial design, while proposing priorities for standardized burden-based assessment.