This prospective multi-cohort observational study evaluates the association between peripheral blood lipidomic and ceramide profiles and atrial fibrillation. The study hypothesis is that peripheral blood lipidomic features and ceramide-related profiles are associated with the presence of atrial fibrillation. Participants with atrial fibrillation and control participants with other cardiovascular diseases will be prospectively enrolled. Peripheral blood samples will be analyzed using untargeted lipidomic profiling in one cohort and targeted ceramide assays in another cohort.