atrial fibrillation, plasma complement C1q, myocardial fibrosis, complex fractionated atrial electrograms, pulmonary vein isolation, Diseases of the circulatory (Cardiovascular) system, RC666-701

Background and objectiveThe complement system plays a crucial role in the pathogenesis and progression of cardiovascular diseases. C1q, a key initiator of the classical pathway, is closely associated with various chronic inflammatory conditions. This observational study aims to elucidate the potential risk relationship between serum complement C1q levels and atrial fibrillation (AF).Materials and methodsThis retrospective cohort study included 812 AF patients treated at the Affiliated Hospital of Qingdao University from January 2020 to October 2022, comprising 694 patients in the paroxysmal AF group and 118 in the persistent AF group. Serum complement C1q levels were measured using an enzyme-linked immunosorbent assay (ELISA).ResultsSerum C1q levels in the AF group were significantly lower than those in the control group (P