Cardiac CT Evaluation of EAT in AF vs. Non-AF Subjects

The goal of this cross-sectional study is to explore the relationship between atrial structural characteristics (such as epicardial adipose tissue infiltration and atrial size) and atrial fibrillation (AF), as well as the differences in these characteristics among different AF subtypes. It will also clarify the independent association between pericardial fat distribution and AF (and its subtypes) after excluding confounding factors. The main questions it aims to answer are: * What are the differences in epicardial adipose tissue volume and atrial size among patients with sinus rhythm, paroxysmal AF, and persistent AF? * Is pericardial fat distribution independently associated with AF and its subtypes after adjusting for confounding factors such as age, hypertension, and left atrial enlargement? Researchers will enroll patients who undergo coronary CTA or left atrial CTA at The Second Affiliated Hospital of Zhejiang University School of Medicine, and match and divide them into three groups (sinus rhythm group, paroxysmal AF group, and persistent AF group) based on BMI and other factors. They will compare the differences in pericardial fat distribution and baseline characteristics among the three groups and analyze the independent association between pericardial fat and AF. Participants will: * Provide relevant clinical baseline data and CTA examination results * Complete the collection of demographic information, medical history, and laboratory test data The study duration is 6 months, starting from the date of ethical approval, with an expected end date of June 2026. A total of 600-900 participants (200-300 per group) will be enrolled to ensure the reliability and clinical applicability of the research conclusions.