Atrial fibrillation is the most common arrhythmia, with an increasing incidence and prevalence, significantly increasing the risk of death, stroke, heart failure, cognitive impairment, and dementia, severely impacting the quality of life for patients and burdening society and healthcare systems. In recent years, exercise-based cardiac rehabilitation has gradually become a new approach for the treatment of patients with heart disease. The main research topics include: 1. Changes in atrial fibrillation burden in non-permanent atrial fibrillation patients after 12 weeks of HIIT(high-intensity interval training ) or MIIT (moderate-intensity interval training). 2. Changes in cardiorespiratory fitness, quality of life scores, mental health assessment scores, atrial strain, and left ventricular diastolic function in non-permanent atrial fibrillation patients after 12 weeks of aerobic interval training, along with follow-up on the occurrence of exercise-related adverse events and adverse cardiovascular events during the study period.

This study is a multicenter, prospective, randomized clinical trial. It aims to enroll a total of 156 patients with non-permanent atrial fibrillation. Participants will be randomly assigned to the HIIT group, MIIT group, and control group. The HIIT and MIIT groups will receive 12 weeks of high-intensity interval aerobic exercise training and moderate-intensity interval aerobic exercise training, respectively, while the control group will maintain their previous exercise habits.The study will compare the atrial fibrillation burden, cardiorespiratory fitness, quality of life scores, mental health scale scores, blood lipids, blood glucose levels, atrial strain, and ventricular diastolic function changes among patients in the different exercise intervention groups and the control group after 12 weeks. Additionally, the occurrence rates of exercise-related adverse events and cardiovascular adverse events during the follow-up period will be assessed to evaluate the effectiveness and safety of cardiac rehabilitation in the treatment of atrial fibrillation patients.

Inclusion Criteria:

1. Age range: 18-74 years;
2. Patients with non-permanent atrial fibrillation;
3. Resting heart rate ≤110 beats/min;
4. No history of receiving a formal exercise prescription within the past six months;
5. Willing to participate in this study, provide written informed consent, and agree to comply with follow-up procedures.

Exclusion Criteria:

1. History of myocardial infarction, endocarditis/myocarditis/pericarditis, stroke (ischemic/hemorrhagic), pulmonary embolism, lower extremity venous thrombosis, or cardiac surgery within the past 6 months;

2. Moderate to severe pulmonary arterial hypertension, moderate to severe valvular heart disease, hypertrophic cardiomyopathy, aortic stenosis/dilation/dissection/intramural hematoma, congenital heart disease;

3. Heart failure (NYHA class III-IV) or acute exacerbation of heart failure within the past 3 months;

4. Unstable angina or severe coronary artery disease without revascularization;

5. Concurrent severe arrhythmias

   • frequent multifocal premature ventricular contractions
   • ventricular tachycardia, ventricular fibrillation
   • high-degree or complete atrioventricular block
   • ventricular asystole lasting more than 5 seconds

6. Uncontrolled hypertension or hypotension;

7. Severe renal or hepatic dysfunction

   • Stage 5 chronic kidney disease, defined as glomerular filtration rate <15 ml/(min•1.73 m2) or requiring dialysis;
   • Patient with alanine aminotransferase (ALT) or aspartate aminotransferase (AST) levels greater than or equal to 5 times the upper limit of normal as defined by the center during screening;

8. Hypoxemia or severe lung disease;

9. Lower extremity arterial stenosis or musculoskeletal disease preventing exercise training;

10. Intracardiac thrombus;

11. Pregnancy;

12. Cognitive impairment preventing study cooperation;

13. Severe anemia, infection, electrolyte disturbances, hyperthyroidism;

14. Planned atrial fibrillation ablation during the study period;

15. Post-implantation of pacemaker or ICD;

16. Inability to use smart devices;

17. Concurrent cancer or autoimmune or systemic inflammatory disease;

18. Regular moderate-to-high intensity exercise habits (≥2 sessions of high-intensity endurance training per week or ≥3 sessions of moderate-intensity endurance training