Inclusion Criteria:  1. Clinical diagnosis of no history of atrial fibrillation/flutter; 2. Heart rate ≥50 beats/min; 3. EF > 40%; 4. No history of emergency cardiac surgery in our hospital; 5. Participate voluntarily and sign the informed consent, and can accept the follow-up of more than 2 years.  Exclusion Criteria:  1. Atrial fibrillation/flutter; 2. Left atrial diameter >5.5cm; 3. Previous cardiac surgery or emergency surgery (<12h); 4. Sick sinus node syndrome; 5. Ventricular preexcitation or preexcitation syndrome; 6. Second degree or above atrioventricular block; 7.Myocardial infarction occurred within 7 days; 8. Infection, sepsis, rheumatic or inflammatory diseases; 9. Abnormal liver and kidney function (three times higher than the upper limit of normal); 10. Uncontrolled hyperthyroidism, severe obstructive sleep apnea, and acute alcoholism; 11. Any ischemic events (stroke or TIA) that occurred 180 days before the participant signed the informed consent, or any known unresolved complications from previous stroke/TIA;Thrombosis; 12. Patients with other diseases requiring radiotherapy, chemotherapy and long-term hormone therapy; 13. Patients' life expectancy makes it unlikely that follow-up will be completed; 14. Participate in, or are expected to participate in, other clinical trials of any drugs, devices or biologics during the study period; 15. Patients with contraindications to dynamic electrocardiogram; 16. Patients who are unwilling or unable to fully comply with study procedures and follow-up.