I. Challenges in the treatment of atrial fibrillation The prevalence of atrial fibrillation is about 1%, and the prevalence rate in the Chinese survey is 0.77%, according to which there are about 8 million patients with atrial fibrillation. The population with AF is expected to increase significantly in the future due to the ongoing epidemic of risk factors that contribute to AF, including an aging population, hypertension, obesity, heart failure, and diabetes. The most common complication of AF is thromboembolism, especially ischemic stroke. the prevalence of stroke in elderly AF patients over 80 years old is 30% higher. The first large prospective study in China conducted by Hu Dayi et al. suggested that warfarin (INR 2.0-3.0) was superior to aspirin in reducing the net clinical benefit of thromboembolic and bleeding complication endpoints, although the incidence of bleeding was higher in both. The results of this study confirm that adjusting the INR between 2 and 3 in patients taking warfarin is the optimal balance of efficacy and safety, and the same applies to the Chinese population. Despite the solid evidence from relevant studies both domestically and internationally, both Western and Chinese surveys have shown a significant gap between warfarin application and guidelines in patients with AF. The Chinese survey showed that only 9.8% of patients with atrial fibrillation with a CHADS score of 1 or higher used warfarin for anticoagulation, 53.5% used aspirin, and 37.0% did not use antithrombotic drugs. The limitations of the warfarin drug itself are one of the reasons for the current anticoagulation status of patients with atrial fibrillation, mainly including: the narrow window of safety and effectiveness of warfarin; the stability of INR is affected by many factors, and long-term monitoring of INR is burdensome for both patients and physicians. To improve long-term antithrombotic therapy in patients with atrial fibrillation, the indications for anticoagulation should be selected rationally and the use of warfarin should be standardized. The ACC/AHA guidelines recommend antithrombotic drugs for the prevention of thromboembolism in all patients with atrial fibrillation, except in isolated atrial fibrillation and in cases of contraindication. Antithrombotic agents are selected based on the absolute risk of stroke and bleeding, the relative risk to the patient, and the benefit. Anticoagulation for patients with atrial flutter is the same as for patients with atrial fibrillation. ACCP8 guidelines for antithrombotic therapy recommend that all patients with AF (paroxysmal AF) be given anticoagulation (INR 2.0-3.0) with one of the following: ischemic stroke, TIA, systemic embolism; if the patient has two or more intermediate risk factors (age >75 years, history of hypertension, diabetes mellitus, moderate to severe left ventricular systolic insufficiency and or heart failure). Patients with atrial fibrillation (paroxysmal atrial fibrillation) with one intermediate risk factor may be treated with either antiplatelet or anticoagulation, with anticoagulation preferred over antiplatelet. Patients with atrial fibrillation (paroxysmal atrial fibrillation) aged 75 years at risk of bleeding but without contraindications to oral anticoagulation; or other patients with intermediate risk factors but unable to tolerate standard intensity anticoagulation. Management of INR above the therapeutic range (American Thoracic Society 7th Meeting Guidelines) Clinical situations recommend INR above the therapeutic range but <5.0; dose reduction or suspension without significant bleeding and increased monitoring frequency; restarting therapy from a lower dose when INR drops to the therapeutic range. Dose reduction may not be necessary if INR is only slightly above the therapeutic range. INRs ≥5.0 but <9.0 without significant bleeding suspend next dose or both doses and increase monitoring frequency; restart treatment at a lower dose when INR falls into therapeutic range. OR: suspend one dose and give oral vitamin K1* (1-2.5 mg), especially if the patient is at increased risk of bleeding due to undergoing emergency surgery, preoperatively and INR needs to be reversed quickly: vitamin K1 (≤5 mg orally) may be applied with the expectation that INR will fall within 24 hours; if INR remains high, add vitamin K1 (1-2 mg orally) INRs >9.0, no Suspend warfarin therapy for obvious bleeding; and give vitamin K1 (5-10 mg orally) with the expectation that the INR will fall firmly within 24 to 48 hours. If needed, monitor more frequently and add vitamin K1. restart treatment from a lower dose when INRs fall into therapeutic range. Discontinue warfarin therapy for elevated INRs with severe bleeding; give vitamin K1 (10 mg slowly sedated), supplemented with fresh plasma, concentrated prothrombin complex, or recombinant factor VIIa, depending on the urgency of the condition. Discontinue warfarin for elevated INRs with life-threatening bleeding; give concentrated prothrombin complex or recombinant factor VIIa, along with supplementation with vitamin K1 ((10 mg slowly administered by IV). Repeat the above treatment as necessary, depending on the INR value. In patients with mild to moderate elevation of INR without severe bleeding, it is recommended to give oral vitamin K without subcutaneous (SC) administration. IV. Antithrombotic therapy in special cases 1. Treatment in the acute phase of ischemic stroke There are no studies on acute thrombolytic therapy in ischemic stroke associated with atrial fibrillation, and the results of meta-analysis show that atrial fibrillation is a risk factor for intracranial hemorrhage after thrombolysis. ACCP guidelines recommend that the absence of intracranial hemorrhage should be confirmed by CT or MRI scan and the extent of ischemia should be evaluated before applying any anticoagulant. In patients with atrial fibrillation with large infarct size, worsening clinical symptoms, unexplained headache, routine review of head CT, no intracranial hemorrhage and small infarct size, warfarin can be used and the INR maintained at 2-3 as long as the patient has normal blood pressure. intracranial hemorrhage is a contraindication to immediate and subsequent long-term warfarin use. Antithrombotic therapy during resuscitation is the most serious complication of resuscitation, which can occur during in vivo and in vitro electrical resuscitation, pharmacological resuscitation and spontaneous resuscitation. Thromboembolic events can occur up to 10 days after resuscitation, but most occur in the first 72 hours after resuscitation. Duration of atrial fibrillation longer than 48 hours or unknown: prophylactic application of adjusted doses of warfarin (INR2-3) before and 3-4 weeks after resuscitation, or TEE can be used to simplify resuscitation, but intravenous heparin and or warfarin anticoagulation is still required. Duration of atrial fibrillation less than 48 hours: It is common practice to directly resuscitate without TEE or prolonged anticoagulation prior to resuscitation. If not contraindicated, heparin anticoagulation (e.g., intravenous heparin target APTT60s or low molecular heparin) is given concurrently. Warfarin (INR 2.0-3.0) anticoagulation should be given for 4 weeks after resuscitation, regardless of the preresuscitation management. 3. Anticoagulation in patients with AF after PCI or revascularization undergoing coronary intervention, especially in high-risk AF patients with stent implantation, may require a combination of warfarin and antiplatelet agents, but there is no direct clinical research evidence. The guidelines suggest that warfarin, low-dose aspirin (less than 100 mg per day) and/or clopidogrel (75 mg per day) may be given concurrently at this time, but with an increased risk of bleeding. The course of clopidogrel is similar to that of the general patient, depending on the type of stent implanted. Thereafter, in the absence of coronary events, anticoagulation therapy can be applied alone. Care is needed to regulate the dose intensity of anticoagulation with an INR maintained at 2.0. 4. In other AF combined with acute myocardial infarction, UFH is given and APTT is adjusted if not contraindicated. atrial fibrillation combined with thyrotoxicosis, standard intensity anticoagulation INR 2.0-3.0 is given; after normal thyroid function, antithrombotic therapy is given according to risk stratification. In hypertrophic cardiomyopathy combined with atrial fibrillation, standard intensity anticoagulation INR 2.0-3.0. Except for patients with low risk of thrombosis, antithrombotic therapy is given during pregnancy according to the patient’s risk stratification. warfarin is prohibited in early pregnancy (can lead to embryopathy), and heparin can be applied throughout the pregnancy instead. V. Other antithrombotic treatments and new anticoagulants New anticoagulants and interventions are under development and clinical evaluation, and small studies have shown that left-ear blocking devices and filters can be used in high-risk patients who cannot tolerate anticoagulant therapy, but there are complications. The most active area of research is novel anticoagulants, primarily targeting factor Xa and factor IIa. Compared to warfarin, the new anticoagulants are comparable in efficacy but are easy to use, do not require dose adjustment, and do not require routine monitoring. Rivaroxaban and dapigatran are in phase 3 clinical studies. VI. Summary: Atrial fibrillation is an important risk factor for stroke, and the use of anticoagulant drugs in Chinese patients with atrial fibrillation is very unsatisfactory. To fundamentally improve the prevention of thromboembolism in patients with atrial fibrillation, reasonable antithrombotic therapy should be selected according to the risk stratification of patients with atrial fibrillation, and attention should be paid to the thrombosis/hemorrhage balance. Studies have confirmed that monitored adjusted doses of warfarin (INR 2.0-3.0) are equally safe and effective in Chinese patients with intermediate to high-risk AF. Certain special circumstances, such as pregnancy and resuscitation, require special antithrombotic therapy. Improve the management of long-term anticoagulation therapy, such as specialized anticoagulation clinics and instant INR testing devices. New anticoagulants may be the future direction of anticoagulation, easy and without monitoring.