Acute atrial fibrillation attack refers to the first attack of atrial fibrillation, the episode of paroxysmal atrial fibrillation, and the rapid ventricular rate and/or worsening of persistent or permanent atrial fibrillation. The rate is too rapid and irregular, and the symptoms suddenly and significantly worsen, requiring urgent intervention.
Strategies and procedures for emergency management of atrial fibrillation
Acute atrial fibrillation is firstly divided into two categories, hemodynamically unstable and hemodynamically stable, according to whether the vital signs are stable. Hemodynamically unstable atrial fibrillation should be terminated as soon as possible and converted to sinus rhythm; hemodynamically stable atrial fibrillation should be based on the duration of atrial fibrillation onset, the severity of symptoms, the risk of stroke, and the underlying heart disease. Different treatment strategies are adopted to relieve symptoms, improve prognosis, and reduce the occurrence of cardiovascular events. 
Figure 1 Flow chart of emergency atrial fibrillation cardioversionHemodynamically unstable acute atrial fibrillation
Definition of hemodynamically unstable atrial fibrillation:①Contraction pressure <90 mmHg, and the manifestations of hypoperfusion, such as restlessness, restlessness, dullness, clammy skin, decreased urine output (<20 ml/h), etc.;②pulmonary edema;< span>③ Myocardial ischemia (chest pain and/or electrocardiographic manifestations of acute ischemia).
For hemodynamically unstable atrial fibrillation, the primary task is to restore sinus rhythm. If there are no contraindications, synchronous direct current cardioversion should be given immediately (I, B). For atrial fibrillation complicated with pre-excitation syndrome, if the ventricular rate is >200 beats/min, emergency synchronized cardioversion is recommended; if the ventricular rate reaches 250 beats/min, immediate synchronized cardioversion is recommended. Therapeutic amount of unfractionated heparin or low molecular weight heparin should be given for anticoagulation immediately before electrical cardioversion; If it is too late for anticoagulation, unfractionated heparin or low molecular weight heparin should be administered immediately after cardioversion (I, C). Except for low-risk stroke patients with atrial fibrillation duration < 24 hours, oral anticoagulant therapy should be continued for 4 weeks after electrical cardioversion, preferably NOAC; and then whether long-term oral anticoagulation therapy is required based on CHA₂DS₂-VASc risk assessment ( I, A). Persistent atrial fibrillation or unsuccessful electrical cardioversion can be given drugs to convert atrial fibrillation and then cardioverted again . Hemodynamically stable acute atrial fibrillation
For hemodynamically stable acute atrial fibrillation, the risk of thromboembolism should be evaluated first, and the time to start anticoagulation and whether long-term anticoagulation should be determined; And whether there is organic heart disease, decide whether to control the ventricular rate; finally decide whether to cardiovert, the time and method of cardioversion, and the prevention of atrial fibrillation recurrence after cardioversion. for paroxysmal AF/onset duration ≥ 48 hours, or patients with unclear duration of atrial fibrillation/flutter, cardioversion after 3 weeks of effective anticoagulation therapy (I, B); or after anticoagulation therapy and TEE examination to exclude atrial thrombus. Law (I, B). Routine anticoagulation was given for 4 weeks after cardioversion, and long-term anticoagulation was determined according to the CHA₂DS₂-VASc score. For patients with acute atrial fibrillation at high risk of stroke, if the duration of atrial fibrillation is ≥12 hours, anticoagulation is required for 3 weeks Reconversion of atrial fibrillation requires long-term anticoagulation after conversion. For patients with acute atrial fibrillation at low and intermediate risk of stroke, if the duration of the atrial fibrillation attack is ≥24 hours, anticoagulation therapy should be initiated, and follow-up cardioversion of atrial fibrillation should be performed. Preparation, anticoagulation should be continued for 4 weeks after cardioversion of atrial fibrillation. For patients at intermediate risk of stroke, continuation of long-term anticoagulation therapy will be considered. For patients with low risk of stroke, the duration of atrial fibrillation is <24 hours, and anticoagulation may not be required after cardioversion of atrial fibrillation treat. OAC is preferably NOAC (I, A), and low molecular weight heparin combined with oral warfarin can also be used. Gradually transition to oral warfarin anticoagulation alone. 2. Ventricular rate controlif atrial fibrillation with tachycardia and symptoms Obviously, ventricular rate control and symptom relief should be done first, and then other treatment strategies and timing should be considered (I, B). At present, it is recommended to choose loose ventricular rate control, that is, the target value of the resting ventricular rate is ≤100 beats/min or the ventricular rate when walking is ≤110 beats/min. If the symptoms are not relieved, strict ventricular rate control, that is, resting Ventricular rate <80 beats/min. In terms of drug selection, intravenous beta-blockers (metoprolol, smolol, etc.), non-dihydropyridine calcium channel blockers (verapamil, diltiazem, etc.); patients with chronic heart failure can choose a combination of low-dose beta-blockers or digitalis preparations ( anthocyanin C, etc.). 
Intravenous preparations are mainly used in the acute attack of atrial fibrillation, with fast onset and positive effect. Once the ventricular rate is controlled, oral preparations should be used promptly to prevent repeated episodes of rapid ventricular rate. Ventricular rate control does not improve long-term cardiac remodeling. After ventricular rate control in acute atrial fibrillation, cardioversion and maintenance of sinus rhythm can be considered according to the condition and the patient’s wishes, or continuous oral medication can be used to control the ventricular rate. Beta-blockers, calcium channel blockers, and digitalis should not be used in patients with atrial fibrillation and preexcitation syndrome Class of drugs to control ventricular rate, in recent years, amiodarone has not been recommended. In such patients, electrical cardioversion should be considered as soon as possible. rhythm control improves symptoms, and early rhythm control may improve prognosis (I, B). (1) Indications for cardioversionPatients with severe symptoms at the onset of atrial fibrillation, with significant heart failure, angina pectoris, long-term contraindications to anticoagulation, or unsatisfactory ventricular rate control, should choose rehab rhythm and maintenance of sinus rhythm; for newly onset atrial fibrillation, young patients, and patients with still obvious symptoms after ventricular rate control, cardioversion therapy may be considered; cardioversion therapy should be preferred for preexcitation syndrome or pregnancy complicated with atrial fibrillation; paroxysmal Cardioversion therapy can be considered for patients with atrial fibrillation with onset time < 48 hours and atrial fibrillation diagnosis < 1 year with cardiovascular risk according to the condition and the patient's wishes. (2) The best time for cardioversion span>Considering the risk of thrombosis, clinically, the duration of atrial fibrillation episode <48 h is often used as the time node for immediate cardioversion. Because atrial fibrillation lasts ≥48 hours, there is a possibility of thrombosis in the atrium, and cardioversion must be performed after 3 weeks of effective anticoagulation therapy or after exclusion of atrial thrombosis by TEE examination. The onset time of atrial fibrillation is less than 12 hours, and the ventricular rate should be controlled first to relieve symptoms; the onset time of atrial fibrillation in high-risk stroke patients ≥ 12 hours, and the onset time of atrial fibrillation is ≥ 24 hours in patients with intermediate and low risk of stroke, and anticoagulation therapy should be started to prepare for the subsequent cardioversion of atrial fibrillation or prolong the time window of cardioversion (≥48 hours). “Wait and see” strategy (atrial fibrillation may be self-converted within 24 hours); if atrial fibrillation lasts ≥24 hours, atrial fibrillation cardioversion can be initiated, because atrial fibrillation drug cardioversion takes a certain amount of time to take effect. In summary, for acute atrial fibrillation or newly developed atrial fibrillation, the best time for cardioversion may be 24~ 48 h is relatively more suitable. (3) Cardioversion< /section>Electrical cardioversion terminates atrial fibrillation quickly and with a high success rate. In the emergency room, the success rate of electrical cardioversion is about 90%, and the success rate of drug cardioversion is 50% to 60%. ①Electrical cardioversionElectrical cardioversion can be used in patients with paroxysmal atrial fibrillation with poor ventricular rate control or significant symptoms. In patients with severe angina pectoris, myocardial infarction, and heart failure, electrical cardioversion should be synchronized immediately. Contraindications to electrical cardioversion are digitalis intoxication and severe hypokalemia. Addition of AAD before electrical cardioversion can improve the success rate of cardioversion, such as amiodarone, propafenone, Ibrahimovic Little,Sotalol, Flecainide, etc. In addition, ventricular rate-controlling drugs such as beta-blockers, diltiazem, or verapamil may also be administered before electrical cardioversion. Medical cardioversion is more effective for atrial fibrillation within 7 days of onset. Commonly used drugs are class Ic drug propafenone, class III drugs dofetilide and ibutilide. After cardioversion of acute atrial fibrillation, timely transition to oral drugs to maintain sinus rhythm according to the situation can prevent or reduce the recurrence of atrial fibrillation. 
Document Index: Chinese Medical Association Cardiac Electrophysiology and Pacing Branch, Chinese Medical Doctor Association Cardiology Professional Committee, Chinese Atrial Fibrillation Center Alliance Atrial Expert Working Committee on Prevention and Treatment of Fibrillation. Atrial Fibrillation: Current Understanding and Treatment Recommendations (2021). Chinese Journal of Arrhythmia, 2022, 26(1): 15-88.