1.Overview
Atrial fibrillation, referred to as atrial fibrillation, is the most common persistent arrhythmia. The overall incidence of atrial fibrillation is 0.4%, and the incidence of atrial fibrillation increases with age, up to 10% in people over 75 years of age. The frequency of atrial excitation in atrial fibrillation is 300-600 beats/min, and the heart rate is often fast and irregular, sometimes reaching 100-160 beats/min, which is not only much faster than the normal heart rate, but also absolutely irregular, and the atria lose their effective contraction function.
Large-scale research studies in China have shown that the prevalence of atrial fibrillation is 0.77%, and the prevalence of atrial fibrillation is higher in men (0.9%) than in women (0.7%), and the prevalence of atrial fibrillation over 80 years of age is 7.5%. In addition, the increase in the prevalence of atrial fibrillation will be closely related to the increase in coronary heart disease, hypertension and heart failure, and atrial fibrillation will become one of the most prevalent cardiovascular diseases in the next 50 years.
2. Etiology and classification
Common causes of atrial fibrillation include hypertension, coronary artery disease, cardiac surgery, valvular disease, chronic lung disease, heart failure, cardiomyopathy, congenital heart disease, pulmonary embolism, hyperthyroidism, pericarditis, etc. It is associated with alcohol consumption, mental stress, water-electrolyte or metabolic imbalance, and severe infection; in addition, it can be combined with other types of arrhythmias.
There is no uniform definition of atrial fibrillation, but it can be divided into paroxysmal atrial fibrillation, persistent atrial fibrillation and permanent atrial fibrillation according to the duration; usually, paroxysmal atrial fibrillation refers to those who can return to sinus rhythm on their own within 7 days, usually for less than 48 hours; persistent atrial fibrillation refers to those who last for more than 7 days and require drugs or electric shock to return to sinus rhythm; permanent atrial fibrillation refers to those who cannot return to sinus rhythm or recur within 24 hours after the return. Permanent atrial fibrillation refers to those who cannot be converted to sinus rhythm or recur within 24 hours after conversion.
According to the presence or absence of underlying heart disease, atrial fibrillation is divided into pathological atrial fibrillation (atrial fibrillation accompanied by other underlying heart disease) and idiopathic atrial fibrillation (no underlying heart disease in clinical examination), idiopathic atrial fibrillation often occurs in younger people, mostly younger than 50 years old, idiopathic atrial fibrillation is sometimes called isolated atrial fibrillation, accounting for about 6%-15% of patients with atrial fibrillation.
3.Symptoms and hazards
The common clinical symptoms of atrial fibrillation include.
(1) Palpitations: feeling a disturbed or accelerated heartbeat, physical fatigue or exertion.
(2) Dizziness: dizziness or fainting.
(3) Chest discomfort: pain, pressure, or discomfort.
(4) Shortness of breath: difficulty breathing during mild physical activity or at rest; in addition, some patients may have no symptoms at all.
In atrial fibrillation, the atria lose their contractile function, and blood is easily stagnated in the atria and forms thrombi, which can be dislodged and travel throughout the body, leading to cerebral embolism (stroke), arterial embolism of the limbs (even amputation in severe cases), etc. Risk factors for stroke in patients with atrial fibrillation include previous history of embolism, hypertension, diabetes, coronary artery disease, heart failure, left atrial enlargement, and age over 65 years. Loss of atrial systolic function and prolonged increase in heart rate in atrial fibrillation can lead to heart failure and increase mortality (twice the normal rate).
4.Auxiliary examination and diagnosis
Initial diagnosis of atrial fibrillation can be made based on clinical symptoms and signs, but confirming the diagnosis requires electrocardiography, which is simple and easy to perform; however, for patients with transient episodes of atrial fibrillation that are difficult to pounce on, tests such as ambulatory electrocardiography are required.
5.Treatment
The objectives of atrial fibrillation treatment include
(1) Restoration of sinus rhythm: it is the best outcome of atrial fibrillation treatment. Only when sinus rhythm (normal heart rhythm) is restored can atrial fibrillation be fully treated; therefore, treatment to restore sinus rhythm should be attempted for any patient with atrial fibrillation.
(2) Control of rapid ventricular rate: For patients with atrial fibrillation who cannot regain sinus rhythm, medications can be used to slow down the faster ventricular rate.
(3) Prevention of thrombosis and stroke: If sinus rhythm cannot be restored in atrial fibrillation, anticoagulant drugs can be applied to prevent thrombosis and stroke.
For certain diseases such as hyperthyroidism, acute alcoholism, and drug-induced atrial fibrillation, atrial fibrillation may disappear on its own or may persist after the cause is removed.
Medications remain an important treatment for AF, restoring and maintaining sinus rhythm, controlling the ventricular rate, and preventing thromboembolic complications.
Drugs to restore sinus rhythm (normal rhythm): For new-onset atrial fibrillation, because of its high rate of spontaneous sinus resumption within 48 hours (about 60% within 24 hours), observation can be started, or propafenone (450 mg to 600 mg) or flecainide (300 mg) can be administered in a single dose.
For those whose atrial fibrillation has lasted for more than 48 hours but less than 7 days, intravenous medications can be used to transcend the rhythm, such as flecainide, dofetilide, propafenone, ibuprofen and amiodarone, with a success rate of up to 50%. For AF episodes lasting longer than a week (persistent AF), the effectiveness of pharmacological cardioversion is greatly reduced, and commonly used and proven effective drugs include amiodarone, Ibutilide, and dofetilide.
Drugs to control the ventricular rate (frequency control): Controlling the ventricular rate can ensure the basic function of the heart and minimize the cardiac dysfunction caused by atrial fibrillation.
Commonly used drugs include.
(1) β-blockers.
The most effective, most commonly used and often applied alone drugs.
(2) Calcium channel antagonists.
(2) calcium channel antagonists: such as verapamil and diltiazem can also be used effectively for ventricular rate control in atrial fibrillation, especially for the control of ventricular rate in exercise than digoxin, and the effect of the combination with digoxin is also better than alone. It is especially used in patients without organic heart disease or normal left ventricular systolic function and with chronic obstructive pulmonary disease.
(3) Digitalis.
It has been considered as the first-line drug to control the ventricular rate of atrial fibrillation in emergency situations, and is currently used clinically for ventricular rate control in the presence of left heart failure.
(4) Amiodarone.
It is not recommended for long-term ventricular rate control in chronic atrial fibrillation, but amiodarone is preferred in combination with digitalis when other drugs are ineffective or contraindicated, or when atrial fibrillation combined with heart failure requires urgent ventricular rate control.
Non-pharmacologic treatments for AF include electrical cardioversion (conversion of sinus rhythm), radiofrequency ablation, and surgical labyrinthine procedures (complete cure of AF). Electrical cardioversion is a method of restoring sinus rhythm by using two electrode pads placed in the appropriate part of the patient’s chest and distributing an electric current through a defibrillator.
EPR is indicated for: emergency atrial fibrillation (e.g., myocardial infarction, extremely fast heart rate, hypotension, angina pectoris, heart failure, etc.), atrial fibrillation with severe symptoms that are difficult for the patient to tolerate, atrial fibrillation that was successfully resuscitated last time and has recurred without being maintained with medication. Electrical resuscitation is not a cure for atrial fibrillation, and patients often have recurrences of atrial fibrillation, and some patients will need to continue taking antiarrhythmic drugs to maintain sinus rhythm.
Catheter ablation is suitable for most patients with atrial fibrillation and is less invasive and easier for patients to undergo. Surgical labyrinth surgery is currently used in patients with AF who require cardiac surgery for other cardiac conditions.
Anticoagulation is necessary to prevent thrombosis and embolism in patients with atrial fibrillation. Anticoagulation with warfarin can reduce the risk of stroke by 68%; however, anticoagulation does not eliminate atrial fibrillation and cannot improve clinical symptoms such as palpitations, weakness, and heart failure. Patients with atrial fibrillation should be treated with anticoagulation if they are ≥65 years old; have a previous history of stroke or transient ischemic attack; congestive heart failure; hypertension; diabetes mellitus; coronary artery disease; left atrial enlargement; or left atrial thrombus on echocardiography.
Anticoagulation therapy must be guided by a specialist. Excessive anticoagulation may lead to bleeding, while insufficient anticoagulation strength has no preventive effect. Long-term application of warfarin requires testing of the national standard ratio (INR), especially at the beginning of the drug, which requires repeated blood tests and cannot be maintained by many patients for a long time. The effects of warfarin are easily influenced by other drugs or diet, making dose adjustments difficult to control. For some patients who cannot tolerate warfarin can be treated with aspirin or/and clopidogrel.
6. Prognosis
Stroke is one of the greatest hazards of atrial fibrillation, the incidence of stroke in patients with non-valvular atrial fibrillation is 5.6 times higher than normal, and the incidence of stroke in valvular atrial fibrillation is 17.6 times higher than normal; and the consequences of stroke caused by atrial fibrillation are more serious, with a disability rate of about 25% and a mortality rate of up to 25%.
7.Prevention
Some patients may need to avoid caffeine-containing substances such as tea, coffee, cola, and some over-the-counter medications, and be cautious with certain cough or cold medications, which may contain stimulants that may promote irregular heart rhythms, and ask your doctor or read the instructions before taking them to see if they are Before taking them, you should ask your doctor or read the instructions to see if they are suitable for you.
8. Common misconceptions
Patients with atrial fibrillation often have some misconceptions (misconceptions).
(1) Atrial fibrillation does not have any symptoms and does not require treatment. (1) Atrial fibrillation is asymptomatic and does not require treatment. The risk of atrial fibrillation and the need for treatment do not depend on the severity of the patient’s symptoms. Patients with atrial fibrillation should be systematically examined to assess the risk of atrial fibrillation and receive timely treatment regardless of the presence or absence of symptoms.
(2) Infrequent episodes of atrial fibrillation are not currently treated urgently. Patients with paroxysmal atrial fibrillation will have more episodes year by year, the duration of episodes will be prolonged, and there is no tendency for self-healing. Radiofrequency ablation surgery is most effective in early paroxysmal atrial fibrillation when structural changes in the atria are not present, so it is believed that patients with atrial fibrillation should receive treatment early.
(3) Loss of confidence due to recurrent episodes of atrial fibrillation even with drug therapy. Drugs have long been the main treatment method for atrial fibrillation, and even if they are taken daily, atrial fibrillation will recur in most patients. At present, with the continuous improvement of 3D navigation system and the rapid progress of radiofrequency ablation technology, the cure rate of atrial fibrillation has increased substantially, and the recurrence rate is decreasing day by day. The success rate of paroxysmal atrial fibrillation is high and the recurrence rate is low; the current success rate of chronic atrial fibrillation is low and the recurrence rate is high, but with the continuous progress of technology the recurrence rate is gradually decreasing.
(4) Atrial fibrillation is equivalent to coronary artery disease. Sometimes atrial fibrillation can coexist with coronary heart disease, most patients with atrial fibrillation and coronary heart disease are not necessarily related, and patients with coronary artery angiography and other series of tests to exclude coronary heart disease, atrial fibrillation is sometimes very serious; however, do not simply assume that atrial fibrillation is coronary heart disease because of the similarity of the two symptoms, and should receive regular atrial fibrillation treatment after a comprehensive systemic cardiac examination with a target.