Why are patients with atrial fibrillation most afraid of blood clots? Atrial fibrillation is the most common persistent arrhythmia in clinical practice. The incidence of atrial fibrillation in the general population is 0.5%-1.3%, and its incidence gradually increases with age, reaching more than 10% in people over 80 years old. The main risk of atrial fibrillation is the formation of blood clots in the heart, which can lead to complications such as stroke, organ embolism and peripheral vascular embolism after dislodging. Among them, stroke is the most common and dangerous complication of atrial fibrillation. Follow-up studies of patients with atrial fibrillation have shown that the incidence of stroke at 5 years is as high as 20%. The mortality rate one year after stroke is 30%. The risk of stroke due to AF increases with age, from 1.5%/year for AF patients aged 50-59 years to 23.5%/year for AF patients aged 80-89 years. The clinical characteristics of stroke in patients with atrial fibrillation are the rapid onset of the stroke (causing significant symptoms within tens of minutes) and the severity of the stroke (death and disability rate of more than 50%). In conclusion, atrial fibrillation causes stroke with four characteristics: “high age”, “high incidence”, “high recurrence”, and “high mortality and disability”. The four characteristics are “high age”, “high incidence”, “high recurrence”, and “high mortality and disability”. Therefore, the goal of atrial fibrillation is to prevent strokes. Previously, the treatment focused on the application of pharmacological anticoagulation or the restoration and maintenance of sinus rhythm by radiofrequency ablation. What are the shortcomings of pharmacologic anticoagulation and radiofrequency ablation for stroke prevention? Pharmacological prevention of stroke in atrial fibrillation relies primarily on oral warfarin. However, there are many problems with long-term oral warfarin: while warfarin prevents blood clots, its anticoagulant effect can cause bleeding complications, the drug’s effect is affected by many foods and drugs, and frequent hospital visits are required to monitor coagulation to prevent drug overdose. Therefore, taking warfarin causes inconvenience to patients. Especially in older patients, who are at high risk of bleeding themselves and often cannot do regular hospital laboratory tests, warfarin therapy is poorly tolerated and adhered to in elderly patients. However, these patients are precisely those who are at high risk of stroke. And some new anticoagulants are expensive, their efficacy is not perfect, and bleeding complications are still unavoidable. In the last decade or so, radiofrequency ablation therapy for atrial fibrillation has been widely accepted. However, the success rate of this treatment is not high (about 80% for paroxysmal AF and less than 50% for chronic, permanent AF), some patients need repeated multiple RF ablations, and some still need anticoagulation after the procedure. Moreover, radiofrequency ablation is an invasive treatment with high costs and long operation times. What is the left auricle? The left heart ear is an ear-shaped sac that protrudes from the left atrium and is part of the left atrium, a legacy of human evolution. During embryonic development, the primitive left atrium becomes the left auricle, and the primitive right and left pulmonary veins are incorporated into the left atrium, which becomes the main component of the left atrium. Is the left auricle the “old nest” of thrombus formation? Clinical studies have shown that in patients with atrial fibrillation, more than 90% of thrombus formation is related to the left auricle. In normal sinus rhythm, the left ear rarely forms thrombus because of its normal contraction capacity. In atrial fibrillation, the left auricle is significantly enlarged and loses its effective regular contraction, resulting in blood pooling in the left auricle and making it highly susceptible to thrombus formation. What are the chances of thrombosis due to different shapes of the left heart ear? People have a thousand faces, and the left heart ear also has different shapes, including chicken wings, weathervane, cactus and cauliflower. Clinical studies have shown that structures with more depressions in the inner cavity of the heart ear and deeper crypt may be prone to thrombus formation. Therefore, the incidence of concurrent strokes is relatively high in the cauliflower-shaped left heart ear, and in the chicken-wing shape, the incidence of strokes is lower. Analysis of the morphologic structure of the left heart ear may be an important factor in the risk stratification of stroke complicated by atrial fibrillation and may be the main basis for future decisions on left ear occlusion. How is left-ear occlusion performed? Transcatheter occlusion or surgical treatment of the left heart ear has received a lot of attention in recent years as a means of preventing stroke and thromboembolism in patients with atrial fibrillation. Transcatheter occlusion of the left ear is considered more promising because of its small wound size, lack of chest opening and extracorporeal circulation. The procedure is similar to stenting, in which the surgeon percutaneously punctures the patient’s femoral vein, establishes access, and then delivers a compressed blocker along the femoral vein to the opening of the left auricle, where the blocker is opened to isolate the inner chamber of the left atrium from the left auricle. Which patients with atrial fibrillation are candidates for left-ear occlusion? Currently, the main indications for transcatheter left auricular occlusion are patients who are at high risk of bleeding, who are intolerant of warfarin anticoagulation, or who do not want warfarin anticoagulation. As technology improves and experience is gained, the indications may be further broadened and it is expected to become a routine treatment for stroke prevention in patients with atrial fibrillation. Clinical studies have shown that after left-ear blockade, patients have a low chance of recurrent stroke and do not require pharmacological anticoagulation. What does the blocker look like? Zhongshan Hospital uses the WATCHMAN Left Ear Blocking System, which is the most intensively researched and the only one in China with long-term clinical trial data and follow-up data that has been approved for marketing. It is shaped like a hemispherical straw hat with several fixed stents in the recess. Long-term data from relevant trials show that the blocking system is more effective than warfarin in preventing strokes, reducing death and disability rates, and reducing the occurrence of bleeding, and is more effective (more effective than anticoagulants) in patients who have already had a stroke (secondary prevention).