365medical.com: Hello, Professor Zhang, thank you for the interview! It is understood that atrial fibrillation is one of the most common heart rate arrhythmias in clinical practice. Can you please briefly discuss the incidence and hazards of atrial fibrillation, the main treatment methods and the progress of treatment strategies? Prof. Fengxiang Zhang: Atrial fibrillation, referred to as atrial fibrillation, is one of the most common clinical arrhythmias. Atrial fibrillation can be asymptomatic, can have panic, chest tightness, some patients have very severe symptoms, can appear angina pectoris, syncope, etc.; there are some patients with very special symptoms, once atrial fibrillation occurs, they have to relieve urination. Atrial fibrillation incidence in Europe and the United States more surveys, China’s existing surveys show that the incidence of atrial fibrillation is about 0.77%, so the calculation, China has atrial fibrillation patients is about 10 million, which is a relatively conservative estimate, because the incidence of atrial fibrillation increases with age, more than 10 million patients with atrial fibrillation is a huge team of patients! Atrial fibrillation has three major hazards: The first major hazard is embolism. When the normal sinus heart rate, the heartbeat is regular, but after atrial fibrillation heartbeat is chaotic, the contraction of the atria from order to disorder, so it is particularly easy to send embolism, embolism from where it comes? The left heart ear! Once the embolus falls from the left heart ear, it is especially easy to have cerebral embolism, which is commonly known as stroke; some patients have mesenteric artery embolism, the patient suddenly has stomach pain and comes to the clinic, and the abdominal enhancement CT (CTA) examination reveals that there is an embolus in the mesenteric artery, and then the ECG will reveal that it is atrial fibrillation; other patients show renal artery embolism, and they have renal colic, and after the clinic finds renal necrosis. This is when an ECG is done and atrial fibrillation is detected. The second major danger of atrial fibrillation is cardiac insufficiency. Normal people have no problem climbing three floors, but patients with atrial fibrillation have a fast heartbeat, wheezing, swelling of both lower extremities, and even have to sit up at night when they sleep, so they go to the hospital and have poor cardiac function, which means heart failure. There is a clinical diagnosis called arrhythmia cardiomyopathy. The majority of patients who present with heart failure have a fast ventricular rate. The third major danger of atrial fibrillation is the heavy symptoms that affect the patient’s quality of life. After the occurrence of atrial fibrillation, patients feel very uncomfortable, especially female atrial fibrillation patients, the attack will be palpitations, panic, chest tightness, etc., which seriously affects and interferes with the normal order of work, life and study of patients. There are three major strategies for the treatment of atrial fibrillation: first, rhythm control. For first-onset atrial fibrillation, paroxysmal atrial fibrillation, and atrial fibrillation of short duration, atrial fibrillation should be restored to a normal sinus rhythm from a disorganized heartbeat as much as possible, because sinus rhythm can make patients feel more comfortable. Second, ventricular rate control. If atrial fibrillation cannot be reverted, such as permanent atrial fibrillation there is no way to return to sinus rhythm with drugs or catheter ablation. For such atrial fibrillation, it is important to control the ventricular rate, not to let the ventricular rate is very fast, because the fast ventricular rate will be easy to develop heart failure, or aggravate heart failure. Third, prevention of embolism. As mentioned above, one of the great hazards of atrial fibrillation is thromboembolism, and in order to prevent thromboembolic events, anticoagulation and antithrombotic therapy should be carried out. Anticoagulation therapy currently has mainly traditional anticoagulant drugs and new anticoagulant drugs. Traditional anticoagulants such as warfarin have a history of more than 100 years, and their effects are clear. What is the appropriate INR for the Chinese population? There is a lack of information on this. According to my clinical experience, the reasonable range of INR for Chinese is not necessarily 2.0-3.0. In clinical practice, an INR adjusted to 2.0-2.5 is sufficient in patients who are very old and very light in weight, for example. It is worth mentioning that the patient’s bleeding risk is assessed during anticoagulation in AF and the two are balanced to develop the anticoagulation protocol and INR value. Catheter ablation is a better measure to restore sinus rhythm in patients with atrial fibrillation. A growing number of clinical studies confirm its usefulness. The 2014 AHA/ACC guidelines for the treatment of atrial fibrillation clearly recommend catheter ablation for symptomatic paroxysmal and persistent atrial fibrillation that has failed antiarrhythmic therapy or is intolerable to the patient, level of evidence (Class Ia); catheter ablation should be preferred for patients with recurrent paroxysmal atrial fibrillation, level of evidence (Class Ib). Catheter ablation has been in development for over 30 years and progress has been very rapid. So why such rapid progress? It is not only related to the continuous emergence of new materials and tools, but also to the continuous research on the pathogenesis of atrial fibrillation. As a result, atrial fibrillation catheter ablation strategies have undergone a series of evolutions. Initially, the ablation strategy was pulmonary vein segmental isolation, which had a low success rate and a moderate incidence of pulmonary vein stenosis. Then came the circumferential pulmonary vein isolation, an ablation strategy that not only ablated the trigger foci in the pulmonary veins but also modified the AF matrix in the pulmonary vestibule, and this ablation strategy led to a significant improvement in the success rate of the procedure. The ablation strategy for sustained AF at this time is pulmonary vein isolation + fragmentation potential ablation, but this ablation strategy has a high incidence of postoperative atrial tachycardia. The possible reason for this is that the understanding of fragmentation potentials is not deep enough, such as which fragmentation potentials are active and which are passive? Which ones are atrial fibrillation-causing? It is not very clear. The result is that ablation is performed in areas that should not be ablated. Meanwhile, some central sustained AF ablation strategies are pulmonary vein isolation + linear ablation, such as ablation of the left atrial top line, mitral isthmus line with tricuspid isthmus line, etc. The recurrence rate after the procedure is still relatively high. In the 5-year follow-up of Prof. Ouyang at the Hamburg Center in Germany, it was found that less than 30% of patients maintained sinus rhythm with a single ablation of persistent AF. The possible reason for this is that linear ablation does not achieve bidirectional block, and postoperative recurrence of atrial tachycardia or atrial fibrillation can easily occur because of conduction recovery. Therefore, to date, no satisfactory procedure has been found for atrial fibrillation. Recently, MRI technology has been introduced to catheter ablation of atrial fibrillation, and catheter ablation can increase the success rate of the procedure by designing an ablation strategy based on the degree of fibrosis analyzed by MRI. In view of the difficulty of MRI analysis, which is not yet widespread, many centers have started to design ablation strategies based on the results of left atrial high-density labeling, i.e., continuous atrial fibrillation pulmonary vein isolation with linear ablation of the tricuspid isthmus followed by electrical transection into sinus rhythm and subsequent left atrial high-density labeling. Ablation is performed in conjunction with whether or not a left atrial scar is found on the high-density marker. The ablation strategy for persistent atrial fibrillation was studied in depth at our center. First, a voltage survey was performed on the healthy left atrium, and it was found that the voltage of the normal left atrium should be above 1.3 mV, below 0.4 mv is the scar zone, and between 0.4 and 1.3 is the migration zone. Ablation is very individualized according to the voltage scale measurements. The ablation strategy is designed according to the results of voltage scaling, and one third of the patients only need pulmonary vein isolation. The success rate of the procedure was found to be more than 75% after more than 1 year of follow-up. In addition, this individualized ablation strategy greatly shortens the procedure time and reduces the X-ray exposure time and dose, which is very beneficial to both doctors and patients! 365medical.com: Can you please talk about how to improve and increase the success rate of atrial fibrillation ablation treatment in terms of patient preparation and surgical equipment? Prof. Fengxiang Zhang: What I just talked about is the improvement of catheter ablation strategy, which is a series of advances based on the mechanism of atrial fibrillation. How can the success of catheter ablation be improved? First, patient selection. The guidelines state that left atrial thrombosis is a contraindication to catheter ablation, and all others are relative contraindications. In terms of improving the success rate of catheter ablation, I personally recommend that the left atrium of patients undergoing catheter ablation for atrial fibrillation should not be too large, preferably no more than 55 mm. If the left atrial diameter exceeds 55 mm, although it can be done, the recurrence rate is relatively high. For patients with atrial fibrillation with a left atrium larger than 55 mm, if the arrhythmia cardiomyopathy is caused by the fast ventricular rate of atrial fibrillation, the ventricle can be controlled by medication, plus anticoagulation therapy. With the correction of cardiac insufficiency and the use of drugs to improve myocardial remodeling, the enlarged left atrium can be reversed and reduced, and catheter ablation can be performed after the left atrium is reduced; catheter ablation is less suitable for patients with organic heart disease such as dilated cardiomyopathy. In addition, special attention should be paid to the electrocardiogram when the patient is in atrial fibrillation. If the atrial fibrillation electrocardiogram has a large fibrillation wave, there is a high possibility of conversion in ablation, and if the atrial fibrillation electrocardiogram has no fibrillation wave at all, it means that the atrial fibrosis of this patient is very strong, and the success rate of conversion to sinus rhythm in these patients is not high. To improve the success rate of catheter ablation, we should pay attention to the following aspects: First, it is best to choose general anesthesia, because the respiration of patients under local anesthesia is unstable, deep and shallow, which has an impact on the catheter and the model. In patients under general anesthesia, high-frequency ventilation with a tidal volume of about 300 ml/time and a frequency of 30 times/minute, so that the respiration is very smooth and the impact on the model and the ablation catheter is minimal. Second, the fusion of the left atrial CT with the 3D reconstruction model can help the operator, especially the beginner, to understand the left atrial anatomy, which is helpful to improve the success rate of the procedure. Third, the use of new ablation catheters. For example, pressure-sensing catheters are used clinically, and studies have demonstrated that pressure-sensing catheters can improve the success rate of surgery. Fourth, the clinical application of adjustable curved sheaths. Adjustable curved sheaths can compensate for the deficiencies caused by suboptimal septal puncture sites. It can also increase catheter fit and stability to improve ablation efficiency. Studies have shown that adjustable curved sheaths can improve the success rate of catheter ablation. In conclusion, with the continuous progress of medical technology and in-depth research on the mechanism of atrial fibrillation, I believe that the success rate of catheter ablation of atrial fibrillation will be higher and higher!