Early diagnosis of atrial fibrillation (AF), the most common cardiac arrhythmia, is receiving increasing attention due to its prevalence and incidence in an aging population, which is increasing every year. Percutaneous catheter pulmonary vein electrical isolation has become an important therapeutic approach that is increasingly being used by physicians in specialized cardiovascular centers to treat symptomatic or pharmacologically ineffective AF. Left atrial enlargement and remodeling is an important promoter of AF and is strongly associated with recurrence after catheterized radiofrequency ablation (ablation) of AF. It has been found that left atrium volume (LAV) measured by multislice spiral CT better reflects the actual size of the left atrium when compared with two-dimensional cardiac ultrasound. Therefore, in this study, 64-slice spiral CT was used to measure LAV to investigate the differences in LAV of different types of atrial fibrillation and the correlation between LAV and recurrence after ablation of different types of atrial fibrillation. 1, Data and methods 1.1 Study subjects 115 patients, 49 male and 66 female, with an average age of (60.8±8.1) years, who underwent atrial fibrillation ablation treatment in our hospital from June 2009 to October 2012 were selected, and the patients were classified into 75 cases of paroxysmal atrial fibrillation group, 25 cases of persistent atrial fibrillation group, and 25 cases of long-term persistent atrial fibrillation group, according to the European Guidelines for the Diagnosis and Treatment of Atrial Fibrillation issued by the European Society of Cardiology in 2010. The patients were categorized into 75 cases in the paroxysmal AF group, 25 cases in the persistent AF group, and 15 cases in the long-term persistent AF group. Paroxysmal atrial fibrillation was defined as those who returned to sinus rhythm within 7d; persistent atrial fibrillation was defined as those who had atrial fibrillation for >7d and required medication or electrical cardioversion to return to sinus rhythm; and long-term persistent atrial fibrillation was defined as those who had atrial fibrillation for >1year and were considered to return to sinus rhythm. Inclusion criteria: (1) no left atrial thrombus detected by preoperative transesophageal echocardiography or 64-slice spiral CT; (2) symptomatic atrial fibrillation that had not been treated medically; (3) no previous atrial fibrillation ablation therapy. Another 25 patients who were admitted to the hospital at the same time without finding atrial fibrillation, without diagnosis of organic heart disease, and underwent 64-slice spiral CT of the heart were selected as the control group, with 9 males and 16 females, and the average age was (60.0±5.0) years old. 1.2 Electrophysiological examination and ablation Under the effect of local anesthesia, the left femoral vein was punctured, and a class 10 coronary sinus electrode was placed, and two septal punctures were performed into the left atrium via the right femoral vein route, and two Swartz sheaths were placed. After pulmonary venography, a pulmonary vein specimen catheter (Lasso) and a three-dimensional electroanatomical specimen system were placed into the pulmonary veins and the left atrium, respectively, through the Swartz sheaths. Under the guidance of the three-dimensional electroanatomical specimen system, the preoperative three-dimensional CT image of the left atrium and the electroanatomical reconstruction system were combined using the Carto-Merge technique to accurately specimen the bilateral pulmonary venous vestibules. The position of the pulmonary veins was surrounded by pulmonary vein ablation, and a step-by-step composite ablation strategy was used in patients with persistent AF, starting with pulmonary vein isolation, followed by isolation of the superior vena cava and the coronary sinus, followed by potentiostatic ablation (including fragmentation potentials, continuous potentials, and potentials with agonistic sequences distal to the ablation catheter and proximal to the catheter, etc.), and finally linear ablation of the tricuspid annular isthmus, the apical line of the left atrium, and the mitral annular isthmus; the first three steps had no The first three steps are in no particular order, and linear ablation is the last step, with no further ablation performed if AF is terminated. The endpoint of ablation was pulmonary vein isolation, and after the ablation of paroxysmal atrial fibrillation, atrial fibrillation could not be induced or persistent atrial fibrillation was electrically resuscitated, and the speckle ablation line was verified for bidirectional conduction block. Ablation parameters were set: power 35W, preset temperature 45°C, and saline infusion rate of 17 ml/min during discharge. 1.3 CT imaging of the left atrial pulmonary vein and measurement of LAV and left atrial anterior volume (LA-Ant)/LAV ratio A 64-slice spiral CT (GE Lightspeed HDCT 64-MSCT) was applied during the 1-week period before the operation, and the images were scanned in the The images were reconstructed in three dimensions on a GE advantage workstation with a reconstruction interval of 0.6 mm and collimation of 0.625 mm. The reconstruction methods were volumetric, multiplanar, and curvilinear reconstruction, which were used to determine the LAV, to clarify the presence of LV thrombus, and to provide a three-dimensional reconstruction of the LV pulmonary veins. the LAV was defined as the volume that excludes the LV auricle and the pulmonary veins. Image analysis revealed that LAV was defined as the volume of the excluded left auricle because of poor left auricle contrast filling in some patients, which affected the accuracy of the 3D reconstruction data. And after cutting along between the pulmonary vein opening and the left auricle and parallel to the posterior wall of the left atrium, the LA-Ant and the left atrial posterior volume (LA-Post) were measured separately, and the ratio of LA-Ant and LAV was calculated. 1.4 Follow-up After ablation, antiarrhythmic drugs were continued for at least 3 months, and oral anticoagulation with warfarin was administered to maintain the international normalized ratio of 2 to 3. Follow-up visits were performed at 1, 3, and 6 months after ablation, which included inquiring about clinical symptoms, electrocardiogram, and 24-h ambulatory electrocardiogram. Post-ablation recurrence was defined as (1) assessment from the beginning of postoperative month 4 to month 6, including: atrial fibrillation detected by 24h ambulatory electrocardiography in those with clinical symptoms; (2) atrial fibrillation detected by electrocardiography; and (3) rapid-type atrial arrhythmia with an episode duration of >30s. 1.5 Statistical methods SPSS 13.0 statistical software was used, and the measurement data were expressed as x±s, and one-way ANOVA was used for comparison between the groups, and the count data were expressed as percentage, and the χ2 test was used, and P<0.05 was considered as the difference was statistically significant. 2, Results 2.1 Comparison of baseline clinical characteristics of patients in each group All patients successfully completed the operation without serious complications such as pericardial compression and cerebral embolism. In the paroxysmal atrial fibrillation group, 36 cases completed pulmonary vein isolation under sinus rhythm, and the remaining 39 cases were in atrial fibrillation before the operation, of which 21 cases were converted to sinus rhythm after completing pulmonary vein isolation; 10 cases were converted to atrial flutter and then converted to sinus rhythm after continuing to complete the tricuspid valve and/or mitral isthmus ablation; 3 cases were converted to sinus rhythm after isolation of the superior vena cava, the apex of the left atrium, and the fragmentation potentials; and 5 cases were converted to sinus rhythm. In the persistent atrial fibrillation group, 10 patients returned to sinus rhythm after completing pulmonary vein isolation; 5 returned to atrial flutter and then went on to complete tricuspid and/or mitral isthmus ablation; 6 returned to sinus rhythm after isolation of the superior vena cava, apex of the left atrium, and fragmentation potentials; and 4 returned to sinus rhythm after electrical cardioversion. In the long-term persistent atrial fibrillation group, 2 cases reverted to sinus rhythm after completion of pulmonary vein isolation; 2 cases reverted to atrial flutter and then went on to complete tricuspid and/or mitral isthmus ablation; 4 cases reverted to sinus rhythm after isolation of the superior vena cava, the top of the left atrium, and the fragmentation potentials; and 7 cases converted to sinus rhythm after electrical cardioversion. Compared with the control group,the anteroposterior diameter of the left atrium was significantly increased in the paroxysmal atrial fibrillation group,persistent atrial fibrillation group,and long-term persistent atrial fibrillation group(P<0.01),and the proportion of coronary artery disease was significantly higher(P<0.05). Compared with the paroxysmal atrial fibrillation group, fasting blood glucose was significantly higher in the persistent atrial fibrillation group (P<0.05).The differences between the 4 groups in terms of age, gender, body mass index, hypertension, diabetes mellitus, blood creatinine, TC, TG, HDL-C, LDL-C and LVEF were not statistically significant (P>0.05). 2.2 Comparison of the three-dimensional structure of the left atrium in each group Compared with the control group, the LAV, LV, LA-Ant, LA-post, and LA-Ant/LAV ratios in the paroxysmal atrial fibrillation group were significantly higher (P < 0.05, P < 0.01); compared with the paroxysmal atrial fibrillation group, the LAV, LA-Ant, and LA-post in the persistent atrial fibrillation group were significantly higher (P < 0.05), and in the long-term persistent atrial fibrillation group, the LAV, LA-Ant, and LA-post were significantly higher (P < 0.05). LAV, LA-Ant and LA-post were significantly higher in the persistent AF group compared with the paroxysmal AF group (P<0.05). Although LA-Ant/LAV tended to increase in the long-term persistent AF group, the difference was not statistically significant (P>0.05). Comparing the LAV, LAV, LA-Ant, LA-Post and LA-Ant/LAV ratios between the persistent AF group and the long-term persistent AF group, the differences were not statistically significant (P>0.05). 2.3 Comparison of recurrence after atrial fibrillation ablation in each group Follow-up ranged from 6 to 46 months, with a mean follow-up of (26±20) months; 102 cases (88.7%) were successfully followed up, and 13 cases were lost. The power of the group was 79% for paroxysmal AF, 56% for persistent AF, and 27% for long-term persistent AF. Univariate analysis of age, sex, body mass index, hypertension, diabetes mellitus, coronary artery disease, left atrial anteroposterior diameter, left auricular volume, LAV, and LA-Ant/LAV ratio showed that predictors of recurrence of AF ablation were left atrial anteroposterior diameter (P=0.02), LA-Ant/LAV ratio (P=0.01), and LAV (P=0.01). Multivariate analysis showed that LAV (OR=0.965, 95% CI:0.937-0.983, P=0.014) and LA-Ant/LAV ratio (OR=0.885, 95% CI:0.821-0.989, P=0.013) were predictive factors for AF recurrence. 3, Discussion China has entered an aging society, and atrial fibrillation has become an important disease plaguing elderly patients in modern society. Numerous studies have shown that atrial fibrillation is closely related to cardiovascular and cerebrovascular events. In this study, we found that compared with the control group, there were structural differences in the left atria of patients in the paroxysmal AF group, persistent AF group, and long-term persistent AF group, involving the LAV and LA-Ant/LAV ratios. Meanwhile, LA-Ant/LAV ratio and LAV were the main predictors of recurrence of AF ablation. Patients with persistent AF have a lower postoperative success rate due to significantly enlarged LAV. It has been reported that the success rate of ablation of paroxysmal AF is significantly higher than that of persistent and long-standing persistent AF, and LAV plays a central role in addition to AF duration. In this study, we found that in addition to LAV, the LA-Ant/LAV ratio is another important factor affecting the prognosis of AF ablation. The LA-Ant/LAV ratio was significantly increased in long-term persistent AF and persistent AF, suggesting a relative asymmetry of the left atrium. This irregular left atrial dilatation may be due to the physical constraints of the spine and sternum and the constant changes in the elastic organization of the left atrium. Enlargement of the left atrium and thickening of the left atrial wall are important factors contributing to chronic atrial fibrillation. The thickness of the anterior wall of the left atrium is greater than that of the posterior wall of the left atrium, and the anterior wall of the left atrium has higher stress and is an important factor in the persistence of atrial fibrillation, while the thickness of the anterior wall of the left atrium by itself does not have a significant effect on atrial fibrillation. However, gradual enlargement of the left atrium and asymmetry of the left atrial structure can facilitate the progression of paroxysmal AF to persistent and long-term persistent AF. Pre-ablation 64-slice cardiac CT, which not only provides data on pulmonary veins, the anatomical structure of the left atrium and its intra-atrial thrombus; but also through data reorganization and processing, it can calculate a more accurate LAV, and through the image-cutting function, it is possible to obtain the LA-Ant/LAV ratio, which can reflect the three-dimensional spatial proportions and structure of the enlarged left atrium. In the present study, preoperative CT imaging of the left atrium and pulmonary veins using 64-slice spiral CT and measurement of the LAV size and LA-Ant/LAV ratio can initially predict the success rate after ablation. The present study is a single-center retrospective study with a small sample size, and more precise quantification is needed in a prospective randomized controlled study with a larger sample size. In conclusion, in elderly patients with AF, LAV and LAV asymmetry are predictive of recurrence after AF ablation, and paroxysmal, persistent, and long-standing persistent AF have a tendency to progressively dilate the left atrium irregularly.The LA-Ant/LAV ratio is a simple figure from volumetric CT that reflects geometric variations of the left atrium and predicts the outcome after AF ablation.