Assessment Of The Affection Of Two Radiofrequency Ablations Strategies On Left Atrial Volume And Function In Patients With Atrial Fibrillation

Objective:Atrial fibrillation(AF) is the most common cardiac rhythm disturbances world widely. Its prevalence doubles with each advancing decade of age, as a risk factor for stroke, and associated with a doubling of mortality in both sexes. The occurrence of AF is related with the diffuse substrates with complex interactions from structural changes, electrophysiological modulation, inflammatory reactions, autonomic balance to genetic predisposition and modification. Although doctors have created a series of ablation strategies, they still cannot treat permanent AF effectively because of the structural remodeling and electrical remodeling of atrium during the long period of AF.The pulmonary veins(PVs) and surrounding ostial areas frequently house focal triggers or reentrant circuits critical to the genesis of AF, circumferential pulmonary vein ablation(CPVA) is reported to be effective in the treatment of paroxysmal and chronic AF, but efficacy is limited permanent AF. Ablation strategies that combined CPVA and other ablations such as high-dominant frequency(DF) and continuous CFAEs site ablation, linear ablation and staged ablation procedure with ostial PV ablation were preformed, but there were also big difference among the studies. CPVA guided by 3D mapping systems(CARTO or EnSite) is currently the major ablation type in China. Some studys proved that areas with complex fractionated atrial electrograms(CFAEs) were ideal target sites for ablations to eliminate AF. Whether CFAEs ablation should be performed after CPVA is still debated.In the current study, we retrospective analyzed 76 patients suffering from AF, observed the affection on morphology and function of left atrium( LA) treated by CPVA and combined CPVA and CFAEs ablation, compared the change of LA volume and Va value. The aim of this report is to assess two radiofrequency ablations strategies on LA substrate, and give an instruction for clinical doctors to choose appropriate ablation strategies.To assess the affection of two ablation strategies, including circumferential pulmonary vein ablation(CPVA) alone and combined CPVA and complex fractionated atrial electrograms(CFAEs) ablation, on morphology of the left artrium(LA) of atrial fibrillation(AF) patients.Methods:AF patients in our hospital underwent ablation from January 2012 to October 2013 were enrolled in the research, and all patients provided written informed consent for ablation. The inclusion criteria that were suitable for undergoing radio frequency ablation( RFCA) of this study were as follows:(1) AF patients had AF symptoms but without LA thrombus;(2) I or III anti-arrhythmic drugs were invalid and unable to tolerate drug side effects;(3) the patients with heart failure or low cardiac output. We excluded the cases that underwent the second ablation when AF recured or atrial tachycardia(AT) occured for the first time.Baseline values were evaluated including the following characteristics: fasting blood-glucose(FBG)、triglyceride(TG)、total cholesterol(TC)、high density lipoprotein cholesterol(HDL-C) 、 low density lipoprotein cholesterin(LDL-C) 、 uric acid(UA) 、renin(ren)、angiotensin-Ⅰ(AT-Ⅰ)、angiotensin-Ⅱ(AT-Ⅱ)、c-reactive protein(CRP)、erythrocyte sedimentation rate(ESR)、P wave width of 12 lead electrocardiogram、left atrial volume(LAV) and diastolic late mitral annular velocity value(Va).According to the stochastic indicator, selected cases were randomly divided into two groups, including group CPVA and group combined CPVA and CFAEs ablation.Oral warfarin was administrated for 3 weeks generally before the operation, and INR(International Normalized Ratio,INR) was kept in the range of 2.0-3.0. If the warfarin was not appropriate, the dabigatran(110mg bid po.) would be chosen. Group CPVA was performed with a 8.5 FSWARTL1 sheath catheter(ST Jude company) by 0.032 inches, 145 cm long thread through right femoral vein. Then the interatrial septum needle was put into the catheter where the top of needle apart away 2cm from the top of the catheter. The puncture device was adjusted to impel the inner scabbard head, and dropped into the garden nest egg. After that, the puncture device was adjusted under the right front angle of 45 degrees to point perpendicularly to the atrial septum. When the inner scabbard withstood atrial septum, the needle punctured and injected with contrast medium to confirm. After the confirmation, the needle was fixed and fed into the inner and outer scabbard, and then the needle and the inner sheath were exited. The Lasso maping elector was put into the orifice of left superior PV. The atrial septum was punctured as above and then left PV and right PV were imagined separately after injecting with contrast medium through the outer scabbard. Confirmed the PV ostia with the CARTO system as follows: confirmed the LA ostia combined with the PV angiography image and spatial orientation of CARTO system through operating the ablation catheter by the technologies of push, rotation,and camber change. Continuous focal ablations were done around the left superior and lower PV and right superior and lower PV. Then, Judged whether electrical isolation between PV and LA by LASSO maping and the information of pacemaker in atria and PV completed or not. If not, mapped transmission gap on the original ablation way and ablating until achieved the ablation terminal.The previous steps of combined CPVA and CFAEs ablation were the same as CPVA procedures. Beginning to find CFAEs area in the atria by CFAEs software attached with CARTO system and gave ablation treatment; the software algorithm followed the way: continuous recorded CFAEs(0.05-0.15mV) lasted for 2.5 seconds, calculated the interval confidence level(ICL) and shortest complex interval(SCI), displayed by levels on 3-dimensional structure chart of LA.Considered to employ cardioversion for patients, administrated Ibutilide 1mg via intravenous injection, if persistent AF or AF attacked in the ablation was not terminated. When the Ibutilide did not work, we would use direct- current cardioversion.Oral warfarin was administrated for 2 to 3 months to maintaine INR at a range of 2.0-3.0 after the operation. After that, oral propafenone and amiodarone selectively depended on the occurrences of AF and AT within 3 months after the operation.Following the processing mode of two ablation strategies of AF, we measured the LA volume and Va value by doppler tissue imaging(DTI), using cardiac ultrasound instrument(PHLIPS iE33 5.1.0.206).Reexamined electrocardiogram, 24 hours dynamic electrocardiogram, LA volume and Va value 6 months after the operation. AF recurrence was defined as AF electrocardiogram. If AT was not examined before the operation, but was recorded by electrocardiogram or 24 hours dynamic electrocardiogram after the operation, then we would define it a new case of AT.Continuous data were expressed as the mean ± standard deviation, whereas categorical variables were presented as number and percentage. Continuous data were analyzed using paired or unpaired Student’s t-test, while categorical demographic and baseline measurements were compared using Chi-square/Fisher’s exact test. Student’s t-test were used to compare changes among inter- and intra- groups, while x2-test was used to compare the rates of the AF recurrence and new AT cases. All statistical assessments were two-sided and evaluated at the 0.05 level of statistical significance.Results:A total of 76 AF patients including 52 men and 24 women were enrolled(average age: 59.36 ± 9.366). A total of 33 AF patients including 20 men and 13 women(average age: 57.48 ± 9.543) underwent CPVA. Other 43 AF patients including 32 men and 11 women(average age: 60.79 ± 9.078) underwent combined CPVA and CFAEs ablation. Demographics and baseline characteristics were obtained for each patient in each group. There were no significant differences in any demographic parameters(p > 0.05).All the 76 patients were conducted ablation successfully without postoperative complications, such as pneumothorax, pericardial tamponade, thromboembolism, PV stenosis, atrial esophageal fistula, etc. After 3 months,no significant difference was found on the all the indexes between before and after CPVA treatment or combined CPVA and CFAEs ablation treatment. After 6 months,the Va value of post-operation in group CPVA was higher than that of pre-operation with statistical significance(p=0.004), but no significant difference was found on the LA volume and other indexes between before and after CPVA treatment. There was no significant difference on both Va value and LA volume before and after combined CPVA and CFAEs ablation. Follow the patients for 6-24 months(average months:15±5.5) after ablation, a total of 12 patients were found AF recurrence(6 patients in group CPVA, 6 patients in group combined CPVA and CFAEs ablation), nine new AT cases occured(4 patients in group CPVA, 5 patients in group combined CPVA and CFAEs ablation). Recurrence rate of AF and AT did not show any significant difference. Similarly, there is no significant difference of LA volume between the two groups. While, we found that Va value of the patients underwent CPVA were higher than that of patients underwent combined CPVA and CFAEs ablation with statistical significance(p = 0.036).Conclusions:From the above results, the present study suggested that CPVA alone performed a better effect on AF patients than co-administration of CPVA and CFAEs ablation. We found that the rate of recurrence of AF and new AT occurrence after combined CPVA and CFAEs ablation was slightly higher than CPVA ablation treatment alone, and the opposite results were found on the comparison of Va value.In the study, Va value after CPVA alone treatment was higher than combined CPVA and CFAEs ablation, indicating that LA pump function was better after CPVA alone treatment.According to the limited number of the patients, we did not study the patients with permanent AF and paroxysmal AF separately. We could not be fully convinced that the performance of CPVA treatment was better than combined CPVA and CFAEs ablation among patients with both permanent AF and paroxysmal AF.In conclusion, CPVA method performs a better effect on AF than the co-administration of CPVA and CFAEs ablation. Because of the limited number of cases in our research and the influence factors of AF and the performance that different catheter ablation may apply to different kind of AF patients, more detailed comprehensive research should be considered. In view of these complicated influencing elements, the ablation strategy would remain controversial for a long time, which requires more mechanism study about AF.