The Effect Of Radiofrequency Ablation On Mechanical Remodeling And Inflammatory Response Of The Left Atrium In Patients With Different Types Of Atrial Fibrillation

Atrial fibrillation is one of the most common arrhythmias in the clinic,and its morbidity and mortality increase gradually with age.Atrial fibrillation has become a significant public health problem.The primary complications of atrial fibrillation are thromboembolism and heart failure.The stroke risk of patients with atrial fibrillation is 4 to 5 times higher than those without atrial fibrillation.Patients with atrial fibrillation with stroke usually have a poor prognosis,high mortality,and high disability.With the prolongation of the duration of atrial fibrillation,the diameter of the left atrium becomes more extensive,the function of the left atrium decreases,and the risk of heart failure increases.Radiofrequency catheter ablation,an effective treatment of atrial fibrillation,is widely used in clinics to restore sinus rhythm,improve cardiac function and quality of life,and has been proven superior to antiarrhythmic drugs.However,for various reasons,the success rate of radiofrequency catheter ablation is not satisfactory,especially for patients with persistent and long-term persistent atrial fibrillation.And although radiofrequency catheter ablation is widely used,its effect on left atrial remodeling in patients with atrial fibrillation is unclear.On the one hand,radiofrequency catheter ablation helps restore and maintain sinus rhythm,which may improve left atrial function.On the other hand,it will also cause iatrogenic myocardial injury in the left atrium,which may further worsen the function of the left atrium.Previous studies in our center have shown no significant difference in the effect of cryoballoon ablation and radiofrequency catheter ablation on left atrial function in patients with paroxysmal atrial fibrillation.However,few studies have evaluated left atrial remodeling after radiofrequency catheter ablation of different types of atrial fibrillation.Studies have shown that patients with persistent atrial fibrillation have more extensive myocardial fibrosis and lower left atrial strain than patients with paroxysmal atrial fibrillation.To explore further the degree of improved left atrial function by radiofrequency catheter ablation in patients with persistent atrial fibrillation.It can provide a reference for the formulation of a clinical ablation strategy.The two-dimensional speckle tracking technique(2D-STI)is a new technique for quantitatively evaluating myocardial motor function.It is independent of the Doppler principle and angle-independent,so it has more advantages than tissue Doppler imaging.Recently,some studies have confirmed the reliability of non-invasive 2D-STI in evaluating left atrial function.The mechanical structure of the left atrium is measured by conventional echocardiography,and the strain(S)and strain rate(SR)are measured by 2D-STI,which can comprehensively evaluate the global function of the left atrium.More and more evidence shows that inflammation plays an essential role in the occurrence and development of atrial fibrillation.Systemic inflammation can lead to endothelial injury and dysfunction and is also related to atrial myocardial fibrosis,promoting atrial structural remodeling and electrical remodeling and eventually leading to atrial fibrillation.At the same time,radiofrequency catheter ablation causes myocardial damage,which leads to an inflammatory response and further deterioration of left atrial function.This study analyzed the inflammatory indicators collected to discuss the changes in inflammatory indexes in patients with different types of atrial fibrillation before and after radiofrequency catheter ablation.In addition,in recent years,it has been found that statins have not only lipid-lowering effects but also anti-inflammatory and antioxidant effects.However,it is still unclear whether statins can improve left atrial function after radiofrequency catheter ablation by inhibiting the systemic inflammatory response.Our study aimed to evaluate the changes in left atrial structure,function,and inflammatory markers in patients with non-valvular paroxysmal atrial fibrillation,persistent atrial fibrillation,and long-term persistent atrial fibrillation after radiofrequency catheter ablation.At the same time,whether statins can improve the function of the left atrium was observed.This study is divided into three parts: the first part is the effect of radiofrequency catheter ablation on the structure and function of the left atrium in patients with different types of atrial fibrillation.The second part is the effect of radiofrequency catheter ablation on inflammatory factors in patients with different types of atrial fibrillation.The third part explores the left atrial structure and function of atrial fibrillation after radiofrequency catheter ablation combined with statins.Part One Effect of Radiofrequency Catheter Ablation on Left Atrial Structure and Function in Patients with Different Types of Atrial FibrillationObjective: Radiofrequency Catheter Ablation is widely used in patients with atrial fibrillation,but its effect on left atrial reverse remodeling needs to be clarified entirely.In this study,we compared the effects of radiofrequency catheter ablation on left atrial structure and function in patients with nonvalvular paroxysmal atrial fibrillation,persistent atrial fibrillation,and longterm persistent atrial fibrillation.Methods: In a prospective study,this study included patients with atrial fibrillation who underwent radiofrequency catheter ablation in our hospital from April 1,2016,to August 31,2018.According to the duration of atrial fibrillation,patients were divided into paroxysmal atrial fibrillation group,persistent atrial fibrillation group,and long-term persistent atrial fibrillation group.Echocardiography was performed to evaluate the structure and function of the left atrium before operation and at 1,2,3,4,2,3,6,and 12 months after operation.Left atrial anteroposterior diameter(LAAD)and left atrial vertical diameter(LAVD)were measured by conventional echocardiography.Left maximum atrial volume(LAVmax)and Left minimum atrial volume(LAVmin)were measured by LAAD,and the left atrial emptying fraction(LAEF)was calculated.The strain and strain rate curves of each segment of the left atrium were obtained by two-dimensional speckle tracking imaging(2D-STI).The average peak strain(S)of the left atrium during the left ventricular systole and the peak strain rate of the left atrium(SRs,SRe,SRa)during early and late left ventricular diastole were measured and calculated.Results: A total of 180 patients were included,including 60 patients with paroxysmal atrial fibrillation(mean age 56.9±10.8 years,male 34),60 patients with persistent atrial fibrillation(mean age 61.3±9.7 years,male 37),and 60 patients with long-term persistent atrial fibrillation(mean age 60.9±7.7 years,male 30).Regarding left atrial structure,LAAD,LAVD,LAVmax,and LAVmin in the persistent AF group and long-term persistent AF group were higher than those in the paroxysmal AF group before the operation.The above indexes decreased in the persistent AF group and long-term persistent AF group after the operation(P<0.001).LAAD,LAVD,LAVmax,and LAVmin in the paroxysmal atrial fibrillation group decreased within one year,but the difference was not statistically significant(P>0.006).LAAD and LAVD decreased significantly three months after the operation in the persistent AF group(P<0.001),LAAD decreased significantly two weeks after the operation in the long-term persistent AF group(P<0.001),but LAVD did not decrease significantly during follow-up(P>0.006),LAVmax and LAVmin began to decrease significantly at 1-3 weeks after operation in persistent atrial fibrillation group and long-term persistent atrial fibrillation group,and then continued to decrease.Regarding left atrial function,there was no significant change in LAEF,S,SRs,SRe,and SRa in the paroxysmal AF group within one year(P>0.006),but there was still a trend of improvement.LAEF and S in the persistent atrial fibrillation group and the long-term persistent atrial fibrillation group increased significantly one week after the operation(P<0.006)and then continued to rise.The absolute values of postoperative SRs and SRa in the persistent atrial fibrillation and long-term persistent atrial fibrillation groups were significantly higher than before the operation.Still,the absolute values of SRe had no significant difference compared with those before the operation but had an upward trend.Summary: radiofrequency catheter ablation changes left atrial structure and function in patients with different types of atrial fibrillation.1)the effect of radiofrequency catheter ablation on left atrial structure: the improvement of left atrial diameter and left atrial volume in patients with persistent atrial fibrillation and long-term persistent atrial fibrillation was significantly better than that in patients with paroxysmal atrial fibrillation.2)effect on left atrial function: LAEF and S in patients with paroxysmal atrial fibrillation were improved within one year,but there was no significant difference.LAEF and S in patients with persistent atrial fibrillation and long-term persistent atrial fibrillation were significantly improved within one year after the operation.3)Radiofrequency catheter ablation can significantly improve the structure and function of the left atrium in patients with atrial fibrillation,resulting in reverse remodeling of atrial fibrillation,especially in patients with persistent atrial fibrillation and long-term persistent atrial fibrillation.Part Two Effect of radiofrequency ablation on inflammatory factors in patients with different types of atrial fibrillationObjective: Inflammatory response and inflammatory factors play an important role in the occurrence and maintenance of atrial fibrillation.Moreover,inflammation-related indicators can predict the recurrence of atrial fibrillation.Based on this,this study analyzed the inflammatory indicators collected to discuss the changes in inflammatory indexes in patients with different types of atrial fibrillation before and after radiofrequency catheter ablation.Methods: 180 patients with atrial fibrillation were treated with radiofrequency catheter ablation in our hospital from April 1,2016,to August 31,2018.According to the duration of atrial fibrillation,patients were divided into paroxysmal atrial fibrillation group,persistent atrial fibrillation group,and long-term persistent atrial fibrillation group.Before the operation,routine tests and examinations were perfected,and the CHA2DS2-VASc score and HAS-BLED score were performed to evaluate the risk of bleeding and stroke fully.The numbers of neutrophils(Neutrophil,Ne),lymphocytes(Lymphocyte,Ly),and C-reactive protein(C-reactive protein,CRP)were measured before the operation.One day,two days,three days,one week,two weeks,and three weeks,three weeks,four weeks,two months,and three months after the operation,and the absolute ratio of neutrophils to lymphocytes(Neutrophilto-lymphocyte ratio,NLR)was calculated.Results: A total of 180 patients were included,including 60 patients with paroxysmal atrial fibrillation(mean age 56.9±10.8 years,male 34),60 patients with persistent atrial fibrillation(mean age 61.3±9.7 years,male 37),and 60 patients with long-term persistent atrial fibrillation(mean age 60.9±7.7 years,male 30).The changing trend of NLR in the three groups was similar.NLR peaked one day after the operation,decreased significantly within one week,and almost returned to the preoperative level 1 month after.The changing trend of postoperative CRP in the three groups was slightly different.In the paroxysmal atrial fibrillation group,the postoperative CRP increased gradually,peaked two days after the operation,decreased gradually,and reached a similar level 2 weeks after.In the persistent atrial fibrillation group and the long-term persistent atrial fibrillation group,CRP increased gradually after the operation,peaked three days after the operation,then decreased gradually,and reached a similar level two weeks after the operation.Summary: Inflammatory markers increased significantly within 1-3 days after radiofrequency catheter ablation but returned to preoperative levels within 2-4 weeks.The inflammatory indexes of different types of atrial fibrillation increased after the operation and then decreased to the average level.Our results suggest that inflammation is involved in different types of atrial fibrillation ablation,especially in persistent atrial fibrillation and long-term persistent atrial fibrillation.Part Three Study on left atrial structure and function after radiofrequency ablation of atrial fibrillation combined with statinsObjective: Studies have shown that statins can improve the survival rate of patients with acute stroke and atrial fibrillation.In addition,studies have shown that statins can reduce the recurrence rate of atrial fibrillation after electro-cardioversion in patients with atrial fibrillation.However,there are few reports on whether statins can reduce the effect of statins on cardiac function after radiofrequency catheter ablation.Based on this,to explore the changes in left atrial structure and function after radiofrequency catheter ablation of atrial fibrillation combined with statins to provide a new research direction for reducing the recurrence rate of atrial fibrillation after radiofrequency catheter ablation and provide a new treatment for the clinic.Methods: This study included 180 patients with atrial fibrillation treated with radiofrequency catheter ablation in our hospital from April 1,2016,to August 31,2018.According to the intervention of statins,the patients were divided into a statin group(n=90)and a non-statin group(n=90).Patients in the statin treatment group were treated with Atto vastatin 20mg(Pfizer)every night from 3 days before the operation to 1 year after.Patients in the nonstatin treatment group did not use statins all the time and were excluded if they had to be used in exceptional circumstances.Before the operation,routine tests and examinations were perfected,and the CHA2DS2-VASc score and HAS-BLED score were performed to evaluate the risk of bleeding and stroke fully.Cardiac structure and function were repeated before surgery and at 1,2,3,4,2,3,6,and 12 months after surgery.Results: Regarding left atrial structure,LAAD,LAVmax,and LAVmin were followed up at each time point after the operation,and there was no significant difference between statins and non-statins.Similarly,in terms of left atrial function,there was no significant difference in LAEF,S,SRs,SRa,and SRe at each time point of postoperative follow-up between statins and non-statins.Summary: Overall,patients who regularly took regular doses of statins did not benefit significantly over the next year from the point of view of atrial structure and function.It is suggested that in patients who have undergone structural remodeling,even if patients can benefit from surgery,they cannot benefit from statins.Combined with previous studies,we can conclude that preventing atrial fibrillation’s occurrence,development,and recurrence is vital. Sometimes prevention may be more important than cure.Conclusions: 1.We conducted a comparative study on the effects of radiofrequency catheter ablation on the left atrial structure and function in patients with different types of atrial fibrillation,and the results showed that radiofrequency catheter ablation treatment could significantly improve the left atrial structure,LAEF,and left atrial strain in patients with persistent and long-duration atrial fibrillation.For patients with paroxysmal atrial fibrillation,radiofrequency catheter ablation tended to improve atrial structure and function,but there was no statistical difference.2.We conducted a comparative study on the effects of radiofrequency catheter ablation on inflammatory factors in patients with different types of atrial fibrillation.The results showed that inflammatory indicators of different types of atrial fibrillation increased after surgery and then decreased to normal levels.The inflammatory response of patients with persistent and longduration atrial fibrillation was significantly more robust than that of patients with paroxysmal atrial fibrillation.3.We studied the effect of oral statin on the left atrial structure and function of patients with atrial fibrillation ablation.The results showed that chronic statin administration had no significant effect on the atrial structure and function of patients with atrial fibrillation.