| [Background]Wolff-Parkinson-White(WPW)is a pre-excitatory syndrome of the heart caused by an accessory pathway(AP).AP-mediated persistent or repetitive supraventricular tachycardia(SVT)can cause dilated cardiomyopathy.However,it is reported that in the absence of documented SVT,some patients with obvious ventricular pre-excitation,whether children or adults,will develop left ventricular insufficiency and dilated cardiomyopathy.Pre-excitation through AP may affect the left ventricular wall motion,so the degree and position of pre-excitation myocardium may be important factors in determining overall ventricular function.If true,inhibiting or eliminating pre-excitation will reverse the remodeling of ventricular mechanics.However,there is no systematic study on the effect of ventricular pre-excitation at different auxiliary pathway positions on cardiac function,especially in adult patients who are exposed to auxiliary pathways for a long time.Radiofrequency catheter ablation(RFA)of AP is an established treatment for symptomatic WPW syndrome,but its application in asymptomatic patients remains controversial.In addition,a recent study showed that left ventricular(LV)dyssynchrony in asymptomatic WPW syndrome is a risk factor for the development of dilated cardiomyopathy.However,the use of RFA in reducing or eliminating the pre-excitation-induced dyssynchrony remains unclear.[Objectives]The present study aimed to determine the effect of accessory pathway location on cardiac function in adult patients and assess the extent of reverse remodeling produced by RFA.Additionally,we examined the relationship between cardiac functions with cardiac dyssynchrony and initial QRS duration.[Methods]1.Study Patients and DesignA total of 80 consecutive patients with WPW syndrome who received catheter ablation in our hospital from January 2018 to June 2019 were included.Inclusion criteria:Patients with diagnostic criteria for WPW,aged from 18 to 70 years old,were enrolled.All patients had normal sinus rhythm and no tachycardia for at least one week.None had a cumulative arrhythmia burden of 5 hours per month.All patients stopped antiarrhythmic drugs for a period of at least five half-lives of these drugs before ablation.Exclusion criteria:We excluded patients with known cardiac or noncardiac disease,including hypertension,bundle branch block,diabetes,hyperthyroidism,liver or kidney dysfunction,or acute infection.Patients with multiple auxiliary pathways and intermittent pre-excitation evaluated in electrophysiological studies were also excluded..Patients were divided into four groups based on the location of the AP:septal,right free wall,left free wall,and concealed.During recruitment,once 20 patients are enrolled in any group,the enrollment stops in that group.The study met medical ethical standards and has been approved by the ethics committee.Written informed consent was obtained from each patient.Demographic data were obtained from medical records.Laboratory data,including NT-proBNP levels,were assayed using standard laboratory procedures at the Department of Clinical Laboratory of our hospital.2.ElectrocardiogramBefore and after RFA,all patients had a 12-lead ECG during sinus rhythm.QRS duration measurements were automatically performed.3.EchocardiographyBefore catheter ablation and three months later,transthoracic echocardiography was performed by a single physician blinded to the ECG and electrophysiological findings.4.Electrophysiological Study and RFAElectrophysiological studies and RFA were carried out according to standard techniques.The following parameters were examined:AH interval during sinus rhythm,HV interval during sinus rhythm,tachycardia cycle length,ERPa and ERPr.Standard electrophysiological actions determined the location of the accessory pathway.An 8Fr deflectable catheter with a 4mm ablation tip was inserted through the right femoral vein for mapping and catheter ablation.The radiofrequency current was set at a maximal power output of 30 W and an upper temperature limit of 55℃.5.Statistical AnalysisContinuous variables are presented as mean ± standard deviation(SD).Differences between two groups were compared using Student’s t-test while comparisons among more than two groups were conducted using one-way analysis of variance with Bonferroni’s post hoc test.Categorical variables are presented in frequency(number)and proportion(%).The χ2 test was used to compare differences between groups.Correlations between nonparametric variables were tested using Pearson’s correlation coefficient.A p-value<0.05 was considered statistically significant.All statistical analyses were performed using SPSS 23.[Results]1.General Clinical CharacteristicsThere were no significant differences among the four groups in terms of age,sex,weight,heart rate,and laboratory data,including blood urea nitrogen,creatinine,estimated glomerular filtration rate,high sensitivity C-reactive protein,and Cystatin C levels.None of the patients suffered from incessant tachycardia,rapid conduction of atrial fibrillation via the accessory pathways,or other arrhythmias that might have contributed to the reduced LV function.2.Electrocardiogram DataAll patients achieved a long-term success of RFA with no tachycardia recurrence during follow-up.3.Echocardiographic FindingsThere were significant differences in LVEF between the four groups(p<0.001).LVEF was significantly lower in patients with septal accessory pathways and right free wall accessory pathways than in patients with left free wall accessory pathways and concealed accessory pathway,respectively(P<0.001).Two patients(10%of the septal group)and one patient(5%of the right free wall group)had LVEF<50%.None of the patients in the left free wall accessory pathway and concealed accessory pathway groups had LVEF<50%.After ablation,LVEF increased significantly in septal and right free wall accessory pathway groups(p<0.001).There were no significant differences in LVEDd among the four groups before and after ablation.Before ablation,intraventricular LV synchrony decreased in the septal and right free wall accessory pathway groups,which was demonstrated as a significant increase in SPWMD(p<0.001).After ablation,SPWMD was significantly shorter in the septal and right free wall accessory pathway groups(P<0.001,respectively).No changes were observed after ablation in the other two groups.Interventricular synchrony did not differ between the four groups pre-and after ablation,assessed by IVMD(p=0.092,p=0.06,respectively).4.Electrophysiological DataOn the other hand,HV intervals were shorter in the WPW patients than concealed accessory pathway group.The effective refractory period of the accessory pathway and tachycardia cycle length were not different among the four groups.All RFA procedures were performed without complications.5.Plasma NT-proBNP Levels in PatientsThe levels of plasma NT-proBNP were significantly different among the four groups(p=0.039),with a higher NT-proBNP plasma concentration in the septal and right free wall accessory pathway groups compared to concealed accessory pathway group.After ablation,plasma NT-proBNP levels significantly decreased in the septal and right free wall accessory pathway groups(p=0.001).6.CorrelationsThere was a negative correlation between initial LVEF with initial SPWMD and initial QRS duration.It is worth noting that compared with the initial QRS duration,the correlation between SPWMD and LVEF is stronger.[Conclusions]Anterograde conduction with a septal or right free-wall accessory pathway may cause LV dyssynchrony and impair LV function,resulting in decreased LVEF and higher NT-proBNP plasma concentration.Intraventricular LV dyssynchrony appears to be responsible for the pathogenesis of LV dysfunction.Radiofrequency ablation of accessory pathways results in decreased BNP levels,normalized QRS duration,mechanical resynchronization,and improved LV function.Recovery of SPWMD was observed in all affected patients.Even in the absence of arrhythmias,decreased LV function and echocardiographic dyssynchrony may imply premature RFA procedure in patients with manifest septal or right free wall accessory pathway. |
