Analysis Of The Prognostic Characteristics Of Arrhythmogenic Right Ventricular Cardiomyopathy And Research On The Construction Strategy Of Model Animals

Part Ⅰ Characteristics and Prognosis in Patients with Arrhythmogenic Right Ventricular Cardiomyopathy and Different Ventricular Involvement SubtypesOBJECTIVE Arrhythmogenic right ventricular cardiomyopathy(ARVC)is an inherited cardiomyopathy characterized by progressive loss of right ventricular myocardium and replacement by fibrofatty tissue.In ARVC,biventricular involvement is not rare,while limited data reported the clinical characteristics and long-term prognosis in this population.This study aimed to explore the clinical features in Chinese ARVC population and analyze the clinical phenotypic differences and long-term prognosis in different ARVC subtypes.METHODS From June 2007 to February 2017,consecutive patients with a definite diagnosis of ARVC according to the 2010 revised task force criteria and a cardiac magnetic resonance imaging examination were retrospectively enrolled.According to left ventricular ejection fraction(LVEF),patients were divided into RV group(isolated right ventricular involvement)and BiV group(biventricular involvement).The baseline clinical data and long-term outcomes were collected for analysis.The primary endpoints were all-cause mortality,heart transplantation and the composite endpoint(all-cause mortality or heart transplantation).The secondary endpoint was ventricular tachycardia.Multivariate Cox regression analysis was performed to determine the clinical variables independently predicting the composite endpoint.RESULTS A total of 255 patients(aged 37±15 years,males 183)met the inclusion criteria,including 137 patients in BIV group and 118 patients in RV group.Compared with RV group,BIV group patients had older age,longer disease course,higher incidence of heart failure(28%vs.8%,P<0.001)and syncope(33%vs.21%,P=0.038),prolonged cardiac depolarization(116±44 ms vs.105±25 ms,P=0.010),more frequent T wave inversion(44%vs.19%,P<0.001)in lead V4-V6 on ECG,higher proportion of lower QRS wave voltage(39%vs.15%,P<0.001)in limb leads,001)and much lower right ventricular ejection fraction(28±9%vs.31 ± 9%,P=0.009).During a median follow-up of 66 months,31 patients died(21 in BIV group and 10 in RV group)and 28 patients received heart transplantations(20 in BIV group and 8 in RV group).Ninety-nine cases(72%)in BIV group and 89 cases(75%)in RV group occurred VT events.The cumulative survival,heart transplantation free survival and composite endpoint free survival in BIV group were significantly lower than those in RV group(log rank P<0.05),while there was no difference in the cumulative ventricular tachycardia free survival between these 2 groups.Multivariate regression analysis indicated that syncope history(HR 2.63,95%CI 1.27-5.42,P=0.009),cardiac arrest history(HR 6.68,95%CI 3.44-12.98,P<0.001)and left ventricular ejection fraction(LVEF)(HR 0.96,95%CI 0.94-0.99,P<0.001)were independent predictors of composite endpoint in patients with ARVC and BiV involvement,and an ICD implantation significantly improved the prognosis(HR 0.27,95%CI 0.10-0.76,P=0.012).CONCLUSIONS Biventricular involvement is a common feature in ARVC with more severe clinical manifestations and higher risks of all-cause mortality,heart transplantation and the composite endpoint.Syncope,cardiac arrest,LVEF and ICD implantation could independently predict the composite endpoint in this population.Part Ⅱ Electrophysiological Characteristics and Ablation Outcomes in Patients with Arrhythmogenic Right Ventricular Cardiomyopathy and Biventricular InvolvementOBJECTIVE Patients with arrhythmogenic right ventricular cardiomyopathy(ARVC)have a high risk of ventricular tachycardia(VT)and radiofrequency catheter ablation can reduce the VT burden in these patients.Currently,limited data reported the electrophysiological characteristics and ablation outcomes in patients with ARVC and biventricular involvement.The purpose of this study was to investigate the clinical characteristics,ablation efficacy and predictors of VT recurrence in this population.METHODS From July 2010 to March 2018,consecutive ARVC patients with cardiac magnetic resonance imaging data and undergoing catheter ablation for sustained VT in our hospital were enrolled.According to left ventricular ejection fraction(LVEF),patients were divided into RV group(isolated right ventricular involvement)and BiV group(biventricular involvement).The primary endpoint was VT recurrence,and the secondary endpoints were all-cause mortality,heart transplantation,and the composite endpoint of mortality or heart transplantation.The differences of electrophysiological mapping,catheter ablation and long-term outcomes between these two groups were analyzed.Multivariate Cox regression analysis was used to find out the predictors for VT recurrence in BiV population.RESULTS A total of 98 patients(aged 36 ± 14 years,male 85)met the inclusion criteria,including 50 patients biventricular involvement and 48 with isolated right ventricular involvement.The BIV group had a shorter clinical VT cycle length(305±73ms vs.342±70ms,P=0.036)and a higher VT induction rate during electrophysiological stimulation(90%vs.69%,P=0.009).In BiV group,VT mainly originated from the right ventricle(48/50,96%),and 30%of patients(15/50)presented left ventricular(LV)arrhythmias(12 with premature ventricular contraction;10 with VT).Compared with RV-VT,the LV-VT showed a much shorter cycle length(268±29ms vs.302±49ms,P=0.040),30%of them were complicated with hemodynamic abnormalities,and the VT critical sites mainly located in LV basal inferior wall and LV basal free wall.There was no significant difference in acute ablation success and cumulative VT free survival between these 2 groups.The mean follow-up duration for composite endpoint was 73±26 months.The incidence of composite endpoint in BiV group was significantly higher than that in RV group(log rank P=0.037).Multivariate Cox regression analysis showed that age(HR 0.96,95%CI 0.93-1.00,P=0.041),right ventricular ejection fraction(HR 0.93,95%CI 0.86-0.98,P=0.015)and acute complete ablation success(HR 0.18,95%CI 0.07-0.45,P<0.001)were independent predictors of VT recurrence in patients with ARVC and BiV involvement.CONCLUSIONS Patients with ARVC and biventricular involvement had faster clinical VT and higher VT inducibility,but showed a comparable acute and long-term outcomes of VT ablation.Age,right ventricular ejection fraction and the acute ablation efficacy independently predicted the VT recurrence in this population.Part Ⅲ The T-peak to T-end Interval in Patients with Arrhythmogenic Right Ventricular Cardiomyopathy and its Long-term Risk Stratification ValueOBJECTIVE Arrhythmogenic right ventricular cardiomyopathy(ARVC)is a refractory structural heart disease with a high risk of sudden cardiac death.The T-peak to T-end interval(Tpe)on electrocardiogram can reflect the transmural dispersion of ventricular repolarization,which can be used to as a predictor for malignant arrhythmias and all-cause mortality in a variety of heart diseases.However,its prognostic value in ARVC has not been reported.The purpose of this study was to evaluate the level of Tpe and its risk stratification value in patients with ARVC.METHODS From October 2001 to January 2019,patients with definite ARVC and an implanted implantable cardioverter-defibrillator(ICD)were enrolled.Baseline data,ECG data and device interrogations information were collected.The primary end point was appropriate ICD shock and second endpoint was all-cause mortality.The patients were divided into three groups according to the level of Tpe and heart rate-corrected Tpe(Tpec).Kaplan-Meier curve analysis was used to compare the differences of clinical endpoints.Multivariate Cox proportional hazards model was performed to reveal the clinical variables which could independently predict the primary endpoints.RESULTS A total of 102 patients met the inclusion criteria(age 43 ± 14 years,72 males).The Tpe and Tpec levels in ARVC were 106 ± 32ms and 111 ± 35ms,respectively.During device follow-up of 51 ± 38 months,48 patients occurred appropriate ICD shock therapy.The 5-year appropriate ICD shock therapy rate in the highest Tpec group(>120.6ms)was 2.56 times that of the lowest group(<92.5ms).During the mortality follow-up of 77 ± 44 months,23 patients died.The 5-year mortality in the highest Tpec group was four times that of the lowest group.Univariable cox analysis showed that a longer Tpec could predict appropriate ICD shock and all-cause mortality(P<0.01 for each endpoint).After correction for other covariant predictors,Tpec remained its prediction for shock therapy(HR 1.15,95%CI 1.05-1.25,P=0.002)and overall mortality(HR 1.20,95%CI 1.07-1.33,P=0.001).CONCLUSIONS In patients with ARVC and an implanted ICD,Tpec independently predicts both life-threatening ventricular tachyarrhythmias and overall death.Part Ⅳ The Construction Strategy for Arrhythmogenic Right Ventricular Cardiomyopathy Animal Model and the Effects of Beta BlockersOBJECTIVE Arrhythmogenic right ventricular cardiomyopathy(ARVC)is a rare genetic heart disease with a lack of effective treatments.The existing animal models have incomplete phenotype,which could not completely present the clinical characteristics of ARVC.Beta blockers can improve the long-term prognosis in a variety of cardiovascular diseases,but there is no animal research evidence in ARVC.The purpose of this study is to construct a more representative ARVC animal model,and to explore the pathogenesis of ARVC and the efficacy of beta blockers.METHODS In first part,we used CRISPR/Cas9 technology to construct a PKP2 c.1339delA heterozygous mutation rat model based on the mutation site in an ARVC patient.Then these rats were randomly divided into 6 groups:mutant sedentary group,mutant low-intensity exercise group,mutant high-intensity exercise group,wild-type sedentary group,wild-type low-intensity exercise group and wild-type high-intensity exercise group.The data of ECG and echocardiography parameters were evaluated at baseline,8 weeks and 16 weeks after intervention.Myocardial tissue was extracted for HE staining,Masson staining,oil red-O staining and electron microscopy to evaluate the degree of fibrofatty infiltration and the alterations of myocardial ultrastructure.Transcriptome sequencing,real time q-PCR and western blot were used to detect the protein expressions between ARVC rats and wild-type rats.In second part,these PKP2 mutant rats were randomly divided into four groups:exercise group,exercise+metoprolol group,sedentary group and sedentary+metoprolol group.They were given 16 weeks of high-intensity exercise and drug intervention.The data of ECG,echocardiography,magnetic resonance imaging,right ventricular pressure,pathology and related protein expression levels in each group were detected to evaluate the drug efficacy.RESULTS This PKP2 c.1339dela heterozygous rat model showed a complete ARVC phenotype after long-term high-intensity exercise.It presented spontaneous ventricular arrhythmia,T wave changes,right ventricular dilatation with decreased systolic function,large area of right ventricular myocardial loss with transmural fibrosis scar formation,and lipid droplets infiltration inter-and intra-myocardial cells.High intensity exercise can result in abnormal mitochondrial accumulation and mitophagy dysfunction,and reduce the expression of parkin.Metoprolol can reduce ventricular arrhythmia,right ventricular dysfunction and myocardial fibrosis in rats after high-intensity exercise,and reduce the loss of PKP2 in myocardial tissue.CONCLUSIONS Based on gene editing technology and long-term high-intensity exercise intervention,we successfully constructed a representative animal model with complete ARVC phenotype.High intensity exercise can down regulate the expression of parkin in myocardial tissue and inhibit PINK1 parkin pathway mediated mitochondrial autophagy in ARVC model.Beta blockers can effectively reduce the ventricular arrhythmias and cardiac structural abnormalities caused by exercise in ARVC.