Clinical Study Of Repolarization Dispersion And Ventricular Arrhythmia After Cardiac Resynchronization Therapy

Objective:To determine the time-dependent effect of cardiac resynchronization therapy(CRT)on dispersion of repolarization and ventricular arrhythmia in heart failure patients.Methods:A total of 101 consecutive patents who underwent their first cardiac resynchronization therapy defibrillator(CRT-D)implantation at our center were studied.The electrocardiogram and pacemaker records were collected at pre-operation,immediate post operation,1 month,3,6,and 12 months after device implantation respectively and was analyzed for T-peak to T-end(TpTe)interval and ventricular arrhythmia episodes.Patients were divided into left ventricular(LV)reverse remodeling and non-reverse remodeling groups.Changes of TpTe interval at different period and Ventricular tachycardia(VT)/ventricular fibrillation(VF)episodes were compared between the two groups.LV reverse remodeling was defined as the left ventricular end-diastolic dimension(LVEDD)decreased by at least 10%.Ventricular arrhythmia episodes were classified as sustained VT/VF episodes that required anti-tachycardia pacing(ATP)or shock therapy.Results:TpTe interval decreased significantly at 12 months after CRT-D implantation[102.72± 19.39)ms at 12 months vs.(108.28±18.34)ms at baseline,P=0.025].At the 1-year follow-up,22 patients(22%)experienced appropriate therapy(14 ATP alone and 8 shocks)because of VT/VF episodes(VT episodes,17 patients;VF episodes,5 patients).The occurrence of VT/VF episodes showed time-dependent manner.63.6%of the ventricular arrhythmias happened in the first three months after CRT-D implantation.LV reverse remodeling group(59 patients,58%)demonstrated a great reduction of TpTe interval at 6 months and 12 months after CRT-D[(108.12± 18.78)ms at baseline vs.(100.29±16.37)ms at 6 months(P=0.001),vs.(98.76± 18.51)ms at 12 months(P=0.002)]and had a lower rate of VT/VF episodes(compared with non-reverse remodeling group,log-rank test,P=0.024).Conclusions:After CRT-D implantation,TpTe and the number of VT/VF episodes decreased over time.Patients with LV reverse remodeling had a greart reduction of transmural dispersion of repolarization and a lower rate of VT/VF episodes.Objective:Prolongation of the Tpeak-Tend(TpTe)interval,as a measurement of transmural dispersion of repolarization(TDR),is an independent risk factor for chronic heart failure mortality.However,the cardiac resynchronization therapy(CRT)’s effect on TDR is controversial.Therefore,this study aimed to evaluate CRT’s acute and chronic effects on repolarization dispersion.Furthermore,we aimed to investigate the relationship between repolarization dispersion changes and the prognosis of disease.Methods:The study group consisted of 101 patients treated with CRT-D.According to whether TpTe interval was shortened,patients were grouped at immediate and 1-year follow-up after CRT,respectively.The echocardiogram index and ventricular arrhythmia were observed and compared in these subgroups.Patients were classified as CRT responders in terms of LV reverse remodeling that the left ventricular end-diastolic dimension(LVEDD)decreased by at least 10%.Ventricular arrhythmia episodes were classified as sustained VT or VF that required anti-tachycardia pacing(ATP)or shock therapy.Inappropriate therarpy was excluded from the analysis.Results:43 patients(43%)had shorter TpTe interval immediately after CRT-D operation,while,65 patients(64%)had shorter TpTe interval after 1-year follow-up.At the 6-month follow-up,59(58%)patients were classified as responders based on significant reverse Left ventricular(LV)remodeling.22 patients(22%)experienced appropriate therapy because of ventricular tachycardia(VT)/ventricular fibrillation(VF)episodes.For the acute change groups,the rate of LV reverse remodeling(24 patients[56%]vs.35 patients[60%],P=0.648),Δ LVEF(12.51%±7.78%vs.10.50%±9.61%,P=0.365),ΔLVEDD(-7.19±10.53mm vs.-7.02±9.37mm.P=0.933),and ventricular arrhythmias(11 patients[26%]vs.11 patients[19%],P=0.426)between the TpTe interval immediately shorten and nonshorten groups.However,compared with the TpTe interval at 1-year nonshorten group,the TpTe interval at 1-year shorten group had a higher LV reverse remodeling rate(43 patients[65%]vs.16 patients[44%],P=0.034)a better improvement in LVEF and LVEDD(ΔLVEF,12.66%±1.32%vs.9.00%±10.06%,P=0.04;LVEDD(ΔLVEDD,-7.95± 9.64 mm vs.-5.53 + 10.12 mm,P=0.01),and a low rate of ventricular arrhythmias(8 patients[12%]vs.14 patients[39%],P=0.002).Conclusion:Patients with TpTe shortened at 1 year after CRT had a higher rate of LV reverse remodeling and less VT/VF episodes.The acute changes of TpTe after CRT have minimal value on mechanical reverse remodeling and ventricular arrhythmia.Improved CRT response was the key to improving the prognosis.Objective:The Tpeak-Tend(TpTe)interval represented the difference between eimyocardial repolarization and mid-myocardial repolarization times,as a measurement of transmural dispersion of repolarization(TDR)and has been proposed to be responsible for arrhythmogenic events.However,the predictive value of TpTe interval for ventricular arrhythmias after cardiac resynchronization therapy(CRT)remains to be studied.Therefore,this study aimed to evaluate TpTe interval as risk factors for malignant ventricular arrhythmias in patients with CRT-D.Methods:Between January 2011 and December 2014,we enrolled 101 consecutive heart failure patients treated with CRT-defibrillator(CRT-D).Electrocardiogram(ECG)recordings were conducted at baseline and with 24 hours(immediate)using a standard digital recorder with 12 simultaneous leads.The TpTe interval was averaged for all 12 leads and indicated by TpTebaseline and TpTeimmediate· The implantable cardioverter defibrillator(ICD)shocks or anti-tachycardia pacing(ATP)therapy occurrences after CRT-D were confirmed in all patients by device interrogation at the pacemaker follow-up center.Ventricular arrhythmia.episodes were classified as sustained ventricular tachycardia(VT)or ventricular fibrillation(VF)that required ATP or shock therapy.Inappropriate therapy was excluded from the analysis.According to the occurrence of ventricular arrhythmia after CRT-D,the patients were divided into VT/VF group and No VT/VF group.Compared the baseline data of the two groups and searched the predictors of ventricular arrhythmias after CRT-D.Results:A total of 101 consecutive patients were included.At the 1-year follow-up,22 patients(22%)experienced appropriate therapy(14 ATP alone and 8 shocks)because of VT/VF episodes(VT episodes,17 patients;VF episodes,5 patients).Inappropriate therapy happended in eight patients(8%)including sinus tachycardia in three patients and atrial tachycardia/fibrillation/flutter in five patients.Patients who received appropriate ICD therapy had increased TpTeimmediate(124.27±21.66 ms vs 107.00±15.71 ms;P<0,001)and TpTei-year(120.14±21.15ms vs.97.87±15.89ms,P<0.001).On multivariate Cox regression analysis,TpTe interval immediately after CRT-D implantation was independently associated with the risk of VT/VF episodes(HR:1.052;95%CI:1.030-1.074,P<0.001)and the change of TpTe from immediately after CRT to 1 year also associated with the risk of VT/VF episodes(HR:1.021;95%CI:1.006-1.035,P=0.005).According receiver operating characteristic(ROC)curve,TpTeimmediate≥111.5ms had sensitivity of 72.7%and a specificity of 70.9%in predicting risk of ICD therapy.Moreover,CRT-D patients with a TpTeimmediate≥111.5ms had a significantly higher rate of appropriate ICD therapy based on Kaplan-Meier curves(log rank test x 2=12,580,P<0.001).Conclusions:TpTe interval immediately after CRT-D was an independent predictor of VT/VF episodes at the 1-year follow-up.Increased TpTe interval was associate with increased incidence of ventricular arrhythmias in patients with CRT-D.