New Methods For Differential Diagnosis Of The Outflow Tract Ventricular Arrhythmia Origin

Background: Outflow tract ventricular arrhythmias(OT-VAs)includes premature ventricular contraction(PVC)and ventricular tachycardia(VT),the majority of idiopathic OT-VAs with a left bundle branch block and inferior axis QRS morphology originate from either the right ventricular outflow tract(RVOT)or the left ventricular outflow tract(LVOT).Objectives: 1.Sought to develop a new ECG criteria for distinguishing LVOT from RVOT origins in patients with idiopathic OT-VAs with lead V3 R/S transition.2.To investigate the diagnostic value of type m QRS morphology at ECG lead I during OT-VAs.3.To investigate the characteristics of ECG and target potential features of PVC in patients with CL/RBBB and whether they are the same as those without CL/RBBB.Methods: 1.We studied OT-VAs with a left bundle branch block pattern and inferior axis QRS morphology in 101 consecutive patients who underwent successful catheter ablation in the RVOT(n = 85)or LVOT(n = 16).The surface ECG during the OT-VAs and during SR beats were analyzed with an electronic caliper.The V1-V3 transition index,V2(R/R+S)PVC/V2(R/R+S)SR transition index,PVC(SV2/RV3)transition index were calculated respectively.2.We retrospectively analyzed 357 PVC patients with successful RF in our hospital.According to the successfully ablated target,the patients were divided into two groups: LVOT group(Group A,n=139),RVOT group(Group B,n=218).The case number of type m QRS morphology at ECG lead I,the amplitude of the lead I QRS wave,the target position,and the target potential of the two groups were compared.3.Retrospective analysis of 8 outflow tract PVC cases with CL/RBBB from August 2009 to June 2017 which underwent successfully RF,the patients were divided into two groups according to the bundle branch block chamber: CRBBB group(group A,n=4);CLBBB group(group B,n=4).At the same time,a case at the same successfully ablated position of other patients without CL/RBBB was set as the control subgroup,compared the ECG and target potential features of PVC between the two groups and subgroups.Results: 1.Firstly,the V1-V3 transition index was significantly larger for RVOT origins than LVOT origins(1.54±1.92 :-4.05± 3.49,p < 0.001).The area under the curve(AUC)for the V1-V3 transition index by a receiver operating characteristic(ROC)analysis was 0.95,with a cut-off value of >-1.68 predicting an RVOT origins with an 98% sensitivity and 69% specificity.Secondly,the AUC for V2(R/R+S)PVC/V2(R/R+S)SR transition index by a ROC analysis was 0.925,with a cut-off value of ≥0.6 predicting an LVOT origins with an 87% sensitivity and 69% specificity.Thirdly,the AUC for the PVC(SV2/RV3)index by a ROC analysis was 0.923,with a cut-off value of ≤1.5 predicting an LVOT origins with an 90% sensitivity and 73% specificity.2.In group A,9 cases with type m QRS morphology at ECG lead I was recorded;in group B,30 cases with type m QRS morphology at ECG lead I was recorded,the incidence rate of group B was larger than group A,with statistical difference(p <0.05).Lead I QRS wave amplitude in group A was larger than group B,with statistical difference(0.38±0.13 m V : 0.21±0.13 m V,P<0.01),but there was no statistical difference of Lead I QRS wave duration between the two groups(129.0±29.4ms : 145.6±26.0m V,P>0.05).Group A successfully ablated target position was located at the anterior side of RCC,group B successfully ablated target position was located at septal side of the junction between RVOT free wall and septal wall near the pulmonary valve.The V-QRS interval of group A was smaller than group B,with statistical difference(31±12.3m V : 21±5.7m V,P<0.05).3.Except one case successfully ablated in the GCV with precordial R/S>1 transition at V1 in group A and one case successfully ablated in the RCC with precordial R/S>1 transition at V2 in group B,all of the other 6 cases with precordial R/S>1 transition at lead V4.Precordial R/S>1 transition were not later than sinus rhythm(SR)in group B.QRS complex duration were compared between the SR and PVC groups,with no statistical significance(134.38 + 23.80 : 156.75 + 25.93,P>0.05).QRS complex duration with statistical significance in the control group(92.63±5.76 : 140.25±15.97 ms,P<0.05).Conclusions:1.Compared with the V2(R/R+S)PVC/V2(R/R+S)SR and PVC(SV2/RV3)transition index,V1-V3 transition index is more accurate and comprehensive for the prediction of the OT-VAs origin.In the AUC and accuracy,the V1-V3 transition index is superior to the other two previously proposed ECG criteria in analysis of all OT-VAs.2.Successfully ablation target is at LCC/RCC junction,RCC anterior part,septal side of the junction between RVOT free wall and septal wall near the pulmonary valve.The RVOT origin is more often than LVOT origin,with close anatomical position between the two groups.3.Bundle branch block can lead to misjudgment of PVC origin with CL/RBBB during sinus rhythm,the origin chamber of the PVC should be determined according to the mapping and ablation result.