起源于主动脉窦频发室性期前收缩的心电生理特征及射频消融治疗

目的报道11例起源于主动脉窦的频发室性期前收缩（premature ventricular contraction,PVC）患者的心电生理特征、射频消融（radiofrequency catheter ablation,RFCA）方法及疗效。方法分析患者术前体表心电图和动态心电图PVC的特点,测量V1或V2导联r波时限和振幅,计算r波与QRS波时限的比值及r波于S波振幅的比值。术中行主动脉窦内激动标测和起搏标测确定PVC起源部位,并行冠状动脉造影辅助定位后行RFCA。结果11例均有频发PVC,5例有反复短阵室性心动过速。下壁导联QRS波呈R形且高大直立,V1导联呈rS型,胸前导联多移行于V3以前,V6导联多呈Rs型或无S波。V1导联r波时限（84.6±9.8）ms,占QRS波时限的50%以上;r/S振幅比值0.72±0.31。有效消融靶点局部电图V波较体表心电图的QRS波明显提前（35.6±8.9）ms,有效靶点放电2～8 s见PVC减少至消失。结论起源于主动脉窦的PVC其下壁导联QRS波呈R形且高大直立,V1或V2导联r波时限宽（〉50%同导联QRS波）,r波振幅高（〉30%同导联S波）;主动脉窦内PVC的射频消融治疗是安全、有效的。     

经主动脉窦途径射频消融心动过速临床研究

目的:探讨经主动脉窦途径导管射频消融治愈的快速性心律失常患者的心电图特点及射频消融情况.方法:回顾性分析17例室性心动过速/室性期前收缩、前间隔房性心动过速及前间隔旁路等该类患者的体表心电图、及消融成功时靶点电图等心电生理学特征.结果:经主动脉窦途径导管射频消融治愈室性心动过速/室性期前收缩12例,其中起源于左冠状动脉窦(左冠窦)10例、右冠状动脉窦(右冠窦)2例;源于无冠状动脉窦(无冠窦)的局灶性前间隔房性心动过速3例及前间隔旁路2例.室性心动过速/室性期前收缩心电图特点:Ⅱ、Ⅲ和aVF导联为高大R波,胸导联R波移行较早,V1导联r/S波振幅比≥30%,r波时限(82.2±16.4)ms,V1导联中r/QRS波时限比≥50%,V5、V6导联为高振幅R波、无s波.有效消融靶点心内电图示心室波明显比体表心电图QRS波提前(35.2±21.6)ms.前间隔房性心动过速均能被心房刺激反复诱发和终止,其心电图特点:房性心动过速时P波间期明显窄于窦律时P波间期,Ⅰ、aVL导联P波正向,Ⅱ、Ⅲ和aVF导联P呈负正双向.在心房标测中提示最早的心房激动在希氏(His)束区,但在主动脉无冠窦内标测的心房激动较His束区的心房波提前,其解剖定位于His束上后方,消融靶点无His束电位.前间隔旁路心电图示:窦性心律时呈窄QRS波形,未见预激波,心动过速呈窄QRS形,在无冠窦内记录到最早心房激动点,且无His束电位.17例均消融成功.结论:源于主动脉窦内的室性心动过速/室性期前收缩、前间隔房性心动过速和前间隔旁路具有相对的心内电生理学特征,常规心内膜途径消融困难时应该考虑从主动脉窦途径标测消融策略,把握消融导管与冠状动脉的关系,导管消融治疗安全而有效.     

主动脉无冠状动脉窦内射频消融治疗频发室性早搏和(或)短阵室性心动过速三例

报道3例无冠状动脉窦内射频消融频发室性早搏和短阵室性心动过速的心电图特点和射频消融结果。室性早搏或室性心动过速均呈左束支传导阻滞图形,胸导联V3R/S>1,1例Ⅰ导联呈现R波,2例Ⅰ导联呈顿挫r波,Ⅱ、Ⅲ、aVF均为高大R波,标测消融确定成功靶点在无冠状动脉窦,术中无并发症,随访20~29个月,1例偶发室性早搏。结论:在主动脉无冠状动脉窦内射频消融是可行的。     

起源于主动脉窦内反复单形室性心动过速和/或频发室性早搏的心电图特征及射频消融治疗

探讨起源于主动脉窦内的反复单形室性心动过速(简称室速)和/或频发室性早搏(简称室早)的心电图特点和射频消融治疗。分析35例该类患者的室速和频发室早的心电图、心内电生理检查和射频消融治疗情况。结果:室性心律失常起源于左冠状动脉窦(简称左冠窦)的30例、无冠状动脉窦3例和主动脉根部左冠窦下2例。左冠窦的心电图特点:Ⅰ和aVL导联为rs、rS或QS波形,Ⅱ、Ⅲ和aVF导联为R波形,胸导联R波移行区在V2或V3导联,V5、V6导联为高振幅R波,无S波;V2导联R高度/S高度比值1.29±0.36。主动脉根部左冠窦下起源的心电图特点:和左冠窦起源室性心律失常的心电图特点基本相同,但V5、V6导联有S波。无冠状动脉窦起源的心电图特点:Ⅰ和aVL导联为Rs或R波形,Ⅱ、Ⅲ和aVF导联为R波形,胸导联R波移行区在V3导联。34例消融成功,手术操作时间65~120min,X光曝露时间12~30min。1例出现冠状动脉前降支急性闭塞。随访2~53个月,无复发病例。结论:起源于主动脉窦内的室速和/或频发室早有其独特的心电图表现,射频消融能安全、有效地根治此类心律失常。     

起源于主动脉窦与二尖瓣环交界处的室性心律失常心电图特征及射频消融

目的研究起源于主动脉窦与二尖瓣环交界处(AMC)室性心律失常的心电图特点及射频消融。方法观察6例起源于AMC的室性心律失常患者心电图特征及射频消融。结果 41例室性心律失常患者成功完成射频消融并且证实其起源部位,其中6例起源于AMC。仅有起源于AMC的室性心律失常心电图表现为右束支传导阻滞,QRS波电轴右偏,V1～V6导联中见到R或Rs波形,下壁导联振幅较高,Ⅰ导联呈Rs或rs形,RⅡ/RⅢ<1。三维激动扩布图可见始于AMC的波阵扩布,随后沿AMC传导至主动脉根部及左室,成功靶点消融时间短于左、右室流出道室性心律失常。结论室性心律失常时V1～V6出现R或Rs波形提示其起源于AMC,射频消融治疗安全、有效。     

起源于主动脉窦的室性心律失常的电生理特点及射频消融治疗

目的研究起源于主动脉窦(ASC)的室性心律失常,包括特发性频发室性早搏和室性心动过速(PVCs/VT)的心电图特点、电生理特征和经射频导管消融治疗方法学。方法 15例频发PVCs/VT患者经右股静脉进右室流出道行最早激动顺序和起搏标测,消融不成功或失败的病例,采用经右股动脉途径行电生理检查,于心室及主动脉窦内标测PVCs/VT时最早心室激动(EVA),进行射频消融治疗,分析其体表心电图特点、电生理检查特征及经射频导管消融治疗结果。结果 15例PVCs/VT患者,1例患者PVCs于无冠窦内消融成功,其体表心电图I导联为顿挫的R波,aVL为rSr波,消融靶点局部心室激动提前体表QRS波18ms,放电1次4s终止PVCs;余14例于左冠窦内标测到EVA,其体表心电图呈不典型左束支传导阻滞伴心电轴右偏,I导联为QS、rsr、rs或rS波,II、III、aVF导联为高振幅R波,V6均无S波,胸前导联R移行区12例位于V1~V3导联,仅2例位于V4导联,V1或V2导联R波时程指数≥50%者10例(71.4%)、R/S波幅指数≥30%者11例(78.6%)。9例即刻消融成功者于左冠窦内标测到的EVA提前于体表心电图QRS波(EVA-QRS时间)(45.1±8.0)ms,而5例消融未成功者EVAQRS时间为(26.4±5.9)ms(P0.05)。9例即刻消融成功者于消融靶点处可记录到位于PVCs/VT QRS波之前的高频低振幅电位(P1),窦性心律时于上述相同消融靶点处可记录到位于QRS波之后的高频低振幅电位(P2),于消融靶点处放电1~3次,3~10s内终止PVCs/VT,消融后9例P2电位均延迟;5例消融未成功者,2例于标测到EVA部位记录到P1电位。随访6个月至8年,10例即刻消融成功患者无复发;另5例消融未成功者1例服用倍他乐克心悸症状明显改善,1例服用心得安,心悸发作次数明显减少;余3例患者症状无改善。1例于左冠窦内消融患者术后24h出现严重心绞痛及心电图缺血改变,经药物治疗5天症状消失,余患者在围术期及长期随访中无手术相关合并症发生。结论起源于ASC或其邻近组织的PVCs/VT,其体表心电图及电生理检查具有一定的特点,ASC内经射频导管消融可根治部分患者此类心律失常,应避免损伤冠状动脉。     

经主动脉窦消融成功的室性心律失常体表心电图特点

目的分析经主动脉窦消融成功的室性心律失常体表心电图特点。方法 36例频发室性早搏/非持续性室性心动过速(PVCs/NSVT)的患者经主动脉逆行途径,在CARTO三维电解剖标测指导下,在主动脉根部-左室流出道衔接部进行三维解剖重建、激动顺序标测和指导消融,且消融成功(1例部分成功),并分析其体表心电图特点。结果 36例患者,经左冠窦消融成功30例(83.3%),右冠窦6例(16.7%)。PVCs在体表心电图均表现心电轴下偏的反复单一形态的QRS波形。经左冠窦消融成功的PVCs/NSVT,Ⅰ导联为R、Rs、rS、r、q或rsr波,Ⅱ、Ⅲ、aVF导联均为高振幅R波,胸前导联PVCs R波移行区位于V_1~V_3导联,且PVCs移行区均早于窦性心律移行区,V_1导联表现为R、Rs、RS、rS或qr波,V_1或V_2导联R/S波幅指数2.64±2.03,R波时限指数0.62±0.12,Ⅲ导联与Ⅱ导联R波振幅比(RⅢ/RⅡ)1.09±0.18,aVL导联与aVR导联QS波振幅比(QSaVL/QSaVR)1.32±0.46。经右冠窦消融成功的PVCs/NSVT,Ⅰ导联为R、Rs、r波,Ⅱ、Ⅲ、aVF导联均为高振幅R波,胸前导联PVCs R波移行区位于V_1~V_3导联,V_1导联表现为R、Rs、rS波,V_1或V_2导联R/S波幅指数0.51±0.38,R波时限指数0.55±0.26,RⅢ/RⅡ0.95±0.23,QSaVL/QSaVR1.12±0.39。PVCs经左冠窦消融成功的V_1或V_2导联R/S波幅指数要高于右冠窦(P<0.05)。结论经左冠窦消融成功的室性心律失常多于右冠窦。体表心电图的相关特征有助于决策主动脉窦内的室性心律失常的具体消融部位。     

起源于左冠状动脉窦及右冠状动脉窦的室性早搏心电图特征分析及射频消融治疗

目的:比较左冠状动脉窦及右冠状动脉窦起源的室性早搏(室早)心电图特征。方法:入选成功行主动脉根部室早消融的患者20例,按消融部位分为左冠状动脉窦室早组(LCC组)15例、右冠状动脉窦室早组(RCC组)5例,比较两组心电图特征。结果:RCC组患者Ⅰ导联均为R波;LCC组患者Ⅰ导联4例为QS波,10例为RS或rs波,1例为R波(χ~2=16.80,P0.01)。与RCC组比较,LCC组患者Ⅲ导联R波振幅增高[(2.01±0.45)mV对(1.45±0.33)mV,P0.05]、aVL导联QS波振幅加深[(1.20±0.24)mV对(0.65±0.21)mV,P0.01]、R波振幅Ⅲ/Ⅱ比值及QS波振幅aVL/aVR比值增大(1.09±0.12对0.80±0.12,P0.001;1.31±0.35对0.60±0.24,P0.001)、Ⅰ导联QRS波时限缩短[(78±32)ms对(120±13)ms,P0.05]、aVL导联QRS波时限延长[(128±14)ms对(100±24)ms,P0.05]。除1例患者因起源点临近左冠状动脉开口而放弃消融外,其余均消融成功。平均随访(13±6)个月,无复发病例及并发症。结论:对于体表心电图提示室早起源于左室流出道的患者,Ⅰ导联R波提示RCC室早,Ⅰ导联RS或rs波提示LCC室早;与RCC室早相比,LCC室早Ⅲ导联R波振幅较高、aVL导联QS波振幅较大、R波振幅Ⅲ/Ⅱ比值及QS波振幅aVL/aVR比值增大。     

右室流出道起源与主动脉窦起源室性早搏的分析

目的 探讨右室流出道起源与主动脉窦起源室性早搏心电图的主要区别.方法 回顾分析因频发室性早搏,心电图室性早搏胸前导联呈左束支传导阻滞,Ⅱ、Ⅲ、aVF导联QRS主波向上,行射频消融成功的患者126例,分为右室流出道（RVOT）起源组66例,主动脉窦（ASC）起源组60例.结果 V1、V2导联R波时限指数和R/S波幅指数ASC组高于RVOT组.胸前导联移行区指数RVOT组高于ASC组.ROC曲线分析胸前导联移行区指数鉴别室性早搏起源有较高价值.结论 心电图呈左束支传导阻滞且Ⅱ、Ⅲ、aVF导联QRS主波向上的室性早搏,分析V1、V2导联R波时限指数、R/S波幅指数和胸前导联移行区指数可判断RVOT起源与ASC起源,指导射频消融治疗.     

体表12导联心电图对特发性流出道室性心动过速的起源灶定位作用

目的分析患者的12导联体表心电图(ECG)形态特征,旨在提出简便的ECG指标来预测特发性流出道室性心动过速起源。方法回顾我院54例经射频导管消融(消融)手术治愈的起源于心室流出道的特发性室性心动过速ECG资料,总结不同部位起源特发性流出道室性心动过速的ECG形态特征。结果不同起源灶有特征性的ECG形态①左心室流出道心内膜起源的ECG100%呈右束支传导阻滞图形,87.5%胸前V6导联出现S波;②左冠状窦起源的100%符合V1或V2导联R/S波幅指数≥30%和R波时限指数≥50%这两个条件;③右心室流出道游离壁起源下壁导联的R波多有切迹,且V2导联的S波振幅较深,胸前导联移行晚。结论12导联体表ECG特征,对特发性流出道室性心动过速起源灶定位有较高的预测价值。     

Ventricular tachycardias mimicking those arising from the right ventricular outflow tract

INTRODUCTION: Ablation of ventricular tachycardia (VT) arising from the right ventricular outflow tract (RVOT) has proven highly successful, yet VTs with similar ECG features may originate outside the RVOT. METHODS AND RESULTS: We reviewed the clinical, echocardiographic, and ECG findings of 29 consecutive patients referred for ablation of monomorphic VT having a left bundle branch block pattern in lead V1 and tall monophasic R waves inferiorly. Nineteen patients (group A) had VTs ablated from the RVOT, and 10 patients (group B) had VTs that could not be ablated from the RVOT. The QRS morphology during VT or frequent ventricular premature complexes was the only variable that distinguished the two groups. During the target arrhythmia, ECGs of group B patients displayed earlier precordial transition zones (median V3 vs V5; P < 0.001), more rightward axes (90 +/- 4 vs 83 +/- 5; P = 0.002), taller R waves inferiorly (aVF: 1.9 +/- 1.0 vs 2.4 +/- 0.5; P = 0.020) and small R waves in lead V1 (10/10 vs 9/19; P = 0.011). Radiofrequency catheter ablation from the RVOT failed to eliminate VT in any group B patient, but ablation from the left ventricular outflow tract (LVOT) eliminated VT in 2 of 6 patients in whom left ventricular ablation was attempted. CONCLUSION: The absence of an R wave in lead V1 and a late precordial transition zone suggest an RVOT origin of VT, whereas an early precordial transition zone characterizes VTs that mimic an RVOT origin. The latter VTs occasionally can be ablated from the LVOT. Recognition of these ECG features may help the physician advise patients and direct one's approach to ablation.     

左束支阻滞型特发性室性心动过速的心电图特征对射频消融成功的影响初探

对心电图呈左束支阻滞型的特发性室性心动过速 (简称室速 )的临床特点和心电图进行分析 ,以了解哪些因素可以预测此类患者从右室流出道行射频消融的成功率。对 2 6例特发性室速的患者进行电生理检查和射频消融手术 ,全部患者室速时的心电图呈左束支阻滞。结果 :2 6例中 ,2 2例于右室流出道进行了成功消融 ,成功和未成功消融的患者临床特征和电生理无明显区别 ,成功消融的患者中胸前V1 导联心电图呈rS型 (1 2例 )和QS型 (1 0例 ) ,而 4例未成功者 ,V1 导联均呈rS型 ,其中 2例经主动脉于左冠状窦消融成功。在成功与未成功消融患者中 ,V1 导联有无R波无明显区别 ,但V1 导联无R波预示室速可以从右室流出道成功消融 ,成功消融的室速患者胸前导联的平均移行区在V4导联 ,而未成功患者胸前导联的移行区在V3 或V2 导联。结论 :某些心电图呈左束支阻滞 ,且额面电轴正常或右偏的特发性室速患者不能成功从右室流出道消融 ,V1 导联有r波且移行区在V3 导联或之前者提示此类心电图特征的室速可能非起源于右室流出道 ,部分可能起源于左室流出道     

现存慢型克山病室性早搏的心电图分析

目的分析慢型克山病人室性早搏在心电图上的有关项目的表现,为克山病的防治研究提供有价值的资料。方法应用心电图记录现存慢型克山病人的室性早搏,分析室性早搏在心电图上的有关项目。结果慢型克山病室性早搏发生的次数最少的1次/分,最多44次/分,平均8.6次/分。单纯偶发或多发的占84%,多源多发占16%。测量室性早搏QRS波时间均值为0.15ms～0.16ms,R波电压均值为0.87mv～1.62mv,T波(正或负)的电压均值0.44mv～0.55mv,T波时间的均值为0.17ms～0.19ms,R/T的均值为2.4～3.9。目测可以看到一个比正常图形提前出现的QRS、T波群,T波与本身的QRS主波方向相反,QRS的主波与正常图形的QRS主波方向相反或一致,不论R波的大或小QRS波的时间比正常图形明显延长,T波的高度或深度较大。QRS波多数有不同程度的顿挫或切迹。结论慢型克山病室性早搏多见偶发或多发,少见多源多发,每分钟发生的频率多数在5次以上。测量的QRS波时间比正常图形(<0.11ms)明显延长,R的平均电压除V1导联大于正常图形外其余导联均在正常范围内。相反方向的R/T值较小,T的(正或负)电压和时间较大和较长。目测室性早搏在心电图上的QRS、T波群和正常图形有明显不同。     

经皮心包穿刺行心外膜室性心动过速射频消融术

目的介绍1例经皮心包穿刺行心外膜室性心动过速(简称室速)射频消融治疗。方法患者女性,45岁,反复心悸、心慌、胸闷2年,伴黑矇2次。心电图提示:室速,心率为188～194次/分,QRS波宽大畸形,Ⅰ、Ⅱ、Ⅲ、aVF、V5、V6导联QRS波主波朝上,并在R波的顶端有明显切迹,V1导联主波朝下。在Carto标测系统指引下行室速射频消融术。结果常规心内膜标测在右室游离壁标测到最早激动点,局部激动时间(LAT)较体表心电图V1导联QRS波提早96 ms,于此处起搏大头时QRS波形与发作时体表心电图相似。应用冷盐水大头以35～40 W、40～50℃在该处及周围反复放电消融不能终止心动过速。在X线透视下行经皮剑突下心包穿刺,送入4 mm磁导航温控大头经心包腔至右室心外膜,在右室游离壁心外膜标测到最早激动点,LAT较体表心电图V1导联QRS波提前109 ms。行右冠状动脉造影后,以温控40 W、55℃,消融10 s,终止室速,巩固放电90 s。术后心电生理检查未能诱发心动过速。术后随访18个月无复发。结论经皮心包穿刺行心外膜消融术是对心内膜消融途径的一种有效补充方法,可以提高室速消融的成功率。     

Long-term results of catheter ablation for ventricular tachycardia in arrhythmogenic right ventricular cardiomyopathy/dysplasia

AimsThis study analyzed the arrhythmogenic substrates and mechanisms of ventricular tachycardia (VT), and long-term outcomes of catheter ablation in patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D).MethodsNine patients (1 female, 40±17 years) with ARVC/D and sustained monomorphic VT (SMVT) exhibiting left bundle branch block morphology of the QRS complex were studied. The diagnosis of ARVC/D was confirmed by means of echocardiography, magnetic resonance imaging, and electroanatomic mapping in all patients.ResultsThe patients underwent 10 ablation procedures. At the initial ablation, the mean VT rate was 196±21 (170–240) bpm. In total, 17 VT types were observed. One VT type with left axis (+I, aVL), or right axis (+II,III,aVF) of the QRS complex was present in 3 and 1 patient, respectively. Two VT types of left and intermediate (+I, II, aVL) axis or of left and right axis of the QRS complex were observed in 3 and 2 patients, respectively. Multiple VT types with left axis QRS complex recurred in 1 patient. One VT displayed characteristics of focal arrhythmia, the mechanism of remaining VTs was clearly macroreentrant. The critical slow-conducting isthmus of the reentry circuit was located at the infero-lateral aspect of tricuspid annulus and was bounded by the annulus and baso-lateral wall scar in 7 VTs; the isthmus was located within the scars in the remaining VTs. During 52±31 (12–93) month follow-up since the last ablation, 8 (89%) patients remained free from any VT recurrence without antiarhythmic drug.ConclusionsPatients with ARVC/D frequently presented ≥1 SMVT type. The critical isthmus of reentry circuit was dominantly located close to the tricuspid annulus. Long-term outcome of extensive endocardial ablation was favorable with isolated VT recurrences in one patient.     

射频导管消融治疗顽固性频发室性早搏伴短阵室性心动过速的体会

报道 2 5例 (男 14例、女 11例 ,年龄 15～ 6 7岁 )顽固性频发室性早搏 (简称室早 )伴短阵室性心动过速 (简称室速 )接受RFCA的治疗结果。采用心室激动顺序与起搏标测法进行室早标测定位 ,标测到室早最早激动点较体表心电图QRS波提前 30ms以上或消融电极起搏心电图QRS波图形与室早图形完全一致时放电消融。结果 :2 5例患者室早起源分别为右室流出道 12例、右室心尖部 5例、左室游离壁 5例、左室近后间隔部 3例。 2 5例中 2 1例成功 (包括 1例频发室早伴短阵多形性室速患者 ) ,成功率为 84 % ,无并发症发生。结论 :RFCA治疗频发单形性室早伴短阵室速安全、有效。     

Postextrasystolic Changes in the Complexity of the QRS Complex and T Wave

We tested the hypothesis that ventricular repolarization of the first sinus beat following a ventricular premature beat (VPB) can be modulated in the absence of clearly discernible T‐wave changes. We applied principal component analysis (PCA) to assess QRS and T‐wave complexity of sinus beats preceding and following VPBs in multiple 10‐second resting 12‐lead electrocardiograms of two subjects with frequent VPBs and no apparent heart disease. In both subjects, T‐wave complexity of the first post‐VPB beat was significantly increased compared to the beats preceding the VPB.     

QRS characteristics fail to reliably identify ventricular tachycardias that require epicardial ablation in ischemic heart disease

Criteria for Epicardial Origin in Ischemic VT. Objectives: We tested proposed algorithms for idiopathic and nonischemic tachycardias for their ability to identify epicardial LV‐VT origins. Backgroud: Several ECG features have been reported to identify epicardial origins for left ventricular tachycardias (LV‐VTs) in the absence of myocardial infarction. Only limited data exist in postinfarction patients. Methods: The QRS features of 24 VTs that were ablated from the epicardium and 39 left ventricular VTs ablated from the endocardium were retrospectively analyzed for various 12‐lead ECG features previously reported. Results: No ECG feature consistently predicted an epicardial LV‐VT origin in infarct‐related tachycardias, with epicardial VTs showing slightly longer QRS durations (189 ± 32 ms in epicardial vs 179 ± 37 ms in endocardial, P = 0.28). Pseudo‐delta duration was 38 ± 27 versus 47 ± 27 ms (P = 0.2), intrinsicoid deflection time 93 ± 35 versus 86 ± 32 ms (P = 0.4), shortest RS 97 ± 38 versus 99 ± 32 ms (P = 0.77), and median deflection index 0.82 ± 0.25 versus 0.87 ± 0.22 (P = 0.43). The finding of a Q wave in lead I and the absence of a Q wave in the inferior leads failed to predict an epicardial origin in superior LV‐VT sites. Q waves in any inferior lead and aVR/aVL‐ratio<1 were not specific for an epicardial origin in inferior sites (all P = ns). Furthermore, all inferior LV‐VTs showed a Q wave in the inferior leads which correlated with pre‐existing Q‐waves in sinus rhythm (P = 0.045). Conclusion : Proposed 12‐lead ECG features for differentiation of epicardial versus endocardial sites for nonischemic LV‐VTs do not reliably identify VTs that require ablation from the epicardium. Endocardial mapping should be the first approach to catheter ablation for VTs in patients with ischemic heart disease. (J Cardiovasc Electrophysiol, Vol. 23, pp. 188‐193, February 2012)