Ventricular tachycardia with participation of the left bundle-Purkinje system in patients with structural heart disease: identification of slow conduction during sinus rhythm

Introduction: Idiopathic left ventricular tachycardia (VT) originating from the left posterior fascicle can be eliminated by ablation at sites with abnormal diastolic potentials (DPs) during sinus rhythm. We investigated whether such DPs can also be recorded in patients with structural heart disease and VT involving the left bundle-Purkinje system.
Methods and Results: Eight patients (mean age 67 ± 11 years) with nonischemic cardiomyopathy (n = 5) or prior myocardial infarction (n = 3) presented with VT involving the left bundle-Purkinje system (cycle length 376 ± 45 ms). Three types of VT were observed: macroreentrant VT with participation of both left bundle fascicles in three patients, fascicular VT involving the left posterior fascicle in two patients, and scar-related VT with Purkinje fibers as part of the reentrant circuit in three patients. In all patients, abnormal isolated DPs of low amplitude with a QRS—earliest DP interval of 374 ± 86 ms were found during sinus rhythm in the mid- or inferior left ventricular septum in areas with Purkinje potentials. The abnormal DPs during sinus rhythm coincided or were in proximity to DPs during the VT in six patients. VT ablation targeting the sites with the earliest abnormal DPs during sinus eliminated the VT in 7 of 8 patients with freedom from VT recurrence in six patients during the follow-up of 11 ± 5 months.
Conclusions: Isolated DPs during sinus rhythm were found in proximity to the posterior Purkinje network in patients with VT involving the left bundle-Purkinje system associated with heart disease and can be used to guide successful catheter ablation.     

Characteristics of Sinus Rhythm Electrograms at Sites of Ablation of Ventricular Tachycardia Relative to All Other Sites: A Noncontact Mapping Study of the Entire Left Ventricle

Noncontact Mappin g of VT During Sinus Rhythm. Introduction : Regions of the diseased ventricle that activate abnormally during sinus rhythm (SR) may be the areas of slow and disorganized conduction that form the diastolic pathway through which reentry may occur during ventricular tachycardia (VT).
Methods and Results : We examined features of electrograms recorded during SR that might indicate a site suitable for ablation of VT using a noncontact mapping system, which enables reconstruction of > 3,000 electrograms. Preablation SR electrogram characteristics at sites of successful radiofrequency ablation (RFA) were examined in 13 patients with 53 VTs. Timing of onset, lateness of activity, electrogram duration, and number of baseline crossing events of reconstructed electrograms at the sites of successful RFA were compared with the electrograms of latest onset, latest activity, longest duration, and most baseline crossing events of all ventricular sites. Onset of activation at sites of successful RFA were 26.9 ± 25.2 msec (mean ± SD) earlier than (and 2.9 ± 1.7 cm away from) the site of latest onset of SR activation. Electrogram duration at sites of successful RFA was 83%± 14.6% of (and 4.3 ± 1.8 cm away from) the longest electrogram. The baseline crossing events at sites of successful RFA were 53%± 22% of (and 4.9 ± 1.9 cm away from) the most fractionated electrogram. The latest activity at sites of successful RFA was 21.6 ± 24.8 msec earlier than (and 4.3 ± 1.6 cm away from) the site of latest activity.
Conclusion : Although the site of latest onset of endocardial activation during SR proved to be the most sensitive indicator, the characteristics of SR electrograms did not usefully predict successful ablation sites.     

The morphology changes in limb leads after ablation of verapamil-sensitive idiopathic left ventricular tachycardia and their correlation with recurrence

Objectives: This study was designed to explore the morphology changes in limb leads of ECGs after successful ablation of verapamil sensitive idiopathic left ventricular tachycardia (ILVT) and their correlation with tachycardia recurrence.
Methods: Between January 2001 and December 2006, 116 patients who underwent successful ablation of ILVT were included in the study. Twelve-lead surface ECG recordings during sinus rhythm were obtained in all patients before and after ablation to compare morphology changes in limb leads.
Results: The ECG morphology changes after ablation were divided into two categories: one with new or deepening Q wave in inferior leads and/or disappearance of Q wave in leads I and aVL, and the other without change. The changes in any Lead II, III, or aVF after ablation occurred significantly more in patients without recurrence of ventricular tachycardia (VT) (P < 0.0001, 0.002, and 0.0001, respectively). The patients with recurrence of VT tended to have no ECG changes, compared with those without recurrence of VT (P = 0.009). The sensitivity of leads II, III, and aVF changes in predicting nonrecurrence VT were 66.7%, 78.7%, and 79.6%, specificity were 100%, 75%, and 87.5%, and nonrecurrence predictive value of 100%, 97.7%, and 98.9%, respectively. When inferior leads changes were combined, they could predict all nonrecurrence patients with 100% specificity.
Conclusions: Successful radiofrequency ablation of ILVT could result in morphology changes in limb leads of ECG, especially in inferior leads. The combined changes in inferior leads can be used as an effective endpoint in ablation of this ILVT.     

Patients with Scar-Related Right Ventricular Tachycardia: Determinants of Long-Term Outcome

Introduction: Patients with established arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) based on task force (TF) criteria and ventricular tachycardia (VT) are at risk of VT recurrence and sudden death. Data on patients with VT due to right ventricular (RV) scar not fulfilling TF criteria are lacking. The purpose of this study was to assess the long-term arrhythmia recurrence rate and outcome in patients with scar-related right VT with and without a diagnosis of ARVC/D.
Methods: Sixty-four patients (age 43.5 ± 15 years, 49 males) presenting with nonischemic scar-related VT of RV origin were studied. Scar was identified by electroanatomical mapping, contrast echocardiography, and/or magnetic resonance imaging (MRI). Patients were evaluated and treated according to a standard institute protocol.
Results: Twenty-nine (45%) patients were diagnosed with ARVC/D according to TF criteria (TF+) and 35 (55%) with RV scar of undetermined origin (TF–) at the end of follow-up (64 ± 42 months). Patients were treated with antiarrhythmic drugs, radiofrequency catheter ablation, and/or implantable cardioverter-defibrillator (ICD) implantation. VT recurrence-free survival for TF+ and TF– was 76% versus 74% at 1 year and 45% versus 50% at 4 years (P = ns). Patients with fast index VT (cycle length [CL]≤ 250 ms, n = 31) were more likely to experience a fast VT during follow-up than patients with a slow index VT (CL > 250 ms, n = 33) (61% vs 3%, P < 0.001).
Conclusions: Scar-related RV VTs have a high recurrence rate in TF+ and TF– patients. Patients presenting with a fast index VT are at high risk for fast VT recurrence and may benefit most from ICD therapy.     

三维标测指导致心律失常性右心室心肌病室性心动过速的射频消融

目的介绍致心律失常性右心室心肌病（ARVC）室性心动过速（室速）的三维标测方法及其消融策略。方法21例ARVC室速患者,因1—4种抗心律失常药物治疗无效,临床上呈反复发作、无休止发作或植入型心律转复除颤器（ICD）植入后频繁放电治疗,接受导管消融治疗。其中,男性19例,女性2例,平均年龄（32±12）岁。9例患者接受电解剖（Carto）标测,12例患者接受非接触标测（EnSite—Array）。在首先明确病变基质的基础上,通过激动标测、拖带标测及起搏标测,分析心动过速的起源、可能的传导径路及其出口以及它们与病变基质的关系。通常于心动过速的出口处及其周边行局灶消融,术中病变基质周边的延迟激动电位应一并消融。结果21例患者,2例呈无休止发作,1例患者表现为频繁室性早搏及加速性室性自主心律,余18例患者消融中共诱发出34种心动过速。所有心动过速均呈左束支阻滞形,平均心动过速周长为（289±68）ms。16例患者（28种室速）消融治疗即刻成功,3例患者（7种室速）部分成功,2例患者（2种室速）消融失败,即刻消融成功率76．2％。所有患者消融术后继续服用抗心律失常药物。平均随访6～30（1d±7）个月,成功患者中2例复发,其中1例再次消融成功;未达即刻成功的5例患者,经抗心律失常药物治疗后,均无室性心律失常事件发生,其中包括1例消融后植入ICD者。结论三维标测系统可首先明确ARVC患者的病变基质,在此基础上结合激动标测和心内各种电刺激技术,可直观显示心动过速的起源、缓慢传导区出口及折返环路,以此制定消融策略可成功治疗ARVC室速。心动过速起源于心肌深部或ARVC病变进展,是消融失败和复发的常见原因。     

致心律失常右室发育不良心肌病的电生理基质和导管消融治疗(附二例报道)

目的报道2例致心律失常右室发育不良心肌病(ARVC)的电生理特征及导管消融结果。方法2例均以室性心动过速(简称室速)为首发症状。在窦性心律下,采用心脏电解剖标测系统构建右室并行起搏标测室速起源点。结果双极电压图上的低电压面积分别为36 cm2和48 cm2,室速起源于低电压的病变心肌与正常心肌的交界区,2例共有4种室速,采用线性消融后4种室速即刻均不能诱发,例2于术后第2天复发,但室率从188次/分降至160次/分,随访9个月和4个月未见室速复发。结论ARVC的电生理基质是病变心肌的低电压区,电解剖标测指导下的线性导管消融是一种有效的治疗方法。     

Identification of an epicardial slow conduction channel using ripple mapping in ablation of postinfarct ventricular tachycardia

An 82‐year‐old man underwent redo catheter ablation of ventricular tachycardia (VT) after anterior infarction. A ripple mapping conducting channel (RMCC) was identified within the anterior scar in the left ventricular epicardium during sinus rhythm. Along the RMCC, delayed potentials during sinus rhythm, a good pace map with a long stimulus to the QRS interval, and mid‐diastolic potentials during VT were recorded, and epicardial ablation at this site eliminated the VT. These findings suggested that the RMCC in the epicardial scar served as a critical isthmus of the postinfarct VT, and ablation targeting the RMCC was effective.     

心室反应在射频消融特发性室性心动过速中作用的临床研究

目的　探讨心室反应 (VR)在射频消融IVT的作用。方法　应用体表心电图、心内膜激动标测及VR相结合的方法射频消融 13例IVT病人。以激动标测初选靶点 ,射频消融试放电产生的VR确定靶点 ,采用VR与VT发作相一致处为靶点消融。结果　 13例IVT即刻消融成功率 13/ 13。VR表现 :(1)窦性心律下消融时出现与VT发作相一致的VR。随后室性心动过速 (VT)中间断出现窦性心律、双发或联律室性早搏 ,最终完全恢复成窦性心律。 (2 )出现与VT发作不一致的VR。结论　以VR与VT发作相一致处作靶点 ,产生与VT发作相一致的VR可被视为有效消融的指标。     

Postmyocardial Infarction Patients Susceptible to Ventricular Tachycardia Show Increased T Wave Dispersion Independent of Delayed Ventricular Conduction

Arrhythmia Markers After Myocardial Infarction. Introduction: Experimentally, both delayed ventricular conduction and nonhomogeneous ventricular repolarization contribute to reentrant arrhythmias. We tested the hypothesis that increased T wave dispersion is independent of delayed ventricular conduction associated with arrhythmia vulnerability in postmyocardial infarction (post-MI) patients.
Methods and Results: We studied 32 post-MI patients with clinical or inducible monomorphic ventricular tachycardia (VT group), 28 post-MI patients without arrhythmias (MI group), and 13 healthy controls, using magnetocardiographic (MCG) mapping with signal averaging. Twelve-lead ECG was the reference. Filtered QRS duration (fQRS) and T wave peak to T wave end interval (TPE) were used as measures of ventricular conduction and nonhomogeneity in ventricular repolarization, respectively. In MCG, the VT group showed the longest fQRS (  135 ± 34  msec vs  114 ± 22  msec in the MI group;  P = 0.012  ). Mean TPE and maximum TPE in VT versus MI groups were  78 ± 9  msec versus  70 ± 6  msec (  P < 0.001  ) and  117 ± 23  msec versus  104 ± 19  msec (  P = 0.020  ), respectively. Maximum TPE did not correlate with fQRS in the VT group (  r = 0.063; P = NS  ) but did correlate in the MI group (  r = 0.396; P = 0.037  ). For identification of post-MI patients prone to VT, selection of cutoff values for fQRS > 140 msec and mean TPE > 81 msec gave sensitivity and specificity of 41% and 89%, and 31% and 96%, respectively. Their combination increased sensitivity to 63% while maintaining 89% specificity.
Conclusion: Post-MI patients susceptible to VT show increased T wave dispersion independent of delayed ventricular conduction.     

致心律失常性右室心肌病室性心动过速的射频消融治疗

目的评价致心律失常性右室心肌病(ARVC)室性心动过速(VT)射频消融的疗效。方法 4例ARVC患者,男3例,女1例,年龄27～62岁,均有反复头昏、心悸、晕厥或黑矇病史。4例患者症状发作时共出现6种形态的VT,频率为130～210次/分。在三维标测系统(CARTO或EnSite Array)指导下行VT消融治疗。结果 4例患者共行6次手术,其中3次采用CARTO系统,3次采用EnSiteArray系统指导。3例完成消融,随访2～19个月,3例患者均无猝死、晕厥或黑矇发生;2例术后一周内复发,但VT的频率减慢,药物能有效控制,术后5～6个月VT不再发作。另1例患者在放电消融过程中VT的频率加快,形态紊乱,蜕变为心室颤动,紧急电复律后转为窦性心律,终止手术。随访6个月,无VT发生。结论致心律失常性右室心肌病VT的射频消融治疗可改善病人的症状。     

Effect of antiarrhythmic therapy on delayed potentials detected by the signal-averaged electrocardiogram in patients with ventricular tachycardia after acute myocardial infarction

The ability of class I and class II antiarrhythmic drugs to either abolish delayed potentials or modify their timing was investigated in 39 patients with spontaneous ventricular tachycardia (VT) after myocardial infarction. Before the study all patients had delayed potentials on the signal-averaged electrocardiogram and inducible VT with programmed stimulation. These investigations were repeated during 67 trials of oral antiarrhythmic therapy (mexiletine 25, quinidine 24, metoprolol 13, disopyramide 2, procainamide 1, drug combinations 2). Delayed potentials were abolished in only 5 trails (7%), which was within the baseline variability of 8.5% for detection of delayed potentials. In the 7 trials in which VT inducibility was suppressed, delayed potentials persisted in 6 and mean ventricular activation time was virtually unchanged (151 ms before drug therapy, 152 ms after). Quinidine, mexiletine and metoprolol caused no consistent change in ventricular activation time. There was also no change in mean ventricular activation time (164 ms before and 163 ms after drug treatment) in patients in whom spontaneous VT did not recur with drug therapy during follow-up. Thus, the tested antiarrhythmic drugs had no consistent effects on presence or timing of delayed potentials on the signal-averaged electrocardiogram, even when VT inducibility was suppressed or recurrence of spontaneous VT was prevented.     

Right ventricular scar‐related ventricular tachycardia in nonischemic cardiomyopathy: Electrophysiological characteristics,mapping, and ablation of underlying heart disease

1 Background

Right ventricular (RV)‐scar related ventricular tachycardia (VT) is often due to arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) or cardiac sarcoidosis (CS), but some patients whose clinical course has not been described do not fulfill diagnostic criteria for these diseases. We sought to characterize the electrophysiologic substrate and catheter ablation outcomes of such patients, termed RV cardiomyopathy of unknown source (RCUS).

2 Methods and results

Data of 100 consecutive patients who presented with RV cardiomyopathy and/or RV‐related VT for ablation were reviewed (51 ARVC/D, 22 CS; 27 RCUS). Compared to ARVC/D, RCUS patients were older (P = 0.001), less commonly had RV dilatation (P = 0.001) or dysfunction (P = 0.01) and fragmented QRS, parietal block, and T‐wave inversion. Compared to CS, R‐CUS patients had less severe LV dysfunction. Extent and distribution of endocardial/epicardial scar and inducible VTs in RCUS patients were comparable with ARVC/D and CS patients. At a median follow‐up of 23 months, RCUS patients had more favorable VT‐free survival (RCUS 71%, ARVC/D 60%, CS 41%, P = 0.03) and survival free of death or cardiac transplant (RCUS 92%, ARVC/D 92%, CS 62%, P = 0.01). No RCUS patients developed new criteria for ARVC/D or CS in follow‐up.

3 Conclusions

Up to one‐third of patients with RV scar‐related VT are not classifiable as ARVC/D or CS. These patients had a somewhat better prognosis than ARVC/D or sarcoid and did not develop evidence of these diseases during the initial 2 years of follow‐up. The extent to which this population comprises mild ARVC/D, CS, or other diseases is not clear.     

致心律失常性右室心肌病的CARTO系统电生理基质标测和射频导管消融

目的应用CARTO系统对致心律失常性右室心肌病(ARVC)患者进行电解剖标测并指导射频消融治疗其室性心动过速(简称室速)。方法入选伴有室速反复发作的25例ARVC患者,年龄36±12岁,男性17例,有家族成员35岁以下早发猝死史3例。术前行常规心电图、心室晚电位、心脏B超检查。在窦性心律或/和心动过速时,电解剖标测三维重建右室。术中6例同时行右室造影检查。根据双极电图电压高低确定疤痕区、正常心肌和临界边缘区。对于折返性室速,线性消融关键峡部或疤痕区与三尖瓣环之间或两疤痕区间;对于局灶性室速,点消融局部最早激动区域。结果 20%(5/25)体表心电图发现前壁或下壁导联Epsilon波,心室晚电位阳性占88%(21/25),心脏B超发现右室不同程度的局部或整体扩张,56%(14/25)可见局部囊袋状向外膨出。所有患者均出现1～5(2±1)种左束支阻滞型室速,其中5例合并频发室性早搏,1例伴心房扑动,1例伴左后间隔旁道。即时消融成功率为72%(18/25)。随访14±10(4～36)个月,原消融成功的5例室速复发。1例消融失败伴晕厥史的患者植入ICD治疗。无手术相关并发症和死亡发生。结论应用CARTO系统电解剖标测可安全有效指导射频消融治疗ARVC患者的室速,有相对较高的失败和复发率。CARTO系统标测的电压图,参考术前心电图、心脏B超及右室造影可了解病变心肌的分布范围,对初步确定室速的病理基质有帮助。     

Effect of Heart Rate on T Wave Alternans

Heart Rate and T Wave Alternans. Introduction : T wave alternans (TWA) is a promising technique for detecting arrhythmia vulnerability. Previous studies in animals demonstrated that the magnitude of TWA is dependent on heart rate. However, the effects of heart rate on TWA in humans and the clinical relevance of this effect remain controversial.
Methods and Results : This was a prospective evaluation of pacing rate and monitoring lead configuration on TWA in subjects undergoing electrophysiologic study. Measurements of TWA were performed on 45 patients in the absence of antiarrhythmic drugs. Recordings were made in normal sinus rhythm and during atrial pacing at 100 and 120 beats/min. Sustained monomorphic ventricular tachycardia (VT) was induced in 29 patients with programmed stimulation. TWA in the vector magnitude lead increased with heart rate, independent of VT inducibility (0.4 ± 0.7 μ V, 1.6 ± 1.9 μ V, and 2.4 ± 2.1 μ V in sinus rhythm and at 100 and at 120 beats/min, respectively; P < 0.001). In addition, the diagnostic performance of TWA for inducible VT was dependent on heart rate (sensitivity 4%, 42%, and 65%, and specificity 100%, 93%, and 63% at 77, 100, and 120 beats/min, respectively). By analyzing orthogonal leads rather than the vector magnitude lead, the sensitivity is increased from 42% to 59% at 100 beats/min, but the specificity is reduced from 93% to 72%.
Conclusion : These results indicate that TWA in humans is strongly dependent on heart rate with regard to both magnitude and diagnostic performance. The optimal heart rate for the measurement of TWA is between 100 and 120 beats/min and multiple leads should be monitored.     

Radiofrequency catheter ablation of left ventricular tachycardia in the normal heart

Background: Radiofrequency (RF) catheter ablation is a safe and effective cure for many forms of supraventricular tachycardia. Its efficacy in the cure of right ventricular outflow tract tachycardia, and some forms of left ventricular tachycardia in patients with left ventricular dysfunction, has also been shown. In contrast limited data are available to assess the role of RF catheter ablation in treating idiopathic left ventricular tachycardia (ILVT), an unusual form of tachycardia occurring in patients without demonstrable heart disease.
Aim: To examine the efficacy and safety of RF catheter ablation in patients with ILVT.
Methods: Three patients without structural heart disease and with recurrent drug-refractory ILVT (right bundle branch block and left axis morphology) underwent electrophysiologic study (EPS) to initiate and localise the site of origin of their VT. RF catheter ablation of the VT focus was performed, with success being defined as failure to reinduce VT during incremental infusion of isoprenaline.
Results: In all three patients VT was inducible by rapid right atrial pacing and/or programmed ventricular stimulation, and could be terminated by intravenous verapamil. RF catheter ablation was successful in all patients. The site of successful ablation was common to each patient and was localised to the infero-apical aspect of the left ventricular septum. It was characterised by the recording of the earliest presystolic 'P' potential during both sinus rhythm and induced ILVT. No complications occurred during the procedure. During follow-up periods ranging from six to 12 months there were no symptomatic or documented episodes of recurrent ILVT.
Conclusions: We conclude that ILVT can be safely and effectively cured by RF catheter ablation.     

动态基质标测在致心律失常右室心肌病患者室性心动过速射频消融中的应用

目的　探讨应用非接触球囊导管标测系统行动态基质标测,指导对致心律失常右室心肌病(ARVC)患者室性心动过速(室速)消融的价值。方法　应用非接触球囊导管标测系统在窦律下对 3例ARVC室速患者行动态基质标测,在确定室速的最早激动点、出口部位和传导顺序后,寻找与室速相关的峡部并行线性消融。结果　3例患者存在 3种不同形态的基质,分别位于右室流出道、右室前壁和右室前侧壁。共诱发 5种室速,平均心动周期为(348±65)ms,其中 3种室速起源于基质或基质边缘, 2种室速的起源远离基质; 1种室速经基质传导。5种室速全部消融成功。平均随访 20个月,无心动过速发作。结论　应用非接触球囊导管标测系统确定异常电生理基质有助于理解ARVC室速的发生机制和制定消融策略,行室速相关峡部的线性消融可有效治疗室速。     

Mechanisms, prediction and treatment of ventricular tachyarrhythmias occurring late after myocardial infarction

Studies from the 1980s, refined in the intervening years, have examined the milieu for ventricular tachycardia (VT) and ventricular fibrillation (VF) occurring late after acute myocardial infarction (AMI). The arrhythmogenic substrate appears to be patchy areas of fibrous tissue interdigitating with viable bundles of myocardium which have distorted orientation and tortuous interconnections. These promote conduction delay in sinus rhythm. Factors found to promote induction of VT rather than VF are longer conduction delay in sinus rhythm, larger infarct size, a more ragged infarct edge and longer ventricular extrastimulus coupling intervals. Predictors of spontaneous VT and VF late after AMI include inducible VT at electrophysiological studies (EPS), delayed conduction in sinus rhythm detected as late potentials on signal-averaged surface electrocardiogram (ECG), and low left ventricular ejection fraction (LVEF). Treatments of propensity for VT or VF after AMI include insertion of a defibrillator (ICD), which has the best track record, antiarrhythmic medication (less reliable), and ablation or excision of arrhythmogenic substrate (for refractory VT and VF).     

Initial Clinical Experience with the New Irrigated Tip Magnetic Catheter for Ablation of Scar-Related Sustained Ventricular Tachycardia: A Small Case Series

Background: A remote magnetic navigation system (MNS) has been used with a nonirrigated magnetic catheter for ablation of some supraventricular and ventricular arrhythmias. However, the irrigated tip catheter has not been evaluated.
Objective: To evaluate the feasibility and efficiency of the newly available irrigated tip magnetic catheter for radiofrequency ablation (RF) of electrical storm due to scar-related ventricular tachycardia (VT) in patients with ischemic heart disease.
Methods: Between January and March 2008, a total of 4 consecutive patients (4 men, mean age 67.7 years) with electrical storm who had an implantable cardioverter defibrillator underwent radiofrequency ablation using a remote MNS and the new magnetic irrigated catheter.
Results: Five ablation procedures were performed in study patients. Acute success, defined as noninducibility of any monomorphic VT, was obtained in 3 patients. In 1 patient, a nonclinical VT remained inducible. A monomorphic VT corresponding to clinical VT with the median (range) cycle length of 485 (440–580) ms was induced in all patients. The duration of ablation was 2,273 (985–3087) seconds, with median total procedure and fluoroscopy times of 135 (100–150) minutes and 6.5 (5–9) minutes, respectively. One recurrence occurred 1 week after ablation, which was ablated successfully in the second session. No complication was observed after ablation. During mean follow-up of 4.2 months, all patients were in sinus rhythm, they received no ICD therapy, and no mortality occurred.
Conclusions: Irrigated ablation of scar-related ventricular tachycardia guided by remote MNS is a feasible and effective modality for management of the electrical storm in patients with ischemic cardiomyopathy with minimal radiation exposure.     

Does Electrogram Guided Substrate Ablation Add to the Success of Pulmonary Vein Isolation in Patients with Paroxysmal Atrial Fibrillation? A Prospective,Randomized Study

Introduction: Pulmonary vein isolation (PVI) is an established treatment for paroxysmal atrial fibrillation (AF). The ablation of complex fractionated atrial electrograms (CFAE) has emerged as a novel treatment approach. We sought to evaluate the additional effect of CFAE ablation to PVI in paroxysmal AF.
Methods and Results: Ninety-eight patients with paroxysmal AF (57 ± 10 years, 74 male) were randomized to the PVI (n = 48) or PVI + CFAE group (n = 50). After PVI, CFAE ablation was performed in patients with inducible AF in the PVI + CFAE group. The primary endpoint was combined objective (7-day Holter ECG) and subjective (symptoms) freedom of atrial tachyarrhythmia 3 months after ablation. Long-term follow-up (19 ± 8 months) was available in 94 of 98 patients. CFAE ablation was performed in 30 of 50 patients of the PVI + CFAE group. After 3 months, 36 of 48 patients (75%) in the PVI group and 38 of 50 patients (76%) in the PVI + CFAE group were in stable sinus rhythm (P = NS). During long-term follow-up (19 ± 8 months), 34 of 46 patients (74%) in the PVI group and 40 of 48 patients (83%) in the PVI + CFAE group were in sinus rhythm (P = 0.08). In a subgroup analysis, a significantly better long-term outcome was achieved if inducible AF after PVI had been treated by additional CFAE ablation as compared with PVI only (sinus rhythm in 25/28 patients; 89% vs 22/30 patients 73%; P = 0.003).
Conclusion: In the intention-to-treat analysis, additional CFAE ablation did not improve the success rate of PVI in patients with paroxysmal AF. However, during long-term follow-up, patients with still inducible AF after PVI seemed to profit from additional CFAE ablation.     

Ibutilide-Induced Changes in the Temporal Lability of Ventricular Repolarization in Patients with and without Structural Heart Disease

Introduction: Ibutilide has been shown to prolong repolarization times and increase the risk of ventricular tachyarrhythmias particularly in patients with structural heart disease. The mechanisms underlying its proarrhythmic effects remain incompletely understood. We sought to define the effects of ibutilide on the temporal lability of ventricular repolarization in patients with and without structural heart disease.
Methods: Twenty-four patients referred for electrophysiology study underwent monophasic action potential (MAP) recordings in the right ventricle during sinus rhythm and random interval right atrial pacing (RIAP). Ibutilide was subsequently administered and the recordings repeated both in sinus rhythm and with RIAP. Digitized recordings were analyzed offline for calculation of the QT variability index (QTVI) based on surface ECG, and the MAP duration variability index (MAPDVI) based on the intracardiac MAP signal.
Results: Of 24 patients enrolled, analyses were performed in 21 patients (mean age 59 ± 15 years, 38% women). In three patients, the data were not analyzed due to frequent premature ventricular complexes. Ibutilide resulted in significant changes in heart rate (mean difference: −7.4 ± 0.91 bpm, P < 0.0001) and the surface QT interval (mean difference: 59.6 ± 12.2 ms, P = 0.0001) during sinus rhythm. After ibutilide, QTVI remained unchanged from baseline during sinus rhythm but was significantly different in the setting of RIAP (mean difference: 0.345 ± 0.098, P = 0.0022). With subgroup analyses, these differences remained significant regardless of the presence or absence of heart disease.
Conclusion: Ibutilide results in overall prolongation of ventricular repolarization and reductions in baseline sinus rates. Ibutilide increases temporal lability of repolarization only with enriched fluctuations in heart rate.