Fascicular Ventricular Tachycardia Research Articles

Catheter ablation of ventricular tachycardia in the pediatric patients: A single-center experience.

Ventricular tachycardia (VT) with or without structural heart disease is uncommon but well-recognized clinically in children. With this retrospective study, we collected the data from the in-hospital pediatric patients of VT with catheter ablation therapy. The purpose of this study is to assess the acute results and the long-term outcome of catheter ablation in pediatric patients of VT in our single pediatric center. This study included 53 consecutive children (male/female=33/20, mean age=8.2±3.4 years, mean bodyweight=32.6±13.7kg). All patients underwent electrophysiological study with an attempt of catheter ablation for clinical monomorphic VT. Acute and long-term success rate of catheter ablation for the treatment of VT were compared between right and left VT as well as fascicular VT (FVT) and nonfascicular VT. There were 53 idiopathic VT forms found in the children, including FVT (n=32), outflow tract VT (n=15), papillary muscle VT (n=5), and bundle branch reentry VT (n=1). Acute success of catheter ablations for VT was achieved in 57 of all the 59 ablation procedures (97%) with VT recurrence occurred in six of 53 patients (11%). During a mean follow-up period of 29.2±21.7 months (range 1-76 months) after hospital discharge, ablations in nonfascicular VT were as successful as FVT. There was no significant difference in the success rate between the right and left VT. Catheter ablation is an effective treatment for idiopathic VT in children. The acute and long-term success rates of catheter ablation for idiopathic VT in pediatric patients with normal heart structure are satisfying.

Mapping and Ablation of Fascicular Tachycardias (Reentrant and Nonreentrant).

Fascicular ventricular tachycardia (FVT) usually involves the left fascicular system; namely the left posterior fascicle, anterior fascicle, and rarely the upper septal fascicle. It may also involve the right Purkinje arborization. This tachycardia can be seen in normal heart or in the setting of structural heart diseases. Monomorphic FVT can be reentrant or nonreentrant and verapamil-sensitive left FVT is the second most common type of idiopathic ventricular tachycardia (VT) after right ventricular outflow tract VT. This article focuses on the practical approach for both reentrant and nonreentrant FVT, explaining the mechanism, electrocardiographic features, and electrophysiologic features of FVT.

Coexisting fascicular ventricular tachycardia and papillary muscle ventricular tachycardia in the setting of coronary artery disease in a master athlete

A 73-year old male developed syncope during a bicycle race. Exercise stress testing demonstrated non-sustained ventricular tachycardia (NSVT) and ischemic changes. Coronary angiography revealed a 99% occluded right coronary artery which was stented; repeat stress testing demonstrated normal perfusion and NSVT. An electrophysiology study demonstrated left posterior fascicular ventricular tachycardia, which was ablated at two lower turnaround points. NSVT was observed during subsequent stress testing, prompting a repeat electrophysiology study. The inferoseptum and inferior wall were extensively ablated, along with a posteromedial papillary muscle premature ventricular complex. With no further demonstrable NSVT, the patient was cleared to return to competition.

Fascicular tachycardia in infancy and the use of verapamil: a case series and literature review

ObjectiveGuidelines state that verapamil is contraindicated in infants. This is based on reports of cardiovascular collapse and even death after rapid intravenous administration of verapamil in infants with supraventricular tachycardia...

Catheter ablation of left posterior fascicular ventricular tachycardia in children with limited fluoroscopy exposure

Catheter ablation of left posterior fascicular ventricular tachycardia in the pediatric population remains challenging, and most studies about this topic have been conducted on adult patients. This study aimed to assess the clinical presentation features and outcomes of catheter ablations performed using limited fluoroscopy with three-dimensional electroanatomic mapping system guidance in a pediatric left posterior fascicular ventricular tachycardia patient group. A total of 20 consecutive patients undergoing left posterior fascicular ventricular tachycardia ablation at a single tertiary centre were enrolled. All children with left posterior fascicular ventricular tachycardia underwent electrophysiological studies using the EnSite NavX system guidance. Ablations were performed during the sinus rhythm based on the Purkinje potentials in all patients. The mean patient age was 12.7 years (range 2-16), and the mean patient weight was 51 kg (range 11-84). The mean procedure and median fluoroscopy times were 143.1 minutes and 3.4 minutes, respectively. No fluoroscopy was used in three patients. Acute success was achieved in 19 patients (95%). During a mean follow-up of 38.6 ± 19.35 months, left posterior fascicular ventricular tachycardia recurred in four patients (20%). Repeat ablations were performed successfully in those patients who developed recurrences. No complications were seen. Catheter ablation of left posterior fascicular ventricular tachycardia in children can be performed safely and effectively with low fluoroscopy exposure using a three-dimensional electroanatomic mapping system.

New implications for the recurrence mechanism of an upper septal ventricular tachycardia: a case report.

BackgroundVerapamil-sensitive fascicular ventricular tachycardia (VT) is the most common type of idiopathic left ventricular tachycardia, and it is divided into three types. Upper septal ventricular tachycardia (US-VT) is likely in patients with prior episodes of left posterior fascicular (LPF)-VT ablation, however, little is known about the recurrence mechanism of US-VT.Case summaryA 53-year-old man had an US-VT after two catheter ablation sessions for a common idiopathic LPF-VT. The US-VT was successfully treated by ablating the proximal site of the LPF without making any further branch or fascicular block. This successful ablation point corresponded completely with the earliest pre-systolic potential (P2) site of the LPF-VT during the 1st session of catheter ablation.DiscussionAn US-VT recurrence could occur if a critical slow conduction is not affected by the catheter ablation. This recurrence might be the result of changing the re-entrant circuit after damage to the LPF. In order to eliminate the LPF-VT and prevent an US-VT recurrence, the earliest P2 site should be investigated carefully and ablated sufficiently.

Uncommon cause of wide complex tachycardia - Anterior fascicular ventricular tachycardia

A 24-year-old female presented to the emergency room with sudden-onset palpitations and shortness of breath for 4 h. We report a rare cause of anterior fascicular ventricular tachycardia.

Catheter ablation for fascicular ventricular tachycardia: A systematic review

IntroductionCatheter ablation has been evaluated as treatment for fascicular ventricular tachycardia (FVT) in several single-centre cohort studies, with variable results regarding efficacy and outcomes. MethodsA systematic search was performed on PubMed, EMBASE and Cochrane database (from inception to November 2017) that included studies on FVT catheter ablation. ResultsThirty-eight observational non-controlled case series comprising 953 patients with FVT undergoing catheter ablation were identified. Three studies were prospective and only 5 were multi-centre. Eight-hundred and eighty-four patients (94.2%) had left posterior FVT, 25 (3.4%) left anterior FVT and 30 (2.4%) other forms. In 331 patients (41%), ablation was performed in sinus rhythm (SR). The mean follow-up period was 41.4 ± 10.7 months. Relapse of FVT occurred in 100 patients (10.7%). Among the 79 patients (8.3%) requiring a further procedure after the index ablation, 19 (2%) had further FVT relapses. Studies in which ablation was performed in FVT had similar success rate after multiple procedures compared to ablation in SR only (95.1%, CI95% 92.2–97%, I2 = 0% versus 94.8%, CI95% 87.6–97.9%, I2 = 0%, respectively). Success rate was numerically lower in paediatric-only series compared to non-paediatric cases (90.0%, CI95% 82.1–94.6%, I2 = 0% versus 94.3%, CI95% 92.2–95.9%, I2 = 0%, respectively). ConclusionData derived from observational non-controlled case series, with low-methodological quality, suggest that catheter ablation is a safe and effective treatment for FVT, with a 93.5% success rate after multiple procedures. Ablation during FVT represents the first-line and most commonly used approach; however, a strategy of mapping and ablation during SR displayed comparable procedural results to actively mapping patients in FVT and should therefore be considered in selected cases where FVT is not inducible.

The prevalence and characteristics of coexisted atrioventricular nodal reentrant tachycardia and idiopathic left fascicular ventricular tachycardia.

Coexistence of idiopathic left fascicular ventricular tachycardia (ILFVT) and atrioventricular nodal reentrant tachycardia (AVNRT) has been rarely reported. The study aimed at elucidating the prevalence of coexisted AVNRT in patients with ILFVT during longitudinal follow-up. The electrophysiological properties and clinical predictors of coexisted ILFVT and AVNRT were investigated. From 1999 to 2017, a total of 108 patients (age: 33.7 ± 14.3, 84 male) with ILFVT from one tertiary center were consecutively enrolled. The prevalence of coexisted arrhythmias was explored during a longitudinal follow-up and the electrophysiological parameters from the index procedure were compared. During a mean follow-up period of 106.8 ± 69.5 months, 21 of 108 patients (19.4%) had coexisted AVNRT. The electrophysiological study demonstrated patients with coexisted ILFVT and AVNRT were characterized by more antegrade dual AV node conduction (52.4%vs. 19.5%, P=0.002; 9.5%), shorter antegrade slow pathway effective refractory period (285.1 ± 34.1ms vs. 329.2 ± 69.2ms, P=0.034), longer retrograde fast pathway effective refractory period (368.9 ± 56.7ms vs. 312.5 ± 95.2, P=0.036), and less VA dissociation (19.0%vs. 60.9%, P=0.001) than those without a coexisted AVNRT. Multivariate logistic analysis showed that presence of antegrade dual AV nodal physiology and retrograde VA conduction could predict a coexisted AVNRT in patients with ILFVT (P=0.005, OR: 4.80, 95% CI: 1.65-14.37 and P=0.002, OR: 0.14, 95% CI: 0.04-0.49, respectively). There was a high prevalence of coexisted AVNRT in patients with ILFVT during longitudinal follow-up. The presence of antegrade dual AV nodal physiology and retrograde VA conduction can predict the coexisted AVNRT in patients with ILFVT.

Alternans during fascicular ventricular tachycardia due to digitalis toxicity

This report describes a digitalis-induced regular fascicular ventricular tachycardia characterized by marked QRS alternans a manifestation not usually associated with this arrhythmia. The striking alternation of QRS configuration suggested alternating ventricular activation from either a single focus with two exits in distal branches of the left anterior fascicle or 2 different foci localized in the Purkinje-myocardial network of the left anterior fascicle.

Tachycardia-induced Cardiomyopathy in a Teenage Boy

Tachycardiomyopathy or tachycardia-induced cardiomyopathy (TIC) is a relatively rare but completely or partially treatable condition, where there is an impairment of left ventricular (LV) function secondary to chronic, continuous, or intermittent tachycardia, which presents as heart failure. It has been shown that the rate control by means such as cardioversion, negative chronotropic agents, and surgical- or catheter-based atrioventricular nodal ablation, depending on the etiology, resulted in significant improvement of systolic function. The diagnosis of TIC is entertained following the observation of improvement in LV systolic function, after necessary therapy to control the arrhythmia or heart rate. It is necessary that the clinicians should have a high index of suspicion while dealing with LV systolic dysfunction or dilated cardiomyopathy and should control the arrhythmia stringently. This case report describes a 14-year-old boy presenting with breathlessness of 18–24-month duration who had features of dilated cardiomyopathy on echocardiography. Impaired LV systolic function was due to fascicular ventricular tachycardia and he recovered completely after catheter-based ablation within a period of 5–6 months.

Apical Variant of Hypertrophic Cardiomyopathy Presenting as Recurrent Syncope and Wide Complex Tachycardia

Apical hypertrophic cardiomyopathy (AHC) is an uncommon variant of hypertrophic cardiomyopathy usually found as an incidental finding during routine echocardiography. It was first described by Sakamoto in 1976 in Japanese patients. Echocardiography is still considered as the best screening tool to assess AHC although MRI is considered as the gold standard for confirmation. In this case, we present a 21-year-old man with AHC who presented with recurrent brief syncopal episodes which were ignored by the patient until he was brought to us with prolonged syncope and wide complex tachycardia/ posterior fascicular ventricular tachycardia. We observed the classical findings in the plain twelve lead electrocardiograms done after cardioversion. It is always wise to keep special attention to evaluate hypertrophic cardiomyopathy (HCM) in young patients presenting with syncope.Journal of Advances in Internal Medicine 2017;06(02):32-34.

In This Issue: November

In This Issue: November

Catheter Ablation of Idiopathic Left Posterior Fascicular Ventricular Tachycardia: Predicting the Site of Origin via Mapping and Electrocardiography.

We report the 12-lead ECG morphology of left posterior fascicular ventricular tachycardia (LPF-VT) and the relationship between His-ventricular (HV) interval and site of origin in LPF-VT. We studied 41 patients who underwent successful catheter ablation of LPF-VT with HV interval >0 ms (n=8; proximal-LPF group), HV interval 0 to -15 ms (n=15; middle-LPF group), and HV interval <-15 ms (n=18; distal-LPF group). The earliest mapped presystolic potential (PP)-QRS interval was 34.1±4.2, 24.5±3.2, and 19.4±2.8 ms in proximal-, middle-, and distal-LPF groups. The earliest PP ratio (PP-QRS interval during VT/HV interval during sinus rhythm) was 0.59±0.05, 0.45±0.07, and 0.31±0.05 in the proximal-, middle-, and distal-LPF groups. There were statistically significant differences between the 3 groups in earliest PP ratio, and there was close correlation between the HV interval during LPF-VT and earliest PP ratio. The QRS duration in the proximal-LPF group (114±6 ms) was significantly narrower compared with the middle-LPF group (128±5 ms) and distal-LPF group (140±6 ms). In leads I and V6, the ratio of R/S tended to be greater in the proximal-LPF group compared with the other 2 groups. QRS duration, the ratio of R/S in leads V6, and lead I could predict a proximal or distal origin site of LPF-VT with high sensitivity and specificity. The HV interval and 12-lead ECG morphology of LPF-VT may help predict the successful site of origin and prove useful in guiding an effective ablation strategy.

Fascicular Tachycardia: The Great Masquerader

SESSION TITLE: Cardiovascular Disease SESSION TYPE: Affiliate Case Report Poster PRESENTED ON: Tuesday, October 31, 2017 at 01:30 PM - 02:30 PM INTRODUCTION: Hemodynamically stable tachycardia in a young seemingly healthy individual is generally assumed to be supraventricular in origin. However there is a type of ventricular tachycardia (VT) that has a relatively narrow complex that presents in young healthy individuals and is frequently misdiagnosed as supraventricular ventricular tachycardia (SVT). We present such a case and demonstrate the consequence of delayed diagnosis. CASE PRESENTATION: Our case is a 39 year old male with no past medical history who presented to our emergency department with one day of palpitations and diaphoresis. He first noted these symptoms in adolescence, which were of shorter duration and therefore medical attention was never sought. On arrival to our institution the patient was hemodynamically stable on presentation with an unremarkable physical exam other than a pulse rate of 200 bpm with an EKG showing wide complex tachycardia (figure 1). In addition his blood chemistries were all within normal limits. Despite receiving multiple rounds of adenosine (6mg, 12mg, 12mg) followed by electrical cardioversion, patient remained in wide complex tachycardia. Patient was then given Diltiazem 20mg IVP, which resulted in conversion to normal sinus rhythm (figure 2). Closer investigation of the presenting ECG revealed a leftward (northwest) axis and an incomplete RBBB pattern with RSR’ complexes, a finding highly specific for ventricular tachycardia (VT). An Echocardiogram at our institution revealed no structural heart disease with normal ventricular systolic function. Patient was taken for further electrophysiological testing which confirmed Left Fascicular VT. Patient underwent radiofrequency catheter ablation without any complications. DISCUSSION: Fascicular tachycardia typically originates in the region of the left posterior fascicle and has a RBBB, left superior axis morphology and AV disassociation. In most, a resting EKG is normal and there is no evidence of structural heart disease evidenced by echocardiography and coronary angiography. The narrow QRS complex (typically 0.12 to 0.14 sec) morphology distinguishes fascicular VT from most VTs, but it also resembles SVT frequently leading to misdiagnosis. CONCLUSIONS: Our goal is to help clinicians, especially those who first encounter patients’ with this presentation, be cognizant about the subtle important features of fascicular tachycardia. When it comes to wide complex tachyarrhythmias’ clinicians often have a sense of uneasiness, further clouding their clinical judgment. It is therefore imperative to recognize cases of Idiopathic VT, precisely fascicular tachycardia so they can be differentiated from svt and treated appropriately. Reference #1: Brooks R, Burgess JH. Idiopathic ventricular tachycardia. A review. Medicine (Baltimore) 1988; 67:271. Reference #2: Belhassen B, Viskin S. Idiopathic ventricular tachycardia and fibrillation. J Cardiovasc Electrophysiol 1993; 4:356. DISCLOSURE: The following authors have nothing to disclose: Shahab Khan, Ravi Mann, Fawzi Ameer, David Slotwiner No Product/Research Disclosure Information

Differentiating the QRS Morphology of Posterior Fascicular Ventricular Tachycardia From Right Bundle Branch Block and Left Anterior Hemiblock Aberrancy.

Left posterior fascicular ventricular tachycardia (LPF-VT) is frequently misdiagnosed as supraventricular tachycardia with aberrant right bundle branch block (RBBB) and left anterior hemiblock (LAHB). The purpose of the present study was to define the morphological ECG characteristics of LPF-VT and attempt to differentiate it from RBBB and LAHB aberrancy. A systematic Medline search was used to identify or locate ECG tracings from patients with LPF-VTs. ECGs with LPF-VT were also collected from patients who underwent ablation of this arrhythmia at the Tel Aviv and Sheba Medical Centers. These ECGs were compared with ECGs of consecutive patients with RBBB and LAHB and no obvious cardiac pathology by echocardiography. Overall, 183 ECGs of LPF-VT were compared with 61 ECGs showing RBBB and LAHB. Univariate analysis demonstrated differences in QRS axis, limb (I, aVr), and precordial (V1, V2, V6) ECG leads. On multivariate logistic regression analysis, LPF-VT was more often associated with atypical RBBB-like V1 morphology (odds ratio, 5.1; P=0.004), positive QRS in aVr (odds ratio, 19.2; P<0.001), V6 R/S ratio ≤1 (odds ratio, 6.7; P=0.01), and QRS ≤140 ms (odds ratio, 7.7; P<0.001). Using these 4 variables, a prediction model was developed that predicted LPF-VT with sensitivity and specificity of 82.1% and 78.3%, respectively. Patients with 3 of 4 positive variables had high probability of having LPF-VT, whereas patients with ≤1 positive variable always had RBBB plus LAHB. The morphological ECG characteristics of LPF-VT were defined, and a high accurate tool for correctly differentiating LPF-VT from RBBB and LAHB aberrancy was developed.

Long-term outcome of catheter ablation for left posterior fascicular ventricular tachycardia with the development of left posterior fascicular block and characteristics of repeat procedures

ObjectiveThe present study aimed to retrospectively investigate long-term clinical outcomes of patients undergoing catheter ablation of left posterior fascicular ventricular tachycardia (LPF-VT) with the development of left posterior fascicular block (LPF block) and characteristics of repeat procedures. Methods and resultsA total of 195 patients (mean age 29.76±1.03years, 16.4% females) who underwent catheter ablation for LPF-VT were consecutively enrolled. The earliest ventricular potential with a single fused Purkinje potential (PP) during VT and the PP located in the inferior-apical or mid-apical septum during SR were targeted for linear ablation. The endpoint of the procedure was noninducible VT and development of new-onset LPF block. Follow-up with clinic visits or telephonic interviews, electrocardiogram (ECG), or Holter monitoring was performed after the procedure. With a median follow-up of 85 (18,181) months, 20 patients were censored and 152 of 175 (86.86%) patients had long-term freedom from VT after a single procedure. No statistical difference in the outcome of catheter ablation of LPF-VT was found between inducible and non-inducible groups (P=0.89). Twenty-three patients exhibited recurrent LPF-VT. Seven of 23 patients developed new-onset left upper septal ventricular tachycardia that was successfully ablated. All the patients undergoing repeat procedures had freedom from VT. No procedural complications occurred. ConclusionsAblation of LPF-VT using the development of LPF block as the endpoint is associated with a high procedural success rate. No difference in freedom from LPF-VT was found between inducible and non-inducible patients. New-onset LPF block recovery and non-early PP-QRS interval can be the predictors of LPF-VT repeat procedure.

Clinical, electrocardiographic, and electrophysiological characteristics of left upper septal fascicular ventricular tachycardia

We sought to investigate the clinical, electrocardiographic, and electrophysiological characteristics of left upper septal fascicular ventricular tachycardia (LUS-VT). Eleven consecutive patients with LUS-VT were identified among 196 patients with left fascicular ventricular tachycardia (VT). Clinical VTs presented as paroxysmal in 8 patients and incessant in 3 patients. Six patients had previous left posterior fascicular VT ablation history. All VTs had narrow QRS complexes with QRS duration of 101.1 ± 9.2 ms. The frontal QRS axis was normal or right deviation. Precordial morphology was either right bundle branch block type or similar to that of sinus rhythm. A retrograde His with H-V interval of 21.9 ± 7.2 ms was recorded during VT. The earliest Purkinje potential (PP) to QRS interval during VT averaged 35.7 ± 4.5 ms. Clear diastolic potentials (DPs) with high frequency and low amplitude were found in only one patient. Ten patients were managed successfully by 11 ablation sessions, and 1 patient declined ablation. Successful targets at the left upper septum were sites with the earliest PP (9 cases) or with DP (1 case) during VT. After ablation, 2 cases (10%) developed new left anterior hemiblock or incomplete left bundle branch block. No VT recurred during a median follow-up period of 3.2 (range 1.0-12.7) years. LUS-VT presented as narrow QRS complex tachycardia. Some LUS-VTs occurred after ablation targeting left posterior fascicular VT. The VTs can be managed successfully by focal ablation at the left upper septum with a mild risk of fascicular injury.

Fascicular Ventricular Arrhythmias: Pathophysiologic Mechanisms, Anatomical Constructs, and Advances in Approaches to Management.

Ventricular arrhythmias involving the fascicular system may be seen in both structurally normal and abnormal hearts. Idiopathic fascicular ventricular tachycardia represents almost 10% to 15% of idiopathic ventricular tachycardia related to the left ventricle.1,2 Cohen et al3 and subsequently Zipes et al4 first described these arrhythmias in the 1970s as relatively narrow right bundle left axis arrhythmias that arose close to the posterior fascicle and could be induced with atrial pacing. Belhassen et al5 later described the responsiveness of these arrhythmias to verapamil. Although initial studies focused on arrhythmias related to the left posterior fascicle, it is possible for arrhythmias to arise from any portion of the fascicular system and in both structurally normal and abnormal hearts. Furthermore, when approaching the patient presenting with arrhythmias arising from the His-Purkinje system, it is important to consider the unique complexities related to mapping and ablation. In this review, we will focus on the mechanisms of such arrhythmias, relevant embryology, anatomy and physiology, and approaches to management in both the presence and absence of other structural heart disease. Broadly, fascicular ventricular tachycardia in the absence of other structural heart disease will be termed idiopathic fascicular ventricular tachycardia (IFVT), whereas that related to structural disease will be discussed in the context of the relevant disease state. Generally, IFVT is separated into 3 types—left posterior fascicular with a right bundle branch block pattern and left axis deviation, left anterior with a right bundle branch block and right axis deviation pattern, and left upper septal fascicular with a narrow QRS and normal axis but often with a right bundle branch block morphology. There are rare reported cases of left bundle branch block pattern, V3–V4 transition IFVT with a normal axis arising from the right bundle branch. In …

Special electrophysiological characteristics of pediatric idiopathic ventricular tachycardia

BackgroundIdiopathic ventricular tachycardia (VT) is an important pediatric arrhythmia but relevant studies in Asian cohort are rare. We determined the electrophysiological characteristics and outcomes of this rhythm disturbance. MethodsFrom an institutional database, patients aged <18years without structural heart disease who have sustained monomorphic VT (longer than 30s) during 1995–2016 were enrolled. ResultsWe enrolled 57 idiopathic VT patients (male:female=31:26). The initial presentation included palpitation (64.9%) and shock (12.3%). The electrocardiography revealed relatively short QRS duration (123±18ms) and absence of ventriculoatrial dissociation in 33.3% of the patients, causing initial misdiagnosis in 29.8% of these patients. Patients with a VT onset age of <10years were more likely to have a left bundle branch block morphology (52.2% vs. 11.8%, p=0.001) and spontaneous recovery than those with a VT onset age of ≥10years. An electrophysiology study in 44 patients revealed that the most common arrhythmia focus was the left ventricular septal area (78%), called fascicular VT. Radiofrequency ablation showed a satisfactory success rate (90%) and fair recurrence rate (14.3%). Tachycardia-induced cardiomyopathy was noted in 14% of the VT patients and cardiac function returned to normal in 1–18months (median, 3months) after successful ablation. ConclusionsIn an Asian pediatric population, VT has distinct electrophysiological characteristics including dominant left ventricular origin, narrower QRS duration, and more symptomatic presentation. Transcatheter ablation is effective against VT, and the associated cardiomyopathy often resolves rapidly after successful ablation.