Exploring postinfarction reentrant ventricular tachycardia with entrainment mapping

Impact of a high-density grid catheter on long-term outcomes for structural heart disease ventricular tachycardia ablation

Background

Substrate mapping has highlighted the importance of targeting diastolic conduction channels and late potentials during ventricular tachycardia (VT) ablation. State-of-the-art multipolar mapping catheters have enhanced mapping capabilities. The purpose of this study was to investigate whether long-term outcomes were improved with the use of a HD Grid mapping catheter combining complementary mapping strategies in patients with structural heart disease VT.

Methods

Consecutive patients underwent VT ablation assigned to either HD Grid, Pentaray, Duodeca, or point-by-point (PbyP) RF mapping catheters. Clinical endpoints included recurrent anti-tachycardia pacing (ATP), appropriate shock, asymptomatic non-sustained VT, or all-cause death.

Results

Seventy-three procedures were performed (33 HD Grid, 22 Pentaray, 12 Duodeca, and 6 PbyP) with no significant difference in baseline characteristics. Substrate mapping was performed in 97% of cases. Activation maps were generated in 82% of HD Grid cases (Pentaray 64%; Duodeca 92%; PbyP 33% (p = 0.025)) with similar trends in entrainment and pace mapping. Elimination of all VTs occurred in 79% of HD Grid cases (Pentaray 55%; Duodeca 83%; PbyP 33% (p = 0.04)). With a mean follow-up of 372 ± 234 days, freedom from recurrent ATP and shock was 97% and 100% respectively in the HD Grid group (Pentaray 64%, 82%; Duodeca 58%, 83%; PbyP 33%, 33% (log rank p = 0.0042, p = 0.0002)).

Conclusions

This study highlights a step-wise improvement in survival free from ICD therapies as the density of mapping capability increases. By using a high-density mapping catheter and combining complementary mapping strategies in a strict procedural workflow, long-term clinical outcomes are improved.

CT- und MRT-Bildgebung in der Rhythmologie

Die Anwendung bildgebender Verfahren gewinnt in der interventionellen Elektrophysiologie entgegen der geringen Beachtung in den aktuell geltenden nationalen und internationalen Leitlinien zur Behandlung von Patienten mit Vorhofflimmern und ventrikulären Tachykardien auch über die reine Diagnostik zugrunde liegender struktureller Herzerkrankungen hinaus immer mehr an Bedeutung. Die breite Anwendung der Computertomografie (CT) und der Magnetresonanztomografie (MRT) ergibt sich aus den spezifischen Möglichkeiten dieser bildgebenden Techniken heraus: Gewebecharakterisierung des Myokards auf Vorhof- und Kammerebene mit präziser Darstellung von Infarktnarben, Grenzzonen und vitalem Myokard (MRT inklusive Late-Gadolinium-Enhancement-Darstellung); hochauflösende Darstellung wichtiger anatomischer Strukturen inklusive der Koronararterien und präzise Identifizierung von kritischer ventrikulärer Wandausdünnung im Infarktareal (CT); Identifizierung potenzieller Komplikationen nach Vorhofflimmerablation (Pulmonalvenenstenosen, Ösophagusruptur oder -fistel). Stärken und Schwächen sowie mögliche relative und absolute Kontraindikationen bei der Anwendung dieser beiden Methoden müssen jedoch berücksichtigt werden. Generell kann die Anwendung bildgebender Verfahren insbesondere für die Therapieplanung und -steuerung als wertvolle Ergänzung mit der Möglichkeit der Steigerung von Effektivität und Sicherheit gesehen werden. Prospektive randomisierte Studien liegen jedoch zu wichtigen aktuellen Anwendungsbereichen der CT und MRT noch nicht vor. Wichtigste Grundlage der interventionellen Elektrophysiologie in der Therapie supraventrikulärer und ventrikulärer Arrhythmien wird noch auf lange Sicht die Anwendung klassischer elektrophysiologischer Manöver und Strategien sowie die Verwendung sich immer weiter entwickelnder elektroanatomischer Mappingsysteme bleiben.

2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.

2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.

Multicenter Study of Dynamic High-Density Functional Substrate Mapping Improves Identification of Substrate Targets for Ischemic Ventricular Tachycardia Ablation

OBJECTIVES

The goal of this study was to evaluate the role of dynamic substrate changes in facilitating conduction delay and re-entry in ventricular tachycardia (VT) circuits.

BACKGROUND

The presence of dynamic substrate changes facilitate functional block and re-entry in VT but are rarely studied as part of clinical VT mapping.

METHODS

Thirty patients (age 67 ± 9 years; 27 male subjects) underwent ablation. Mapping was performed with the Advisor HD Grid multipolar catheter. A bipolar voltage map was obtained during sinus rhythm (SR) and right ventricular sense protocol (SP) single extra pacing. SR and SP maps of late potentials (LP) and local abnormal ventricular activity (LAVA) were made and compared with critical sites for ablation, defined as sites of best entrainment or pace mapping. Ablation was then performed to critical sites, and LP/LAVA identified by the SP.

RESULTS

At a median follow-up of 12 months, 90% of patients were free from antitachycardia pacing (ATP) or implantable cardioverter-defibrillator shocks. SP pacing resulted in a larger area of LP identified for ablation (19.3 mm² vs. 6.4 mm²) during SR mapping (p = 0.001), with a sensitivity of 87% and a specificity of 96%, compared with 78% and 65%, respectively, in SR.

CONCLUSIONS

LP and LAVA observed during the SP were able to identify regions critical for ablation in VT with a greater accuracy than SR mapping. This may improve substrate characterization in VT ablation. The combination of ablation to critical sites and SP-derived LP/LAVA requires further assessment in a randomized comparator study.

Epicardial Ablation in Nonischemic Ventricular Tachyardia

In patients with nonischemic cardiomyopathy, epicardial ablation is critical in targeting epicardial paravalvular substrate. Epicardial access and ablation can be performed safely with attention to epicardial structures, such as the coronary arteries, phrenic nerve, and epicardial fat. This review explores the indications, techniques, complications, and outcomes of epicardial ablation in patients with nonischemic cardiomyopathy. Although epicardial ablation adds to the complexity and risk of the ablation procedure, it is a vital tool that, combined with endocardial mapping and ablation, improves outcomes in patients with nonischemic cardiomyopathy suffering from ventricular arrhythmias.

Left-lateral thoracotomy for catheter ablation of scar-related ventricular tachycardia in patients with inaccessible pericardial access

Objectives

We aimed to describe the feasibility of a surgical left thoracotomy for catheter ablation of scar-related ventricular tachycardia (VT) in patients with inaccessible pericardial access.

Background

Pericardial adhesion due to prior cardiac surgery or previous epicardial ablation procedures limits epicardial access in patients with drug-refractory VT originated from the epicardium.

Methods

Six patients who underwent a surgical left lateral thoracotomy epicardial access for catheter ablation of VT after failed subxiphoid percutaneous epicardial access were reviewed. Patients’ baseline characteristics and procedural characteristics including epicardial access, mapping, and ablation were described. Epicardial access was successfully obtained in all patients by a surgical left lateral thoracotomy.

Results

The reasons of pericardial adhesion were prior cardiac surgery (n = 3, 50%) and previous epicardial ablation procedures (n = 3, 50%). Epicardial mapping of the lateral and inferior left ventricle was acquired, and a total of 15 different VTs originated from those regions were abolished. Unless one patient with ST elevation myocardial infarction due to periprocedural occlusion of the posterior descending artery no further complications occurred. All patients were discharged 10.2 ± 4 days after the procedure. VT recurred in 1 patient (17%) and was controlled with oral amiodarone therapy during follow-up (median follow-up: 479 days).

Conclusions

A surgical left lateral thoracotomy is feasible and safe for selected patients. This approach provides epicardial ablation in patients with VT located at the infero-lateral left ventricle and pericardial adhesions due to previous cardiac surgery or previous ablation procedures.

Graphic abstract

Myocardial fibrosis and the effect of primary prophylactic defibrillator implantation in patients with non-ischemic systolic heart failure-DANISH-MRI

AIMS

Patients with non-ischemic systolic heart failure have an increased risk of sudden cardiac death (SCD). Myocardial fibrosis, detected as late gadolinium enhancement (LGE) with cardiac magnetic resonance (CMR), has been shown to predict all-cause mortality. We hypothesized that LGE can identify patients with non-ischemic heart failure who will benefit from ICD implantation.

METHODS AND RESULTS

In this prospective observational sub-study of the Danish Study to Assess the Efficacy of ICDs in Patients with Nonischemic Systolic Heart Failure on Mortality (DANISH), 252 patients underwent CMR. LGE was quantified by the full width/half maximum method. The primary endpoint was all-cause mortality. LGE could be adequately assessed in 236 patients, median age was 61 years and median duration of heart failure was 14 months; there were 108 patients (46%) randomized to ICD. Median follow-up time was 5.3 years. Median left ventricular ejection fraction on CMR was 35%. In all, 50 patients died. LGE was present in 113 patients (48%). The presence of LGE was an independent predictor of all-cause mortality (HR 1.82; 95% CI 1.002-3.29; P = .049) after adjusting for known cardiovascular risk factors. ICD implantation did not impact all-cause mortality, for either patients with LGE (HR 1.18; 95% CI 0.59-2.38; P = .63), or for patients without LGE (HR 1.00; 95% CI 0.39-2.53; P = .99), (P for interaction =0.79).

CONCLUSION

In patients with non-ischemic systolic heart failure, LGE predicted all-cause mortality. However, in this cohort, LGE did not identify a group of patients who survived longer by receiving an ICD.

An efficient algorithm based on electrograms characteristics to identify ventricular tachycardia isthmus entrance in post-infarct patients

AIMS

Our study assesses the value of electrograms (EGMs) characteristics to identify a ventricular tachycardia (VT) isthmus entrance in patients with post-infarct VT. Post-infarct VTs are mostly due to a re-entrant circuit. A pacemapping (PM) approach is able to localize the VT isthmus during sinus rhythm. Limited data are available about the role of local EGMs in defining VT isthmus location.

METHODS AND RESULTS

Twenty consecutive patients (70% male) referred for post-infarct VT catheter ablation were included in the present study. The VT isthmus was defined according to the PM method. At each recording site, 10 characteristics of the local EGM were assessed to predict the location of the VT isthmus entrance. In total, 924 EGMs were acquired, of which 127 were located in the VT isthmus entrance. Logistic regression analysis showed that bipolar voltage, number of EGM positive peaks, and sQRS interval were independently associated with VT isthmus entrance location. The ROC curve best fitted the model at the cut-off 0.1641 (sensitivity 72%, specificity 75.2%, positive predictive value 31.3%, negative predictive value 94.4%, area under the curve 0.78, P < 0.001). Based upon these results, we developed an algorithm implemented in an automatic calculator to determine the likelihood that an EGM is located at a VT isthmus entrance.

CONCLUSION

Our study suggests that three EGM characteristics: bipolar voltage, number of positive peaks, and sQRS interval can successfully identify a VT isthmus entrance in post-infarct patients.

Focal Ventricular Tachycardias in Structural Heart Disease: Prevalence, Characteristics, and Clinical Outcomes After Catheter Ablation

OBJECTIVES

This study sought to summarize the procedural characteristics and outcomes of patients with structural heart disease (SHD) who have focal ventricular tachycardia (VT).

BACKGROUND

Scar-mediated re-entry is the predominant mechanism of VT in SHD. Some SHD patients may have a focal VT mechanism that remains poorly described.

METHODS

An extended induction protocol incorporating programmed electrical stimulation, right ventricular burst pacing and isoprenaline was used to elucidate both re-entrant and focal VT mechanisms.

RESULTS

Eighteen of 112 patients (16%) with SHD undergoing VT ablation over 2 years had a focal VT mechanism elucidated (mean age 66±13 years; ejection fraction 46±14%; nonischemic cardiomyopathy 10). Repetitive failure of termination with antitachycardia pacing (ATP) (69% of patients) or defibrillator shocks (56%) was a common feature of focal VTs. A median of 3 VTs per patient were inducible (28 focal VTs, 34 re-entrant VTs; 53% of patients had both focal and re-entrant VT mechanism). Focal VTs more commonly originated from the right ventricle (RV) than the left ventricle (LV) (67% vs. 33%, respectively). In the RV, the RV outflow tract was the most common site (33% of all focal VTs), followed by the RV moderator band (22%), apical septal RV (6%), and lateral tricuspid annulus (6%). The lateral LV (non-Purkinje) was the most common LV focal VT site (16%), followed by the papillary muscles (17%). After median follow-up of 289 days, 78% of patients remained arrhythmia-free; no patients had recurrence of focal VT at repeat procedure. In patients with recurrence, defibrillator therapies were significantly reduced from a median of 53 ATP episodes pre-ablation to 10 ATP episodes post-ablation. During follow-up, 2 patients (11%) underwent repeat VT ablation; none had recurrence of focal VT.

CONCLUSIONS

Focal VTs are common in patients with SHD and often coexist with re-entrant forms of VT. High failure rate of defibrillator therapies was a common feature of focal VT mechanisms. Uncovering and abolishing focal VT may further improve outcomes of catheter ablation in SHD.

Targeted Ablation of Ventricular Tachycardia Guided by Wavefront Discontinuities During Sinus Rhythm

Background:

Accurate and expedited identification of scar regions most prone to reentry is needed to guide ventricular tachycardia (VT) ablation. We aimed to prospectively assess outcomes of VT ablation guided primarily by the targeting of deceleration zones (DZ) identified by propagational analysis of ventricular activation during sinus rhythm.

Methods:

Patients with scar-related VT were prospectively enrolled in the University of Chicago VT Ablation Registry between 2016 and 2018. Isochronal late activation maps annotated to the latest local electrogram deflection were created with high-density multielectrode mapping catheters. Targeted ablation of DZ (>3 isochrones within 1cm radius) was performed, prioritizing later activated regions with maximal isochronal crowding. When possible, activation mapping of VT was performed, and successful ablation sites were compared with DZ locations for mechanistic correlation. Patients were prospectively followed for VT recurrence and mortality.

Results:

One hundred twenty patients (median age 65 years [59-71], 15% female, 50% nonischemic, median ejection fraction 31%) underwent 144 ablation procedures for scar-related VT. 57% of patients had previous ablation and epicardial access was employed in 59% of cases. High-density mapping during baseline rhythm was performed (2518 points [1615-3752] endocardial, 5049±2580 points epicardial) and identified an average of 2±1 DZ, which colocalized to successful termination sites in 95% of cases. The median total radiofrequency application duration was 29 min (21-38 min) to target DZ, representing ablation of 18% of the low-voltage area. At 12±10 months, 70% freedom from VT recurrence (80% in ischemic cardiomyopathy and 63% in nonischemic cardiomyopathy) was achieved. The overall survival rate was 87%.

Conclusions:

A novel voltage-independent high-density mapping display can identify the functional substrate for VT during sinus rhythm and guide targeted ablation, obviating the need for extensive radiofrequency delivery. Regions with isochronal crowding during the baseline rhythm were predictive of VT termination sites, providing mechanistic evidence that deceleration zones are highly arrhythmogenic, functioning as niduses for reentry.

Cardiac arrhythmias in the emergency settings of acute coronary syndrome and revascularization: an European Heart Rhythm Association (EHRA) consensus document, endorsed by the European Association of Percutaneous Cardiovascular Interventions (EAPCI), and European Acute Cardiovascular Care Association (ACCA)

Despite major therapeutic advances over the last decades, complex supraventricular and ventricular arrhythmias (VAs), particularly in the emergency setting or during revascularization for acute myocardial infarction (AMI), remain an important clinical problem. Although the incidence of VAs has declined in the hospital phase of acute coronary syndromes (ACS), mainly due to prompt revascularization and optimal medical therapy, still up to 6% patients with ACS develop ventricular tachycardia and/or ventricular fibrillation within the first hours of ACS symptoms. Despite sustained VAs being perceived predictors of worse in-hospital outcomes, specific associations between the type of VAs, arrhythmia timing, applied treatment strategies and long-term prognosis in AMI are vague. Atrial fibrillation (AF) is the most common supraventricular tachyarrhythmia that may be asymptomatic and/or may be associated with rapid haemodynamic deterioration requiring immediate treatment. It is estimated that over 20% AMI patients may have a history of AF, whereas the new-onset arrhythmia may occur in 5% patients with ST elevation myocardial infarction. Importantly, patients who were treated with primary percutaneous coronary intervention for AMI and developed AF have higher rates of adverse events and mortality compared with subjects free of arrhythmia. The scope of this position document is to cover the clinical implications and pharmacological/non-pharmacological management of arrhythmias in emergency presentations and during revascularization. Current evidence for clinical relevance of specific types of VAs complicating AMI in relation to arrhythmia timing has been discussed.

Cardiac intramural electrical mapping reveals focal delays but no conduction velocity slowing in the peri-infarct region

Altered electrical behavior alongside healed myocardial infarcts (MIs) is associated with increased risk of sudden cardiac death. However, the multidimensional mechanisms are poorly understood and described. This study characterizes, for the first time, the intramural spread of electrical activation in the peri-infarct region of chronic reperfusion MIs. Four sheep were studied 13 wk after antero-apical reperfusion infarction. Extracellular potentials (ECPs) were recorded in a ~20 × 20-mm² region adjacent to the infarct boundary (25 plunge needles <0.5-mm diameter with 15 electrodes at 1-mm centers) during multisite stimulation. Infarct geometry and electrode locations were reconstructed from magnetic resonance images. Three-dimensional activation spread was characterized by local activation times and interpolated ECP fields (n = 191 records). Control data were acquired in 4 non-infarcted sheep (n = 96 records). Electrodes were distributed uniformly around 15 ± 5% of the intramural infarct boundary. There were marked changes in pacing success and ECP morphology across a functional border zone (BZ) ±2 mm from the boundary. Stimulation adjacent to the infarct boundary was associated with low-amplitude electrical activity within the BZ and delayed activation of surrounding myocardium. Bulk tissue depolarization occurred 3.5-14.6 mm from the pacing site for 39% of stimuli with delays of 4-37 ms, both significantly greater than control (P < 0.0001). Conduction velocity (CV) adjacent to the infarct was not reduced compared with control, consistent with structure-only computer model results. Insignificant CV slowing, irregular stimulus-site specific activation delays, and obvious indirect activation pathways strongly suggest that the substrate for conduction abnormalities in chronic MI is predominantly structural in nature.NEW & NOTEWORTHY Intramural in vivo measurements of peri-infarct electrical activity were not available before this study. We use pace-mapping in a three-dimensional electrode array to show that a subset of stimuli in the peri-infarct region initiates coordinated myocardial activation some distance from the stimulus site with substantial associated time delays. This is site dependent and heterogeneous and occurs for <50% of ectopic stimuli in the border zone. Furthermore, once coordinated activation is initiated, conduction velocity adjacent to the infarct boundary is not significantly different from control. These results give new insights to peri-infarct electrical activity and do not support the widespread view of uniform electrical remodeling in the border zone of chronic myocardial infarcts, with depressed conduction velocity throughout.

Role of catheter ablation in patients with ischemic ventricular tachycardia: From basic to clinical practice

Catheter ablation provides a therapeutic option for decreasing episodes of ventricular tachycardia in patients with coronary artery disease. Clinical studies show improvement with catheter ablation in reducing arrhythmia recurrence and therapy from implantable defibrillators, but not in decreasing mortality. Ablation can be an important tool for patients with electrical storm. Overall, complication rates of catheter ablation are acceptable, but recurrence rates are still significant. Advances in mapping and ablation technologies could be expected to improve the success rates and reduce the mortality.

Comparison of the Ventricular Tachycardia Circuit Between Patients With Ischemic and Nonischemic Cardiomyopathies

Background:

There has been increasing awareness of the 3-dimensional nature of ventricular tachycardia (VT) circuits. VT circuits in patients with ischemic cardiomyopathies (ICM) and non-ICM (NICM) may differ in this regard.

Methods:

Among patients with structural heart disease and at least 1 hemodynamically tolerated VT undergoing ablation, we retrospectively analyzed responses to all entrainment maneuvers.

Results:

Of 445 patients (ICM 228, NICM 217) undergoing VT ablation, detailed entrainment mapping of at least 1 tolerated VT was performed in 111 patients (ICM 71, NICM 40). Of 89 ICM VTs, the isthmus could be identified by endocardial entrainment in 55 (62%), compared with only 8 of 47 (17%) NICM VTs ( P <0.01). With combined endocardial and epicardial mapping, the isthmus could be identified in 56 (63%) ICM VTs and 12 (26%) NICM VTs ( P <0.01), whereas any critical component (defined as entrance, isthmus or exit) could be identified in 76 (85%) ICM VTs and 37 (79%) NICM VTs ( P =0.3). Complete success (no inducible VT at the end of ablation, 82% versus 65%, P =0.04) and 1-year, single-procedure VT-free survival (82% versus 55%, P <0.01) were both higher among patients with ICM.

Conclusions:

Among mappable ICM VTs, critical circuit components can usually be identified on the endocardium. In contrast, among mappable NICM VTs, although some critical component can typically be identified with the addition of epicardial mapping, the isthmus is less commonly identified, possibly due to midmyocardial location.

2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.

Rationale and design of BERLIN VT study: a multicenter randomised trial comparing preventive versus deferred ablation of ventricular tachycardia

INTRODUCTION

Catheter ablation (CA) has shown to effectively reduce the burden of ventricular tachycardia in patients with implanted cardioverter-defibrillator (ICD). However, in patients with ICD implantation for secondary prevention of ventricular tachycardia (VT), the appropriate time point of CA and its effect on mortality and heart failure progression remains a matter of debate.

METHODS AND ANALYSIS

We present the design of the ongoing preventive aB lation of vE ntriculartachyca R dia in patients with myocardia LIN farction (BERLIN VT) study that aims to prospectively enrol 208 patients with a stable ischaemic cardiomyopathy, a left ventricular ejection fraction of 30% to 50% and documented ventricular tachycardia. Patients will be 1:1 randomised to undergo CA at the time of ICD implantation or CA after the third appropriate ICD shock for ventricular tachycardia. ICD implantation will be performed in all patients. The primary endpoint is defined as the time to first event comprising all-cause mortality and unplanned hospital admission for congestive heart failure or for symptomatic VT/ventricular fibrillation. The patients will be followed until study termination according to the event driven design. Completion of enrolment is expected for mid of 2019.

ETHICS AND DISSEMINATION

The study had been approved by the "Ethik-kommission der Landesärztekammer Hamburg" as well as the local institutional review boards for each of the participation sites. The results of the trial will be published in peer-reviewed journals TRIAL REGISTRATION NUMBER: NCT02501005.

A novel pacing maneuver to verify the postpacing interval minus the tachycardia cycle length while adjusting for decremental conduction: Using "dual-chamber entrainment" for improved supraventricular tachycardia discrimination

BACKGROUND

The postpacing interval (PPI) minus the tachycardia cycle length (TCL) is frequently used to investigate tachycardias. However, a variety of issues (eg, failure to entrain, decremental conduction, and oscillating TCLs) can make interpretation of the PPI-TCL challenging.

OBJECTIVE

The purpose of this study was to investigate a novel maneuver to confirm the PPI-TCL value without using either the ventricular PPI or the TCL interval and to assess the ability of this maneuver to identify decremental conduction and differentiate supraventricular tachycardias.

METHODS

We analyzed 77 intracardiac recordings from patients (age 25 ± 20 years; 40 female) who underwent catheter ablation of atrioventricular nodal reentrant tachycardia (AVNRT) or orthodromic reciprocating tachycardia (ORT) with a concealed pathway. We calculated the PPI-TCL, the AH-corrected PPI-TCL, and estimated the PPI-TCL using "dual-chamber entrainment" calculated as [PPIV - TCL = Stim(A→V) + Stim(V→A) - PPIA].

RESULTS

The PPI-TCL calculated by dual-chamber entrainment highly correlated with the observed and AH-corrected PPI-TCL (R2 = 0.79 and 0.96, respectively; P <.001]. A dual-chamber entrainment PPI-TCL value of 80 ms correctly differentiated all AVNRT from septal ORT cases, whereas the standard PPI-TCL and AH-corrected PPI-TCL methods were incorrect in 14% and 6% of cases, respectively. Dual-chamber entrainment identified 3 ± 10 ms of additional decremental conduction beyond AH prolongation, including 4 pathways with significant (>10 ms) decrement.

CONCLUSION

Dual-chamber entrainment estimates the PPI-TCL value without using either the ventricular PPI or the TCL interval. This maneuver adjusts for all decremental conduction, including within concealed pathways, where a dual-chamber entrainment PPI-TCL value >80 ms favors AVNRT over ORT. This maneuver can be used to verify the observed PPI-TCL value in challenging cases.

Substrate mapping for scar-related ventricular tachycardia in patients with resynchronization therapy-the importance of the pacing mode

PURPOSE

Targets for substrate-based catheter ablation of scar-related ventricular tachycardia (VT) include sites with fractionated and late potentials (LPs). We hypothesized that in patients with cardiac resynchronization therapy (CRT), the pacing mode may influence the timing of abnormal electrograms (EGMs) relative to the surface QRS complex.

METHODS

We assessed bipolar EGM characteristics in left ventricular low bipolar voltage areas (< 1.5 mV) from 10 patients with coronary disease and a CRT device undergoing catheter ablation for VT. EGMs at 81 sites were analyzed during three different pacing modes (biventricular (BiV), right ventricular (RV)-only, and left ventricular (LV)-only) pacing.

RESULTS

Stimulus to end of local electrogram duration (Stim-to-eEGM) depended significantly on the stimulation site (BiV, LV, or RV, p = 0.032). Single-chamber pacing unmasked LPs, not present during BiV pacing, in three patients. In another three patients, a concomitant increase in stimulus to end of surface QRS duration caused by single-site pacing compensated for the increase in Stim-to-eEGM duration, thereby prohibiting LP unmasking.

CONCLUSION

The sequence of ventricular activation, as determined by the pacing site in patients with CRT devices, has a major influence on the detection of late potentials during substrate-guided ablation. Further study is warranted to define the optimal approaches, including the rhythm, for substrate mapping, but our findings suggest that BiV pacing may be most likely to obscure detection of late potentials as compared to single-site pacing.

Substrate Mapping and Ablation for Ventricular Tachycardia in Patients with Structural Heart Disease: How to Identify Ventricular Tachycardia Substrate

Catheter ablation for ventricular tachycardia (VT) has been increasingly used over the past two decades in patients with structural heart disease (SHD). In these individuals, a substrate mapping strategy is being more commonly applied to identify targets for VT ablation, which has been shown to be more effective versus targeting mappable VTs alone. There are a number of substrate mapping methods in existence that aim to explore potential VT isthmuses, although their success rates vary. Most of the reported electrogram-based mapping studies have been performed with ablation catheters; meanwhile, the use of multipolar mapping catheters with smaller electrodes and closer interelectrode spacing has emerged, which allows for an assessment of detailed near-field abnormal electrograms at a higher resolution. Another recent advancement has occurred in the use of imaging techniques in VT ablation, particularly in refining the substrate. The goal of this paper is to review the key developments and limitations of current mapping strategies of substrate-based VT ablation and their outcomes. In addition, we briefly summarize the role of cardiac imaging in delineating VT substrate.

Catheter Treatment of Ventricular Tachycardia: A Reference-Less Pace-Mapping Method to Identify Ablation Targets

OBJECTIVE

A novel method is developed to identify ablation targets for the catheter treatment of ventricular tachycardia (VT).

METHODS

The method is based on pace-mapping, which is a validated technique to determine the catheter ablation targets. Conventionally, it consists of stimulating the heart ventricle from various sites and comparing the resulting activation pathways to that of a clinical VT by the analysis of surface electrocardiograms (ECG). In this paper, a novel pace-mapping method is presented, which does not require a reference ECG recording of the VT. A three-dimensional correlation gradient map is reconstructed by semiautomatic analysis of ECG morphological changes within the network of pace-mapping sites. In these maps, abnormal points are identified by high correlation gradient values (i.e., corresponding to slow propagation of the electric influx, as in the core of the reentrant VT circuit). The relation between the conventional and reference-less method is described theoretically and evaluated in a retrospective study including 24 VT ablation procedures.

RESULTS

The "reference-less" method was able to identify normal points with a high accuracy (negative predictive value: NPV = 97%), and to detect more abnormal points, as predicted by the theory. Correlation gradients computed by the proposed method were significantly higher in ablation zones than in other zones of the ventricle (p < 10^-12), indicating excellent prediction of the ablation targets.

SIGNIFICANCE

The reference-less method might either be used in complement of the conventional method or to treat patients in whom VT cannot be induced during the intervention.

Outcomes of Catheter Ablation of Ventricular Tachycardia Based on Etiology in Nonischemic Heart Disease: An International Ventricular Tachycardia Ablation Center Collaborative Study

OBJECTIVES

This study sought to characterize ventricular tachycardia (VT) ablation outcomes across nonischemic cardiomyopathy (NICM) etiologies and adjust these outcomes by patient-related comorbidities that could explain differences in arrhythmia recurrence rates.

BACKGROUND

Outcomes of catheter ablation of VT in patients with NICM could be related to etiology of NICM.

METHODS

Data from 2,075 patients with structural heart disease referred for catheter ablation of VT from 12 international centers was retrospectively analyzed. Patient characteristics and outcomes were noted for the 6 most common NICM etiologies. Multivariable Cox proportional hazards modeling was used to adjust for potential confounders.

RESULTS

Of 780 NICM patients (57 ± 14 years of age, 18% women, left ventricular ejection fraction 37 ± 13%), underlying prevalence was 66% for dilated idiopathic cardiomyopathy (DICM), 13% for arrhythmogenic right ventricular cardiomyopathy (ARVC), 6% for valvular cardiomyopathy, 6% for myocarditis, 4% for hypertrophic cardiomyopathy, and 3% for sarcoidosis. One-year freedom from VT was 69%, and freedom from VT, heart transplantation, and death was 62%. On unadjusted competing risk analysis, VT ablation in ARVC demonstrated superior VT-free survival (82%) versus DICM (p ≤ 0.01). Valvular cardiomyopathy had the poorest unadjusted VT-free survival, at 47% (p < 0.01). After adjusting for comorbidities, including age, heart failure severity, ejection fraction, prior ablation, and antiarrhythmic medication use, myocarditis, ARVC, and DICM demonstrated similar outcomes, whereas hypertrophic cardiomyopathy, valvular cardiomyopathy, and sarcoidosis had the highest risk of VT recurrence.

CONCLUSIONS

Catheter ablation of VT in NICM is effective. Etiology of NICM is a significant predictor of outcomes, with ARVC, myocarditis, and DICM having similar but superior outcomes to hypertrophic cardiomyopathy, valvular cardiomyopathy, and sarcoidosis, after adjusting for potential covariates.

Electrocardiographic criteria of epicardial ventricular tachycardia with anterior origin

BACKGROUND

ECG criteria for identifying an epicardial origin of ventricular tachycardia (VT) have mainly been described for VTs with basal-superior and lateral origin.

OBJECTIVE

The aim of this study was to determine ECG criteria for epicardial VTs with anterior origin as a guide for trans-pericardial ablation.

RESULTS

Among 22 patients undergoing successful ablation of VTs from the anterior myocardial wall, 14 patients underwent endocardial ablation and 8 patients underwent epicardial ablation. VTs with anterior origin ablated epicardially had widened QS complexes in precordial leads with staircase-shaped notching and slowing of the descent to the nadir of S. In comparison, endocardial VTs with anterior origin usually had narrower QS complexes with a smooth and fast downstroke to the nadir of S. The duration of the negative pseudodelta wave was longer in epicardial VTs (55 ± 12 ms) compared to endocardial VTs (22 ± 12 ms). The interval "time to the nadir of S" in patients with anterior VT origin was longer in epicardial VTs (121 ± 16 ms) than in endocardial VTs (80 ± 22 ms). The QRS duration was also longer in patients with epicardial origin (212 ± 19 ms) than with endocardial VT origin (166 ± 30 ms).

CONCLUSIONS

Epicardial origin of VTs arising from the anterior myocardial wall produces a slowing, widening and staircase-shaped notching in the initial VT-QS complex. Thus, the morphology of the initial part of the QS complex in precordial leads can be used as a guide for trans-pericardial ablation of VTs with anterior origin.

Repeat ablation of refractory ventricular arrhythmias in patients with nonischemic cardiomyopathy: Impact of midmyocardial substrate and role of adjunctive ablation techniques

INTRODUCTION

Multiple ablations are often necessary to manage ventricular arrhythmias (VAs) in nonischemic cardiomyopathy (NICM) patients. We assessed characteristics and outcomes and role of adjunctive, nonstandard ablation in repeat VA ablation (RAbl) in NICM.

METHODS AND RESULTS

Consecutive NICM patients undergoing RAbl were analyzed, with characteristics of the last VA ablations compared between those undergoing 1 versus multiple-repeat ablations (1-RAbl vs. >1RAbl), and between those with or without midmyocardial substrate (MMS). VA-free survival was compared. Eighty-eight patients underwent 124 RAbl, 26 with > 1RAbl, and 26 with MMS. 1-RAbl and > 1-RAbl groups were similar in age (57 ± 16 vs. 57 ± 17 years; P = 0.92), males (76% vs. 69%; P = 0.60), LVEF (40 ± 17% vs. 40 ± 18%; P = 0.96), and amiodarone use (31% vs. 46%, P = 0.22). One-year VA freedom between 1-RAbl vs. > 1RAbl was similar (82% vs. 80%; P = 0.81); adjunctive ablation was utilized more in >1RAbl (31% vs. 11%, P = 0.02), and complication rates were higher (27% vs. 7%, P = 0.01), most due to septal substrate and anticipated heart block. >1-RAbl patients had more MMS (62% vs. 16%, P < 0.01). Although MMS was associated with worse VA-free survival after 1-RAbl (43% vs. 69%, P = 0.01), when >1RAbl was performed, more often with nonstandard ablation, VA-free survival was comparable to non-MMS patients (85% vs. 81%; P = 0.69). More RAbls were required in MMS versus non-MMS patients (2.00 ± 0.98 vs. 1.16 ± 0.37; P < 0.001).

CONCLUSION

For NICM patients with recurrent, refractory VAs despite previous ablation, effective arrhythmia control can safely be achieved with subsequent ablation, although >1 repeat procedure with adjunctive ablation is often required, especially with MMS.

Field of view of mapping catheters quantified by electrogram associations with radius of myocardial attenuation on contrast-enhanced cardiac computed tomography

BACKGROUND

Contrast-enhanced cardiac computed tomography (CE-CT) provides useful substrate characterization in patients with ventricular tachycardia (VT).

OBJECTIVE

The purpose of this study was to describe the association between endocardial electrogram measurements and myocardial characteristics on CE-CT, in particular the field of view of electrogram features.

METHODS

Fifteen patients with postinfarct VT who underwent catheter ablation with preprocedural CE-CT were included. Electroanatomic maps were registered to CE-CT, and myocardial attenuation surrounding each endocardial point was measured at a radius of 5, 10, and 15 mm. The association between endocardial voltage and attenuation was assessed using a multilevel random effects linear regression model, clustered by patient, with best model fit defined by highest log likelihood.

RESULTS

A total of 4698 points were included. There was a significant association of bipolar and unipolar voltage with myocardial attenuation at all radii. For unipolar voltage, the best model fit was at an analysis radius of 15 mm regardless of the mapping catheter used. For bipolar voltage, the best model fit was at an analysis radius of 15 mm for points acquired with a conventional ablation catheter. In contrast, the best model fit for points acquired with a multipolar mapping catheter was at an analysis radius of 5 mm.

CONCLUSION

Myocardial attenuation on CE-CT indicates a smaller myocardial field of view of bipolar electrograms using multipolar catheters with smaller electrodes in comparison to standard ablation catheters despite similar interelectrode spacing. Smaller electrodes may provide improved spatial resolution for the definition of myocardial substrate for VT ablation.

Automatically computed ECG algorithm for the quantification of myocardial scar and the prediction of mortality

BACKGROUND

Myocardial scar is associated with adverse cardiac outcomes. The Selvester QRS-score was developed to estimate myocardial scar from the 12-lead ECG, but its manual calculation is difficult. An automatically computed QRS-score would allow identification of patients with myocardial scar and an increased risk of mortality.

OBJECTIVES

To assess the diagnostic and prognostic value of the automatically computed QRS-score.

METHODS

The diagnostic value of the QRS-score computed automatically from a standard digital 12-lead was prospectively assessed in 2742 patients with suspected myocardial ischemia referred for myocardial perfusion imaging (MPI). The prognostic value of the QRS-score was then prospectively tested in 1151 consecutive patients presenting to the emergency department (ED) with suspected acute heart failure (AHF).

RESULTS

Overall, the QRS-score was significantly higher in patients with more extensive myocardial scar: the median QRS-score was 3 (IQR 2-5), 4 (IQR 2-6), and 7 (IQR 4-10) for patients with 0, 5-20 and > 20% myocardial scar as quantified by MPI (p < 0.001 for all pairwise comparisons). A QRS-score ≥ 9 (n = 284, 10%) predicted a large scar defined as > 20% of the LV with a specificity of 91% (95% CI 90-92%). Regarding clinical outcomes in patients presenting to the ED with symptoms suggestive of AHF, mortality after 1 year was 28% in patients with a QRS-score ≥ 3 as opposed to 20% in patients with a QRS-score < 3 (p = 0.001).

CONCLUSIONS

The QRS-score can be computed automatically from the 12-lead ECG for simple, non-invasive and inexpensive detection and quantification of myocardial scar and for the prediction of mortality. TRIAL-REGISTRATION: http://www.clinicaltrials.gov . Identifier, NCT01838148 and NCT01831115.

Differentiating Ventricular From Supraventricular Arrhythmias Using the Postpacing Interval After Failed Antitachycardia Pacing

BACKGROUND

Implantable cardioverter defibrillator arrhythmia discrimination algorithms often are unable to discriminate ventricular from supraventricular arrhythmias. We sought to evaluate whether the response to antitachycardia pacing (ATP) in patients with an implantable cardioverter defibrillator could further discriminate ventricular from supraventricular arrhythmias in patients receiving ATP.

METHODS AND RESULTS

All episodes of ventricular or supraventricular tachycardia where ATP was delivered in patients enrolled in RAFT (Cardiac-Resynchronization Therapy for Mild-to-Moderate Heart Failure Trial) were included. RAFT randomized 1798 patients with New York Heart Association class II/III heart failure, left ventricular ejection fraction ≤30%, and QRS duration of ≥120 ms to a implantable cardioverter defibrillator±cardiac resynchronization therapy. The tachycardia cycle lengths (TCLs) before and after the delivery of ATP and the postpacing intervals were assessed. Overall, 10 916 ATP attempts were reviewed for 8150 tachycardia episodes in 924 patients. After excluding tachycardias where ATP terminated the episode or where the specific mechanism of the tachycardia was uncertain, we analyzed 3676 ATP attempts delivered for 2046 tachycardia episodes in 541 patients. A shorter difference between postpacing interval and TCL (PPI-TCL) was more likely to be associated with ventricular tachycardia than with supraventricular tachyarrhythmia (138.1±104.2 versus 277.4±126.9 ms; p<0.001). Analysis of the receiver operator curve for the PPI-TCL revealed an area under the curve of 0.803 (p<0.001; 95% confidence interval, 0.784-0.822). The majority of tachycardias with a PPI-TCL >360 ms were supraventricular with a PPI-TCL value of ≤360 ms having a sensitivity of 97.4% and specificity of 28.3% for ventricular tachycardia.

CONCLUSIONS

The ATP response, specifically the PPI-TCL, can further discriminate ventricular from supraventricular arrhythmias in patients with implantable cardioverter defibrillators when the currently available discriminators fail.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique identifier: NCT00251251.

Catheter Ablation of Ventricular Tachycardia in Structural Heart Disease: Indications, Strategies, and Outcomes-Part II

In contrast to ventricular tachycardia (VT) that occurs in the setting of a structurally normal heart, VT that occurs in patients with structural heart disease carries an elevated risk for sudden cardiac death (SCD), and implantable cardioverter-defibrillators (ICDs) are the mainstay of therapy. In these individuals, catheter ablation may be used as adjunctive therapy to treat or prevent repetitive ICD therapies when antiarrhythmic drugs are ineffective or not desired. However, certain patients with frequent premature ventricular contractions (PVCs) or VT and tachycardiomyopathy should be considered for ablation before ICD implantation because left ventricular function may improve, consequently decreasing the risk of SCD and obviating the need for an ICD. The goal of this paper is to review the pathophysiology, mechanism, and management of VT in the setting of structural heart disease and discuss the evolving role of catheter ablation in decreasing ventricular arrhythmia recurrence.

Source-Sink Mismatch Causing Functional Conduction Block in Re-Entrant Ventricular Tachycardia

Ventricular tachycardia (VT) caused by a re-entrant circuit is a life-threatening arrhythmia that at present cannot always be treated adequately. A realistic model of re-entry would be helpful to accurately guide catheter ablation for interruption of the circuit. In this review, models of electrical activation wavefront propagation during onset and maintenance of re-entrant VT are discussed. In particular, the relationship between activation mapping and maps of transition in infarct border zone thickness, which results in source-sink mismatch, is considered in detail and supplemented with additional data. Based on source-sink mismatch, the re-entry isthmus can be modeled from its boundary properties. Isthmus boundary segments with large transitions in infarct border zone thickness have large source-sink mismatch, and functional block forms there during VT. These alternate with segments having lesser thickness change and therefore lesser source-sink mismatch, which act as gaps, or entrance and exit points, to the isthmus during VT. Besides post-infarction substrates, the source-sink model is likely applicable to other types of volumetric changes in the myocardial conducting medium, such as when there is presence of fibrosis or dissociation of muscle fibers.

Suppression of turbulence by heterogeneities in a cardiac model with fiber rotation

Electrical scroll wave turbulence in human ventricles is associated with ventricular fibrillation and sudden cardiac death. We perform three-dimensional simulations on the basis of the anisotropic Fenton-Karma model and show that macroscopic, insulating heterogeneities (e.g., blood vessels) can cause the spontaneous formation of pinned scroll waves. The wave field of these vortices is periodic, and their frequencies are sufficiently high to push the free, turbulent vortices into the system boundaries where they annihilate. Our study considers cylindrical heterogeneities with radii in the range of 0.1 to 2 cm that extend either in the transmural or a perpendicular direction. Thick cylinders cause the spontaneous formation of multi-armed rotors according to a radius-dependence that is explained in terms of two-dimensional dynamics. For long cylinders, local pinning contacts spread along the heterogeneity by fast and complex self-wrapping.

Characterization of Ventricular Tachycardia After Left Ventricular Assist Device Implantation as Destination Therapy: A Single-Center Ablation Experience

OBJECTIVES

This study sought to report mechanisms of ventricular tachycardia (VT) and outcomes of VT ablation in patients with a left ventricular assist device (LVAD) as destination therapy.

BACKGROUND

Continuous flow LVAD implantation plays a growing role in the management of end-stage heart failure, and VT is common. There are limited reports of VT ablation in patients with a destination LVAD.

METHODS

Patients with a continuous-flow LVAD referred for VT ablation from 2010 to 2016 were analyzed retrospectively. Baseline patient characteristics, procedural data, and clinical follow-up were evaluated. Arrhythmia-free survival was assessed.

RESULTS

Twenty-one patients (90% male, 62 ± 10 years) underwent catheter ablation of VT at a median of 191 days (interquartile range: 55 to 403 days) after LVAD implantation (15 HeartMate II, 6 HeartWare HVAD). Five patients (24%) had termination (n = 4) or slowing (n = 1) of VT with ablation near the apical inflow cannula, and 3 (14%) had bundle-branch re-entry. Freedom from recurrent VT among surviving patients was 64% at 1 year, with overall survival 67% at 1 year for patients without arrhythmia recurrence and 29% for patients with recurrence (p = 0.049). One patient had suspected pump thrombosis within 30 days of the ablation procedure, with no other major acute complications.

CONCLUSIONS

In this relatively large, single-center experience of VT ablation in destination LVAD, freedom from recurrent VT and implantable cardioverter-defibrillator shocks was associated with improved 1-year survival. Bundle branch re-entry was more prevalent than anticipated, and cannula-adjacent VT was less common. This challenging population remains at risk for late pump thrombosis and mortality.