Ventricular Tachycardia Ablation in Nonischemic Cardiomyopathy

Approaching Ventricular Tachycardia Ablation in 2024: An Update on Mapping and Ablation Strategies, Timing, and Future Directions

This review provides insights into mapping and ablation strategies for VT, offering a comprehensive overview of contemporary approaches and future perspectives in the field. The strengths and limitations of classical mapping strategies, namely activation mapping, pace mapping, entrainment mapping, and substrate mapping, are deeply discussed. The increasing pivotal relevance of CMR and MDCT in substrate definition is highlighted, particularly in defining the border zone, tissue channels, and fat. The integration of CMR and MDCT images with EAM is explored, with a special focus on their role in enhancing effectiveness and procedure safety. The abstract concludes by illustrating the Pisa workflow for the VT ablation procedure.

Outcomes of ventricular tachycardia ablation in patients with ischemic and non-ischemic cardiomyopathy: A propensity-score matched analysis

INTRODUCTION AND OBJECTIVES

Catheter ablation (CA) is effective in the treatment of ventricular tachycardia (VT). Although some observational data suggest patients with non-ischemic cardiomyopathy (NICM) have less favorable outcomes when compared to those with an ischemic etiology (ICM), direct comparisons are rarely reported. We aimed to compare the outcomes of VT ablation in a propensity-score matched population of ICM or NICM patients.

METHODS

Single-center retrospective study of consecutive patients undergoing VT ablation from 2012 to 2023. A propensity score (PS) was used to match ICM and NICM patients in a 1:1 fashion according to age, sex, left ventricular ejection fraction (LVEF), NYHA class, electrical storm (ES) at presentation, and previous endocardial ablation. The outcomes of interest were VT-free survival and all-cause mortality.

RESULTS

The PS yielded two groups of 71 patients each (mean age 63±10 years, 92% male, mean LVEF 35±10%, 36% with ES at presentation, and 23% with previous ablation), well matched for baseline characteristics. During a median follow-up of 2.3 (interquartile range IQR 1.3-3.8) years, patients with NICM had a significantly lower VT-free survival (53.5% vs. 69.0%, log-rank p=0.037), although there were no differences regarding all-cause mortality (22.5% vs. 16.9%, log-rank p=0.245). Multivariate analysis identified NICM (HR 2.34 [95% CI 1.32-4.14], p=0.004), NYHA class III/IV (HR 2.11 [95% CI 1.11-4.04], p=0.024), and chronic kidney disease (HR 2.23 [95% CI 1.25-3.96], p=0.006), as independent predictors of VT recurrence.

CONCLUSION

Non-ischemic cardiomyopathy patients were at increased risk of VT recurrence after ablation, although long-term mortality did not differ.

Signal-averaged electrocardiography as a noninvasive tool for evaluating the ventricular substrate in patients with nonischemic cardiomyopathy: reassessment of an old tool

Introduction

Signal-averaged electrocardiography (SAECG) provides diagnostic and prognostic information regarding cardiac diseases. However, its value in other nonischemic cardiomyopathies (NICMs) remains unclear. This study aimed to investigate the role of SAECG in patients with NICM.

Methods and results

This retrospective study included consecutive patients with NICM who underwent SAECG, biventricular substrate mapping, and ablation for ventricular arrhythmia (VA). Patients with baseline ventricular conduction disturbances were excluded. Patients who fulfilled at least one SAECG criterion were categorized into Group 1, and the other patients were categorized into Group 2. Baseline and ventricular substrate characteristics were compared between the two groups. The study included 58 patients (39 men, mean age 50.4 ± 15.5 years), with 34 and 24 patients in Groups 1 and 2, respectively. Epicardial mapping was performed in eight (23.5%) and six patients (25.0%) in Groups 1 and 2 (p = 0.897), respectively. Patients in Group 1 had a more extensive right ventricular (RV) low-voltage zone (LVZ) and scar area than those in Group 2. Group 1 had a larger epicardial LVZ than Group 2. Epicardial late potentials were more frequent in Group 1 than in Group 2. There were more arrhythmogenic foci within the RV outflow tract in Group 1 than in Group 2. There was no significant difference in long-term VA recurrence.

Conclusion

In our NICM population, a positive SAECG was associated with a larger RV endocardial scar, epicardial scar/late potentials, and a higher incidence of arrhythmogenic foci in the RV outflow tract.

Impact of repeat ablation of ventricular tachycardia in patients with structural heart disease

AIMS

Recurrences of ventricular tachycardia (VT) after initial catheter ablation is a significant clinical problem. In this study, we report the efficacy and risks of repeat VT ablation in patients with structural heart disease (SHD) in a tertiary single centre over a 7-year period.

METHODS AND RESULTS

Two hundred ten consecutive patients referred for repeat VT ablation after previous ablation in our institution were included in the analysis (53% ischaemic cardiomyopathy, 91% males, median age 65 years, mean left ventricular ejection fraction 35%). After performing repeat ablation, the clinical VTs were acutely eliminated in 82% of the patients, but 46% of the cohort presented with VT recurrence during the 25-month follow-up. Repeat ablation led to a 73% reduction of shock burden in the first year and 61% reduction until the end of follow-up. Similarly, VT burden was reduced 55% in the first year and 36% until the end of the study. Fifty-two patients (25%) reached the combined endpoint of ventricular assist device implantation, heart transplantation, or death. Advanced New York Heart Association functional class, anteroseptal substrate, and periprocedural complication after repeat ablation were associated with worse prognosis independently of the type of cardiomyopathy.

CONCLUSION

While complete freedom from VT after repeat ablation in SHD was difficult to achieve, ablation led to a significant reduction in VT and shock burden. Besides advanced heart failure characteristics, anteroseptal substrate and periprocedural complications predicted a worse outcome.

Mapping and Ablation of Ventricular Tachycardia in Inherited Left Ventricular Cardiomyopathies

Advances in the field of human genetics have led to an accumulating understanding of the genetic basis of distinct nonischemic cardiomyopathies associated with ventricular tachycardias (VTs) and sudden cardiac death. To date, there is an increasing proportion of patients with inherited cardiomyopathies requiring catheter ablation for VTs. This review provides an overview of disease-causing gene mutations frequently encountered and relevant for clinical electrophysiologists. Available data on VT ablation in patients with an inherited etiology and a phenotype of a nondilated left ventricular cardiomyopathy, dilated cardiomyopathy, or hypertrophic cardiomyopathy are summarized. VTs amenable to catheter ablation are related to nonischemic fibrosis. Recent insights into genotype-phenotype relations of subtype and location of fibrosis have important implications for treatment planning. Current strategies to delineate nonischemic fibrosis and related arrhythmogenic substrates using multimodal imaging, image integration, and electroanatomical mapping are provided. The ablation approach depends on substrate location and extension. Related procedural aspects including patient-tailored (enhanced) ablation strategies and outcomes are outlined. Challenging substrates for VT and the underlying inherited etiologies with a high risk for rapid progressive heart failure contribute to poor outcomes after catheter ablation. Electroanatomical data obtained during ablation may allow the identification of patients at particular risk who need to be considered for early work-up for left ventricular assist device implantation or heart transplantation.

Personalized Management of Sudden Death Risk in Primary Cardiomyopathies: From Clinical Evaluation and Multimodality Imaging to Ablation and Cardioverter-Defibrillator Implant

Sudden cardiac death represents the leading cause of death worldwide; although the majority of sudden deaths occur in an elderly population with coronary artery disease, some occur in young and otherwise healthy individuals, as is the case of cardiomyopathies. The aim of the present review is to provide a stepwise hierarchical approach for the global sudden death risk estimation in primary cardiomyopathies. Each individual risk factor is analyzed for its contribution to the overall risk of sudden death for each specific cardiomyopathy as well as across all primary myocardial diseases. This stepwise hierarchical and personalized approach starts from the clinical evaluation, subsequently passes through the role of electrocardiographic monitoring and multimodality imaging, and finally concludes with genetic evaluation and electro-anatomical mapping. In fact, the sudden cardiac death risk assessment in cardiomyopathies depends on a multiparametric approach. Moreover, current indications for ventricular arrhythmia ablation and defibrillator implantation are discussed.

Pleomorphic Ventricular Tachycardia in Dilated Cardiomyopathy Predicts Ventricular Tachycardia Recurrence After Ablation Independent From Cardiac Function: Comparison With Patients With Ischemic Heart Disease

BACKGROUND

In dilated cardiomyopathy (DCM), outcome after catheter ablation of ventricular tachycardia (VT) is modest, compared with ischemic heart disease (IHD). Pleomorphic VT (PL-VT) has been associated with fibrotic remodeling and end-stage heart failure in IHD. The prognostic role of PL-VT in DCM is unknown.

METHODS

Consecutive IHD (2009-2016) or DCM (2008-2018) patients undergoing ablation for monomorphic VT were included. PL-VT was defined as ≥1 spontaneous change of the 12-lead VT-morphology during the same induced VT episode. Patients were followed for VT recurrence and mortality.

RESULTS

A total of 247 patients (86% men; 63±13 years; IHD n=152; DCM n=95) underwent ablation for monomorphic VT. PL-VT was observed in 22 and 29 patients with IHD and DCM, respectively (14% versus 31%, P=0.003). In IHD, PL-VT was associated with lower LVEF (28±9% versus 34±12%, P=0.02) and only observed in those with LVEF<40%. In contrast, in DCM, PL-VT was not related to LVEF and induced in 27% of patients with LVEF>40%. During a median follow-up of 30 months, 79 (32%) patients died (IHD 48; DCM 31; P=0.88) and 120 (49%) had VT recurrence (IHD 59; DCM 61; P<0.001). PL-VT was associated with mortality in IHD but not in DCM. In IHD, VT recurrence was independently associated with LVEF, number of induced VTs, and procedural noncomplete success. Of note, in DCM, PL-VT (HR, 2.62 [95% CI, 1.47-4.69]), pathogenic mutation (HR, 2.13 [95% CI, 1.16-3.91]), and anteroseptal VT substrate (HR, 1.75 [95% CI, 1.00-3.07]) independently predicted VT recurrence.

CONCLUSIONS

In IHD, PL-VT was associated with low LVEF and mortality. In DCM, PL-VT was not associated with mortality but a predictor of VT recurrence independent from LVEF. PL-VT in DCM may indicate a specific arrhythmic substrate difficult to control by current ablation techniques.

Association of Late-Gadolinium Enhancement in Cardiac Magnetic Resonance with Mortality, Ventricular Arrhythmias, and Heart Failure in Patients with Non-Ischemic Cardiomyopathy: A Systematic Review and Meta-Analysis

Background

Late gadolinium enhancement (LGE) on cardiac magnetic resonance is a predictor of adverse events in patients with nonischemic cardiomyopathy (NICM).

Objective

This meta-analysis evaluated the correlation between LGE and mortality, ventricular arrhythmias (VAs) and sudden cardiac death (SCD), and heart failure (HF) outcomes.

Methods

A literature search was conducted for studies reporting the association between LGE in NICM and the study endpoints. The primary endpoint was mortality. Secondary endpoints included VA and SCD, HF hospitalization, improvement in left ventricular ejection fraction (LVEF) to >35%, and heart transplantation referral. The search was not restricted to time or publication status. The minimum follow-up duration was 1 year.

Results

A total of 46 studies and 10,548 NICM patients (4610 with LGE, 5938 without LGE) were included; mean follow-up was 3 years (range 13-71 months). LGE was associated with increased mortality (odds ratio [OR] 2.9; 95% confidence interval [CI] 2.3-3.8; P < .01) and VA and SCD (OR 4.6; 95% CI 3.5-6.0; P < .01). LGE was associated with an increased risk of HF hospitalization (OR 3.4; 95% CI 2.3-5.0; P < .01), referral for transplantation (OR 5.1; 95% CI 2.5-10.4; P < .01), and decreased incidence of LVEF improvement to >35% (OR 0.2; 95% CI 0.03-0.85; P = .03).

Conclusion

LGE in NICM patients is associated with increased mortality, VA and SCD, and HF hospitalization and heart transplantation referral during long-term follow up. Given these competing risks of mortality and HF progression, prospective randomized controlled trials are required to determine if LGE is useful for guiding prophylactic implantable cardioverter-defibrillator placement in NICM patients.

Outcomes of catheter ablation of ventricular tachycardia in non-ischemic idiopathic dilated cardiomyopathy: A systematic review and meta-analysis

Objective

To perform a systematic review and meta-analysis of available trials regarding the outcomes of ventricular tachycardia (VT) ablation in patients with non-ischemic dilated cardiomyopathy (NIDCM).

Methods

A comprehensive database search of large four electronic databases, including PubMed, Cochrane, Scopus, and Institute for Scientific Information network meta-analysis, identified five studies enrolling 666 patients for patients with idiopathic dilated cardiomyopathy (IDCM) underwent catheter ablation (CA) for VT. The short-term outcomes assessed included procedural success, VT non-inducibility and procedural complications, whereas the long-term outcomes assessed included VT recurrence, heart transplantation, antiarrhythmic drugs (AAD) use after ablation and death.

Results

A total of 5 observational studies reported outcomes in 666 patients with NIDCM undergoing VT CA. The complete procedural success was moderately high; 65.5% of the patients (95% CI 0.402- 0.857, p &lt; 0.001) and the procedural complications occurred in 5.8% of the patients (95% CI 0.040–0.076, P = 0.685). Epicardial mapping and ablation were performed among 61.5% and 37% of patients with NIDCM respectively. During a follow up period of 12 to 45 months, there were VT recurrence in 34.2% of the patients (95% CI 0.301–0.465, p &lt; 0.080), death in 20.2% of the patients (95% CI 0.059–0.283, p &lt; 0.017) and heart transplantation in 12.9% of the patients (95% CI −0.026–0.245, P &lt; 0.012).

Conclusion

Ventricular tachycardia CA is effective and safe approach for management of patients with NIDCM with the epicardial approach to be considered as initial strategy especially in presence of ECG and CMR findings suggestive of epicardial substrate. A multicenter randomized trial is crucial to look at the short- and long-term outcomes of VT ablation in NIDCM especially with the advances in mapping and ablation techniques and predictors of success.

Contemporary approach to catheter ablation of ventricular tachycardia in nonischemic cardiomyopathy

Nonischemic cardiomyopathy (NICM) comprises a heterogenous group of disorders with myocardial dysfunction unrelated to significant coronary disease. As the use of implantable defibrillators has increased in this patient population, catheter ablation is being utilized more frequently to treat NICM patients with ventricular tachycardia (VT). Progress has been made in identifying multiple subtypes of NICM with variable scar patterns. The distribution of scar is often mid-myocardial and subepicardial, and identifying and ablating this substrate can be challenging. Here, we will review the current understanding of NICM subtypes and the outcomes of VT ablation in this population. We will discuss the use of cardiac imaging, electrocardiography, and electroanatomic mapping to define the VT substrate and the ablation techniques required to successfully prevent VT recurrence.

Purkinje network and myocardial substrate at the onset of human ventricular fibrillation: implications for catheter ablation

AIMS

Mapping data of human ventricular fibrillation (VF) are limited. We performed detailed mapping of the activities underlying the onset of VF and targeted ablation in patients with structural cardiac abnormalities.

METHODS AND RESULTS

We evaluated 54 patients (50 ± 16 years) with VF in the setting of ischaemic (n = 15), hypertrophic (n = 8) or dilated cardiomyopathy (n = 12), or Brugada syndrome (n = 19). Ventricular fibrillation was mapped using body-surface mapping to identify driver (reentrant and focal) areas and invasive Purkinje mapping. Purkinje drivers were defined as Purkinje activities faster than the local ventricular rate. Structural substrate was delineated by electrogram criteria and by imaging. Catheter ablation was performed in 41 patients with recurrent VF. Sixty-one episodes of spontaneous (n = 10) or induced (n = 51) VF were mapped. Ventricular fibrillation was organized for the initial 5.0 ± 3.4 s, exhibiting large wavefronts with similar cycle lengths (CLs) across both ventricles (197 ± 23 vs. 196 ± 22 ms, P = 0.9). Most drivers (81%) originated from areas associated with the structural substrate. The Purkinje system was implicated as a trigger or driver in 43% of patients with cardiomyopathy. The transition to disorganized VF was associated with the acceleration of initial reentrant activities (CL shortening from 187 ± 17 to 175 ± 20 ms, P < 0.001), then spatial dissemination of drivers. Purkinje and substrate ablation resulted in the reduction of VF recurrences from a pre-procedural median of seven episodes [interquartile range (IQR) 4-16] to 0 episode (IQR 0-2) (P < 0.001) at 56 ± 30 months.

CONCLUSIONS

The onset of human VF is sustained by activities originating from Purkinje and structural substrate, before spreading throughout the ventricles to establish disorganized VF. Targeted ablation results in effective reduction of VF burden.

KEY QUESTION

The initial phase of human ventricular fibrillation (VF) is critical as it involves the primary activities leading to sustained VF and arrhythmic sudden death. The origin of such activities is unknown.

KEY FINDING

Body-surface mapping shows that most drivers (≈80%) during the initial VF phase originate from electrophysiologically defined structural substrates. Repetitive Purkinje activities can be elicited by programmed stimulation and are implicated as drivers in 37% of cardiomyopathy patients.

TAKE-HOME MESSAGE

The onset of human VF is mostly associated with activities from the Purkinje network and structural substrate, before spreading throughout the ventricles to establish sustained VF. Targeted ablation reduces or eliminates VF recurrence.

Management of ventricular arrhythmias in heart failure: Current perspectives

Congestive heart failure (HF) is a progressive affliction defined as the inability of the heart to sufficiently maintain blood flow. Ventricular arrhythmias (VAs) are common in patients with HF, and conversely, advanced HF promotes the risk of VAs. Management of VA in HF requires a systematic, multimodality approach that comprises optimization of medical therapy and use of implantable cardioverter-defibrillator and/or device combined with cardiac resynchronization therapy. Catheter ablation is one of the most important strategies with the potential to abolish or decrease the number of recurrences of VA in this population. It can be a curative strategy in arrhythmia-induced cardiomyopathy and may even save lives in cases of an electrical storm. Additionally, modulation of the autonomic nervous system and stereotactic radiotherapy have been introduced as novel methods to control refractory VAs. In patients with end-stage HF and refractory VAs, an institution of the mechanical circulatory support device and cardiac transplant may be considered. This review aims to provide an overview of current evidence regarding management strategies of VAs in HF with an emphasis on interventional treatment.

Substrate Characterization and Outcome of Catheter Ablation of Ventricular Tachycardia in Patients With Nonischemic Cardiomyopathy and Isolated Epicardial Scar

BACKGROUND

The substrate for ventricular tachycardia (VT) in left ventricular (LV) nonischemic cardiomyopathy may be epicardial. We assessed the prevalence, location, endocardial electrograms, and VT ablation outcomes in LV nonischemic cardiomyopathy with isolated epicardial substrate.

METHODS

Forty-seven of 531 (9%) patients with LV nonischemic cardiomyopathy and VT demonstrated normal endocardial (>1.5 mV)/abnormal epicardial bipolar low-voltage area (LVA, <1.0 mV and signal abnormality). Abnormal endocardial unipolar LVA (≤8.3 mV) and endocardial bipolar split electrograms and predictors of ablation success were assessed.

RESULTS

Epicardial bipolar LVA (27.3 cm² [interquartile range, 15.8-50.0]) localized to basal (40), mid (8), and apical (3) LV with basal inferolateral LV most common (28/47, 60%). Of 44 endocardial maps available, 40 (91%) had endocardial unipolar LVA (24.5 cm² [interquartile range, 9.4-68.5]) and 29 (67%) had characteristic normal amplitude endocardial split electrograms opposite the epicardial LVA. At mean of 34 months, the VT-free survival was 55% after one and 72% after multiple procedures. Greater endocardial unipolar LVA than epicardial bipolar LVA (hazard ratio, 10.66 [CI, 2.63-43.12], P=0.001) and number of inducible VTs (hazard ratio, 1.96 [CI, 1.27-3.00], P=0.002) were associated with VT recurrence.

CONCLUSIONS

In patients with LV nonischemic cardiomyopathy and VT, the substrate may be confined to epicardial and commonly basal inferolateral. LV endocardial unipolar LVA and normal amplitude bipolar split electrograms identify epicardial LVA. Ablation targeting epicardial VT and substrate achieves good long-term VT-free survival. Greater endocardial unipolar than epicardial bipolar LVA and more inducible VTs predict VT recurrence.

Long-Term Efficacy and Impact on Mortality of Remote Magnetic Navigation Guided Catheter Ablation of Ventricular Arrhythmias

Remote magnetic navigation (RMN) facilitates ventricular arrhythmia (VA) ablation. This study aimed to evaluate the long-term efficacy of RMN-guided ablation for ventricular tachycardia (VT) and premature ventricular contractions (PVC). A total of 176 consecutive patients (mean age 53.23 ± 17.55 years, 37% female) underwent VA ablation for PVC (132 patients, 75%) or VT (44 patients, 25%). The cohort consisted of 119 patients (68%) with idiopathic VA, 31 (18%) with ischemic (ICM), and 26 (15%) with dilated cardiomyopathy (DCM). VA recurrence was observed in 69 patients (39%, mean age 51.71 ± 19.91 years, 23% female) during a follow-up period of 5.48 years (first quartile 770.50 days, second quartile 1101.50 days, third quartile 1615.50 days). Left ventricular ejection fraction <40% lead to a significantly increased risk for VA (p = 0.031*). Multivariate analyses found DCM to be an independent predictor (IP) for VA recurrence (p < 0.001*, hazard ratio (HR) 3.74, confidence interval (CI) 1.58-8.88). ICM resulted in a lower increase in VA recurrence (p = 0.221, HR 1.49, CI 0.79-2.81). Class I/III/IV antiarrhythmic drug therapy (AADs) was also identified as IP for recurrence (p = 0.030*, HR 2.48, CI 1.11-5.68). A total of 16 patients (9%) died within the observational period. RMN-guided ablation of VA lead to acceptable long-term results. An impaired LV function, DCM, and AADs were associated with a significant risk for VA recurrence. Personalized paths are needed to improve efficacy and outcome.

[Ablation of cardiac arrhythmias using a three-dimensional electro-anatomical mapping system in the Instituto Nacional Cardiovascular - INCOR]

Objective

To describe the initial experience in ablation of cardiac arrhythmias using 3D mapping at the Instituto Nacional Cardiovascular INCOR (Lima, Peru).

Methods

A retrospective descriptive study was carried out. During February 2020, data was collected from the medical records of all patients in whom ablation was performed using 3D mapping from July 2017 to December 2019. This procedure was performed in patients with symptomatic arrhythmia refractory to antiarrhythmic therapy.

Results

Data were collected from 123 patients (median age: 46 years, 64.2% male), who had a median time of illness of 6 years. Among the arrhythmias treated, 19% had atrial fibrillation, 17.5% atrial tachycardia, 17.5% idiopathic ventricular arrhythmias, 16.6% Wolf Parkinson White syndrome / Atrioventricular reentrant tachycardia, 11.1% ventricular arrhythmias of the His-Purkinje conduction system, 9.5% scar related ventricular tachycardia associated, 6.4% atrial flutter and 2.4% intranodal tachycardia. The median fluoroscopy time was 26 minutes. Ablation was acutely successful in 95.9% of cases, acute complications were observed in 4.8%, and recurrence-free survival during the first year of follow-up was 74%.

Conclusions

Our experience in ablation of cardiac arrhythmias using 3D mapping had a high acute success rate, low frequency of complications, and one-year recurrence-free survival of 74 %.

CMR-Based Risk Stratification of Sudden Cardiac Death and Use of Implantable Cardioverter-Defibrillator in Non-Ischemic Cardiomyopathy

Non-ischemic cardiomyopathy (NICM) is one of the most important entities for arrhythmias and sudden cardiac death (SCD). Previous studies suggest a lower benefit of implantable cardioverter–defibrillator (ICD) therapy in patients with NICM as compared to ischemic cardiomyopathy (ICM). Nevertheless, current guidelines do not differentiate between the two subgroups in recommending ICD implantation. Hence, risk stratification is required to determine the subgroup of patients with NICM who will likely benefit from ICD therapy. Various predictors have been proposed, among others genetic mutations, left-ventricular ejection fraction (LVEF), left-ventricular end-diastolic volume (LVEDD), and T-wave alternans (TWA). In addition to these parameters, cardiovascular magnetic resonance imaging (CMR) has the potential to further improve risk stratification. CMR allows the comprehensive analysis of cardiac function and myocardial tissue composition. A range of CMR parameters have been associated with SCD. Applicable examples include late gadolinium enhancement (LGE), T1 relaxation times, and myocardial strain. This review evaluates the epidemiological aspects of SCD in NICM, the role of CMR for risk stratification, and resulting indications for ICD implantation.

Prior myocarditis and ventricular arrhythmias: The importance of scar pattern

BACKGROUND

Multiple studies have addressed the importance of anteroseptal scar in patients with nonischemic cardiomyopathy. However, this pattern has never been fully evaluated in patients with prior myocarditis.

OBJECTIVE

The purpose of this study was to evaluate whether anteroseptal scar is associated with worse outcome in patients with prior myocarditis and how it affects the efficacy of catheter ablation (CA).

METHODS

This was a retrospective study of consecutive patients with prior myocarditis and arrhythmic presentation. Cardiac magnetic resonance and electroanatomic voltage mapping were used to identify the scar pattern. Patients were referred for either CA or escalated antiarrhythmic drug (AAD) therapy. The main outcome was ventricular arrhythmia (VA)-free survival according to the presence of anteroseptal scar.

RESULTS

A total of 144 consecutive patients with prior myocarditis were included. Mean age was 42.1 ± 14.9 years, and 58% were men. Ejection fraction was normal in 73% of patients. Anteroseptal scar was present in 44% of cases. Sixty-one patients (42%) underwent CA. Overall, at 2-year follow-up, VA-free survival was 77% in the CA group. After CA, the mean number of AADs taken by each patient decreased from 1.8 to 0.9 per day (p<0.001). The presence of anteroseptal scar was found to be an independent predictor of VA relapse both in patients treated with CA (hazard ratio [HR] 3.6; 95% confidence interval [CI] 1.1-11.4; P = .03) and in the overall population (HR 2.0; 95% CI 1.2-3.5; P = .02) .

CONCLUSION

In patients with prior myocarditis and VA, the presence of anteroseptal scar negatively predicts outcomes irrespective of treatment strategy.

Real-world characteristics and readmissions among patients undergoing ablation for ventricular tachycardia: a retrospective database analysis of commercially insured patients in the USA

BACKGROUND

Radiofrequency catheter ablation is an effective treatment to alleviate symptoms and reduce recurrent implantable cardioverter-defibrillator (ICD/CRT-D) shocks in patients with ventricular tachycardia (VT).

OBJECTIVE

To assess the characteristics and outcomes (complications, inpatient readmissions) of commercially insured patients in the USA undergoing ablation for ischaemic or non-ischaemic VT.

METHODS

Patients aged 18-64 years with a primary diagnosis of VT who underwent ablation between 2006 and 2015 were identified using the IBM MarketScan Commercial Database. The rate of complications including vascular complications, pericarditis, pulmonary embolism and pericardial tamponade over a 30-day post-ablation period (including index admission) was examined. Inpatient readmissions (VT-related, heart failure (HF)-related and non-VT arrhythmia-related) over the 12-month post-ablation period were examined. A Cox regression model was used to determine factors associated with inpatient readmissions.

RESULTS

5242 patients (488 with ischaemic and 4754 with non-ischaemic VT) met the study criteria. The majority of VT ablations occurred in an outpatient setting (57% for ischaemic and 66% for non-ischaemic VT). Among complications, vascular complications were most frequent (2.05% among ischaemic and 1.6% among non-ischaemic VT patients) over the 30-day post-ablation period. Among ischaemic VT patients, 17%, 7.6% and 4.7% had VT-related, HF-related and non-VT arrhythmia-related inpatient readmissions, respectively in the 12-month post-ablation period. For non-ischaemic VT patients, these numbers were 7.5%, 1.7% and 3.1%, respectively. Inpatient setting (vs outpatient), baseline ICD/CRT-D implantation, HF comorbidity and ≥2 prior hospitalisations were associated with a higher risk of post-ablation VT-related inpatient readmissions among ischaemic VT patients. Similar factors also were associated with a higher risk of post-ablation VT-related inpatient readmission among non-ischaemic VT patients.

CONCLUSION

Setting of ablation and comorbidity status were found to influence readmission rates. Complication and readmission rates following VT ablation were low indicating towards the favourable safety profile of VT ablation.

Utility of Computed Tomography to Predict Ventricular Arrhythmias in Patients With Nonischemic Cardiomyopathy Receiving Cardiac Resynchronization Therapy

The residual risk of ventricular arrhythmia (VA) after cardiac resynchronization therapy (CRT) implantation in patients with nonischemic cardiomyopathy (NICM) remains difficult to evaluate. The impact of left ventricular (LV) wall thickness (WT) measured using computed tomography (CT) on the occurrence of VA after CRT implantation has never been investigated. In this pilot study, we examined the association of LV WT and the occurrence of VA in NICM patients receiving CRT. Thirty three patients with NICM scheduled for CRT underwent preprocedural CT. Reduced LV WT was defined as WT <6 mm and quantified as a percentage of total LV area. The end point was the occurrence of VA episode during 2-years follow-up after CRT implantation. During the 2-years follow-up, a total of 37 VA episodes occurred in 6 (18.2%) patients. Patients with VA exhibited significantly higher NT-pro BNP level before CRT implantation. Additionally, CT analysis showed that patients with VA had a higher percentage of total LV with reduced WT compared with those free from VA (49.5% vs 25.8%, respectively; p = 0.005). In multivariable analysis, the total percentage of LV area with WT <6 mm was the only predictor of VA (odds ratio 1.07 [1.00 to 1.14]; p = 0.047). Receiver-operator curves analysis for total percentage of LVWT <6 mm demonstrated that an optimal cut-off value of 40% differentiated patients at risk of VA. In conclusion, LVWT evaluated using cardiac CT is an independent predictor of VA in NICM patients implanted with CRT. Patients with a total percentage of LVWT <6 mm ≥40% are especially at high risk of VA after CRT implantation.

Sustained Monomorphic Ventricular Tachycardia in Nonischemic Heart Disease

As the population of patients with implanted defibrillators has grown, an increasing number of patients nonischemic cardiomyopathies are requiring therapy to reduce ventricular arrhythmias. Most of these arrhythmias are related to areas of ventricular scar. Although the pathophysiology of scar development is not well understood in these diseases, advances in cardiac imaging and mapping are better characterizing the scar locations that give rise to the arrhythmias. Here, we review the pathophysiologic and electrocardiographic correlations that inform ablation strategies for ventricular tachycardia in these diseases.

Role of Imaging in the Management of Ventricular Arrhythmias

The management of ventricular arrhythmias (VA) has evolved over time to an advanced discipline, incorporating many technologies in the diagnosis and treatment of the myriad types of VA. The first application of imaging is in the assessment for structural heart disease, as this has the greatest impact on prognosis. Advanced imaging has its greatest utility in the planning and execution of ablation for VA. The following review outlines the application of different imaging modalities, such as ultrasonography, magnetic resonance imaging, computed tomography, and positron emission tomography, for the treatment of VA.