Improving Outcomes in Ventricular Tachycardia Ablation Using Imaging to Identify Arrhythmic Substrates

Ventricular Tachycardia Ablation in Patients With Severely Decreased Left Ventricular Ejection Fraction

BACKGROUND

Ablation of ventricular tachycardia (VT) is often performed in patients with structural heart disease. Procedural and delayed enhancement cardiac magnetic resonance imaging (DE-CMR) characteristics among patients with very severe cardiomyopathy (CM) and without left-ventricular assist devices (LVAD) have been incompletely described.

OBJECTIVES

To examine procedural and imaging characteristics of patients with very severely decreased ejection fractions undergoing VT ablation procedures.

METHODS

Consecutive patients with a left ventricular ejection fraction (EF) < 20% and without LVADs who underwent VT ablation were included. A composite outcome of survival free from VT, LVAD, or transplant was examined.

RESULTS

Twenty-seven patients were included (64.1 ± 7.76 years; male n = 23, 88.5%; EF 12.8 ± 3%, LV end diastolic diameter 74 ± 11 mm, ischemic CM (n = 16, 60%), Nonischemic CM (n = 9, 52%), mixed CM (n = 2, 7%)). Twenty-five (93%) patients had failed amiodarone, 9 (33%) had a prior VT ablation, and 13 (48%) underwent ablation for VT storm. Scar was present in 22/23 patients with DE-CMR (intramural [n = 13], endocardial [n = 8], epicardial [n = 2], mixed components [n = 12]). DE-CMR scar corresponded to VT sites of origin in 18/22 patients (82%), excluding one patient with right ventricular VT, two with bundle-branch-reentry VT, and one-non-inducible patient. After 22 ± 19 months, VT occurred in 15/27(56%) patients, death 8/27(30%) and the composite outcome occurred in 22/27(82%) patients.

CONCLUSION

Patients with very severe cardiomyopathy undergoing VT ablation represent a high risk population, experiencing high rates of VT recurrence and death on midterm follow up. Despite severe remodeling, DE-CMR provides localizing information on the arrhythmia site of origin.

Catheter ablation compared to medical therapy for ventricular tachycardia in sarcoidosis: nationwide outcomes and hospital readmissions

Background

Catheter ablation (CA) for ventricular tachycardia (VT) can be a useful treatment strategy, however, few studies have compared CA to medical therapy (MT) in the sarcoidosis population.

Objective

To assess in-hospital outcomes and unplanned readmissions following CA for VT compared to MT in patients with sarcoidosis.

Methods

Data was obtained from the Nationwide Readmissions Database between 2010 and 2019 to identify patients with sarcoidosis admitted for VT either undergoing CA or MT during elective and non-elective admission. Primary endpoints were a composite endpoint of inpatient mortality, cardiogenic shock, cardiac arrest and 30-day hospital readmissions. Procedural complications at index admission and causes of readmission were also identified.

Results

Among 1581 patients, 1217 with sarcoidosis and VT underwent MT compared to 168 with CA during non-elective admission. 63 patients admitted electively underwent CA compared with 129 managed medically. There was no difference in the composite outcome for patients undergoing catheter ablation or medical therapy during both non-elective (9.0 % vs 12.0 %, p = 0.312) and elective admission (3.2 % vs. 7.8 %, p = 0.343). The most common cause of readmission were ventricular arrhythmias (VA) in both groups, however, those undergoing elective CA were less likely to be readmitted for VA compared to non-elective CA. The most common complication in the CA group was cardiac tamponade (4.8 %).

Conclusion

VT ablation is associated with similar rates of 30-day readmission compared to MT and does not confer increased risk of harm with respect to inpatient mortality, cardiogenic shock or cardiac arrest. Further research is warranted to determine if a subgroup of sarcoidosis patients admitted with VT are better served with an initial conservative management strategy followed by VT ablation.

Optimizing ventricular tachycardia ablation through imaging-based assessment of arrhythmic substrate: A comprehensive review and roadmap for the future

Ventricular tachycardia (VT) is a life-threatening heart rhythm and has long posed a complex challenge in the field of cardiology. Recent developments in advanced imaging modalities have aimed to improve comprehension of underlying arrhythmic substrate for VT. To this extent, high-resolution cardiac magnetic resonance (CMR) and cardiac computed tomography (CCT) have emerged as tools for accurately visualizing and characterizing scar tissue, fibrosis, and other critical structural abnormalities within the heart, providing novel insights into VT triggers and substrate. However, clinical implementation of knowledge derived from these advanced imaging techniques in improving VT treatment and guiding invasive therapeutic strategies continues to pose significant challenges. A pivotal concern lies in the absence of standardized imaging protocols and analysis methodologies, resulting in a large variance in data quality and consistency. Furthermore, the clinical significance and outcomes associated with VT substrate characterization through CMR and CCT remain dynamic and subject to ongoing evolution. This highlights the need for refinement of these techniques before their reliable integration into routine patient care can be realized. The primary objectives of this study are twofold: firstly, to provide a comprehensive overview of the studies conducted over the last 15 years, summarizing the current available literature on imaging-based assessment of VT substrate. Secondly, to critically analyze and evaluate the selected studies, with the aim of providing valuable insights that can inform current clinical practice and future research.

Role of Nuclear Imaging in Cardiac Stereotactic Body Radiotherapy for Ablation of Ventricular Tachycardia

Ventricular tachycardia (VT) is a life-threatening arrhythmia common in patients with structural heart disease or nonischemic cardiomyopathy. Many VTs originate from regions of fibrotic scar tissue, where delayed electrical signals exit scar and re-enter viable myocardium. Cardiac stereotactic body radiotherapy (SBRT) has emerged as a completely noninvasive alternative to catheter ablation for the treatment of recurrent or refractory ventricular tachycardia. While there is no common consensus on the ideal imaging workflow, therapy planning for cardiac SBRT often combines information from a plurality of imaging modalities including MRI, CT, electroanatomic mapping and nuclear imaging. MRI and CT provide detailed anatomic information, and late enhancement contrast imaging can indicate regions of fibrosis. Electroanatomic maps indicate regions of heterogenous conduction voltage or early activation which are indicative of arrhythmogenic tissue. Some early clinical adopters performing cardiac SBRT report the use of myocardial perfusion and viability nuclear imaging to identify regions of scar. Nuclear imaging of hibernating myocardium, inflammation and sympathetic innervation have been studied for ventricular arrhythmia prognosis and in research relating to catheter ablation of VT but have yet to be studied in their potential applications for cardiac SBRT. The integration of information from these many imaging modalities to identify a target for ablation can be challenging. Multimodality image registration and dedicated therapy planning tools may enable higher target accuracy, accelerate therapy planning workflows and improve patient outcomes. Understanding the pathophysiology of ventricular arrhythmias, and localizing the arrhythmogenic tissues, is vital for successful ablation with cardiac SBRT. Nuclear imaging provides an arsenal of imaging strategies to identify regional scar, hibernation, inflammation, and sympathetic denervation with some advantages over alternative imaging strategies.