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

Zero fluoroscopy catheter ablation of premature ventricular contractions: a multicenter experience

BACKGROUND

Catheter ablation has become an established treatment option for premature ventricular complexes (PVCs). The use of fluoroscopy exposes patients and medical staff to potentially harmful stochastic and deterministic effects of ionizing radiations. We sought to analyze procedural outcomes in terms of safety and efficacy using a "zero fluoroscopy" approach for catheter ablation of PVCs.

METHODS

The present retrospective, multicenter, observational study included 131 patients having undergone catheter ablation of PVCs using "zero fluoroscopy" between 2019 and 2020 in four centers compared with another group who underwent the procedure with fluoroscopy.

RESULTS

Median age was 51.0 ± 15.9 years old; males were 77 (58.8%). Among the study population, 26 (19.8%) had a cardiomyopathy. The most frequent PVC origin was right ventricular outflow tract (55%) followed by the left ventricle (16%), LVOT and cusps (13.7%), and aortomitral continuity (5.3%). Acute suppression of PVC was achieved in 127 patients (96.9%). At 12 months, a complete success was documented in 109 patients (83.2%), a reduction in PVC burden in 18 patients (13.7%), and a failure was recorded in four patients (3.1%). Only two minor complications occurred (femoral hematoma and arteriovenous fistula conservatively treated).

CONCLUSIONS

The PVC ablation with a "zero" fluoroscopy approach appears to be a safe procedure with no major complications and good rates of success and recurrence in our multicenter experience.

A comprehensive protocol combining in vivo and ex vivo electrophysiological experiments in an arrhythmogenic animal model

Ventricular arrhythmias contribute significantly to cardiovascular mortality, with coronary artery disease as the predominant underlying cause. Understanding the mechanisms of arrhythmogenesis is essential to identify proarrhythmic factors and develop novel approaches for antiarrhythmic prophylaxis and treatment. Animal models are vital in basic research on cardiac arrhythmias, encompassing molecular, cellular, ex vivo whole heart, and in vivo models. Most studies use either in vivo protocols lacking important information on clinical relevance or exclusively ex vivo protocols, thereby missing the opportunity to explore underlying mechanisms. Consequently, interpretation may be difficult due to dissimilarities in animal models, interventions, and individual properties across animals. Moreover, proarrhythmic effects observed in vivo are often not replicated in corresponding ex vivo preparations during mechanistic studies. We have established a protocol to perform both an in vivo and ex vivo electrophysiological characterization in an arrhythmogenic rat model with heart failure following myocardial infarction. The same animal is followed throughout the experiment. In vivo methods involve intracardiac programmed electrical stimulation and external defibrillation to terminate sustained ventricular arrhythmia. Ex vivo methods conducted on the Langendorff-perfused heart include an electrophysiological study with optical mapping of regional action potentials, conduction velocities, and dispersion of electrophysiological properties. By exploring the retention of the in vivo proarrhythmic phenotype ex vivo, we aim to examine whether the subsequent ex vivo detailed measurements are relevant to in vivo pathological behavior. This protocol can enhance greater understanding of cardiac arrhythmias by providing a standardized, yet adaptable model for evaluating arrhythmogenicity or antiarrhythmic interventions in cardiac diseases.NEW & NOTEWORTHY Rodent models are widely used in arrhythmia research. However, most studies do not standardize clinically relevant in vivo and ex vivo techniques to support their conclusions. Here, we present a comprehensive electrophysiological protocol in an arrhythmogenic rat model, connecting in vivo and ex vivo programmed electrical stimulation with optical mapping. By establishing this protocol, we aim to facilitate the adoption of a standardized model for investigating arrhythmias, enhancing research rigor and comparability in this field.

Modified sympathicotomy in patients with refractory ventricular tachycardia and structural heart disease: a single-center experience

BACKGROUND

Modified cardiac sympathetic denervation (CSD) with stellate ganglion (SG) sparing is a novel technique for cardiac neuromodulation in patients with refractory ventricular tachycardia (VT).

OBJECTIVES

Our aim is to describe the mid- to long-term clinical outcome of the modified CSD with SG sparing in a series of patients with structural heart disease (SHD) and refractory VT.

METHODS

All consecutive patients with SHD and refractory VT undergoing modified CSD were enrolled. Baseline clinical characteristics and periprocedural data were collected for all patients. The primary outcome was any recurrence of sustained VT.

RESULTS

We enrolled 15 patients (age: 69.2 ± 7.9 years; male 100%) undergoing modified CSD. Left ventricular ejection fraction was 37 ± 11% and all patients had an implantable cardiac defibrillator (ICD); the underlying cardiomyopathy was non-ischemic in 73.3% of them. At least one previous ablation had been attempted in 66.6% of cases. The 73.3% of patients underwent bilateral CSD and the mean effective surgical time was 10.8 ± 2.4 min per side; no major periprocedural complication occurred. After a median follow-up time of 15 months (IQR: 8.5-24.5 months), the primary outcome occurred in 47.6% of cases. All patients experienced a reduction of ICD shocks after CSD (3.1 ICD shocks/patient before vs. 0.3 ICD shocks/patient after CSD; p-value: 0.001). Bilateral CSD and a VT cycle length < 340 ms were associated with better outcomes.

CONCLUSIONS

A modified CSD approach with stellate ganglion sparing appears to be safe, fast, and effective in the treatment of patients with SHD and refractory VTs.

Solving the Reach Problem: A Review of Present and Future Approaches for Addressing Ventricular Arrhythmias Arising from Deep Substrate

Ventricular tachycardia (VT) is a significant cause of morbidity and mortality in patients with ischaemic and non-ischaemic cardiomyopathies. In most patients, the primary strategy of VT catheter ablation is based on the identification of critical components of reentry circuits and modification of abnormal substrate which can initiate reentry. Despite technological advancements in catheter design and improved ability to localise abnormal substrates, putative circuits and site of origins of ventricular arrhythmias (VAs), current technologies remain inadequate and durable success may be elusive when the critical substrate is deep or near to critical structures that are at risk of collateral damage. In this article, we review the available and potential future non-surgical investigational approaches for treatment of VAs and discuss the viability of these modalities.

Cardiac sympathetic denervation for untreatable ventricular tachycardia in structural heart disease. Strengths and pitfalls of evolving surgical techniques

Cardiac sympathetic denervation (CSD) is a valuable option in the setting of refractory ventricular arrhythmias in patient with structural heart disease. Since the procedure was introduced for non structural heart disease patients the techniques evolved and were modified to be adopted in several settings. In this state-of-the-art article we revised different techniques, their rationale, strengths, and pitfalls.

Limitations and Pitfalls of Substrate Mapping for Ventricular Tachycardia

The fundamental hypothesis of substrate mapping for scar-mediated ventricular tachycardia is that surrogates of the isthmus can be identified and targeted with ablation during sinus rhythm. These surrogates include electrocardiographic indications for electric discontinuity such as fractionation, split, late, and long potentials, also evident as sites displaying activation slowing. However, ablation strategies targeting these surrogates during sinus rhythm have resulted in unacceptably high rates of clinical failures, promoting the idea that a more widespread ablation may be required. High-resolution mapping technologies provide an opportunity to examine the substrate at greater detail; however, their use has not yet translated into improved clinical outcomes. This may be related to ongoing efforts to examine the same surrogates at higher resolution instead of using high-resolution technologies for discovering new and potentially more specific surrogates. This article reviews common limitations and pitfalls of substrate mapping and discusses new opportunities for high-resolution mapping to increase the accuracy of substrate mapping: 1) multielectrode mapping catheters provide an opportunity to rapidly examine the substrate during electrophysiological conditions that more closely simulate ventricular tachycardia by means of activation from different directions and coupling intervals; 2) electrogram annotation methods based on the maximal negative derivative of the extracellular potential or maximal voltage are often inaccurate in nonuniform anisotropic tissue. The use of multielectrode catheters may improve the accuracy of electrogram annotation by using spatiotemporal dispersion of single-beat acquisitions and a localized indifferent reference; and 3) resetting and entrainment remain important methods for studying re-entry for and guiding ablation.

Mapping strategies for premature ventricular contractions-activation, voltage, and/or pace map

A high premature ventricular contraction (PVC) burden is associated with an increase in cardiovascular mortality and may become clinically apparent through palpitations, reduced physical capacity or PVC-induced cardiomyopathy. Catheter ablation has been shown to be a more effective tool to treat patients with a high PVC burden than medical therapy alone. Current recommendations list catheter ablation as a class I option in patients with symptomatic idiopathic outflow tract PVCs as well as in patients with suspected PVC-induced cardiomyopathy. Careful planning is necessary to maximize efficiency and outcome of the ablation procedure. Prediction of the most likely PVC origin by studying the 12-lead electrocardiogram (ECG) is important. A high burden of spontaneous PVCs is associated with a better outcome during and after the procedure; pharmacological provocation can be performed. Developments in high density mapping systems have greatly advanced accuracy and efficiency of arrhythmia mapping in recent years. Different systems are now available that allow the simultaneous use and integration of different mapping information in an automated manner. Voltage mapping, activation mapping and pace mapping are used in clinical practice today. Activation mapping is used to visualize the area of earliest activation. While it is a very accurate tool, it relies on a high burden of spontaneous PVCs. Pace mapping aims to find the target area by means of stimulation and comparison of paced QRS complexes with the clinical PVC. Today, mostly a combination of both methods is used to maximize procedure outcome and efficiency. While voltage mapping plays a primary role in the mapping of substrate-based sustained arrhythmias in patients with underlying structural heart disease, activation and pace mapping are the methods of choice for PVC mapping.

The challenge of optimising ablation lesions in catheter ablation of ventricular tachycardia

Radiofrequency catheter ablation has become an established treatment for ventricular tachycardia. The exponential increase in procedures has provided further insights into mechanisms causing arrhythmias and identification of ablation targets with the development of new mapping strategies. Since the definition of criteria to identify myocardial dense scar, borderzone and normal myocardium, and the description of isolated late potentials, local abnormal ventricular activity and decrementing evoked potential mapping, substrate-guided ablation has progressively become the method of choice to guide procedures. Accordingly, a wide range of ablation strategies have been developed from scar homogenization to scar dechanneling or core isolation using increasingly complex and precise tools such as multipolar or omnipolar mapping catheters. Despite these advances long-term success rates for VT ablation have remained static and lower in nonischemic than ischemic heart disease because of the more patchy distribution of myocardial scar. Ablation aims to deliver an irreversible loss of cellular excitability by myocardial heating to a temperatures exceeding 50°C. Many indicators of ablation efficacy have been developed such as contact force, impedance drop, force-time integral and ablation index, mostly validated in atrial fibrillation ablation. In ventricular procedures there is limited data and ablation lesion parameters have been scarcely investigated. Since VT arrhythmia recurrence can be related to inadequate RF lesion formation, it seems reasonable to establish robust markers of ablation efficacy.