Patients with structural heart disease, predictably form the bulk of the cases of VES. However, individuals with structurally normal hearts can also be predisposed to VES owing to genetic arrhythmia syndromes such as catecholaminergic polymorphic VT (CPVT), Brugada syndrome, long QT syndrome (LQTS).[16–18] The term VES is quite apt in a way that it mandates a perfect storm of several factors. Ventricular electrical storm is governed by a complex interplay of the following elements (Figure 1):
The triad of ventricular electrical storm consists of a complex interplay between an arrhythmogenic substrate, autonomic imbalances, and acute triggers. Some examples of each are enlisted in this figure.
Presence of a susceptible electrophysiologic substrate:
In ICM, NICM or other forms of cardiomyopathy, scarred myocardium provides the anatomical basis for re-entrant VA.
Inciting factors may include ischaemia, decompensated heart failure, infections, endocrine emergencies, electrolyte derangements, and antiarrhythmic drug non-compliance. At the cellular level, calcium mishandling and disorders of protein phosphorylation have also been proposed as potential mechanisms for arrhythmia-induced cardiomyopathy.[21–23] While addressing a reversible aetiology is the prudent approach, per prior studies, a reversible cause cannot be determined in the majority of cases.
Certain chronic cardiac conditions may portend a neural remodelling, which involves a decrease in parasympathetic input, and eventual sympathetic hyperinnervation. A temporal increase in sympathetic activity may drive the initiation of the arrhythmic episode. Furthermore, ICD shocks increase the adrenergic tone, creating a vicious cycle that may lead to VES.
Additionally, genetic arrhythmia syndromes may provide the necessary substrate for VES, even in the absence of structural heart disease. Fascinatingly, causative genes of genetic conditions such as Brugada syndrome, and early repolarization have been discovered in patients developing VES from other causes such as ischaemia. This association begs the intriguing question: Is VES just a phenotypic culmination of several disease processes, or is it a separate entity by itself? The answer remains elusive.
Europace. 2020;22(12):1768-1780. © 2020 Oxford University Press
Copyright 2007 European Heart Rhythm Association of the European Society of Cardiology (ESC). Published by Oxford University Press. All rights reserved.