Contemporary Management of Electrical Storm

Cardiac electrical storm (ES) is characterised by three or more discrete episodes of ventricular arrhythmia within 24hours, or incessant ventricular arrhythmia for more than 12hours. ES is a distinct medical emergency that portends a significant increase in mortality risk and often presages progressive heart failure. ES is also associated with psychological morbidity from multiple implanted cardioverter defibrillator (ICD) shocks and exponential health resource utilisation. Up to 30% of ICD recipients may experience storm in follow-up, with the risk higher in patients with a secondary prevention ICD indication. Storm recurs in a high proportion of patients after an initial episode, and multiple storm clusters may occur in follow-up. The mechanism of storm remains elusive but is likely influenced by a complex interplay of inciting triggers (e.g., ischaemia, electrolyte disturbances), with autonomic perturbations acting on a vulnerable structural and electrophysiologic substrate. Triggers can be identified only in a minority of patients. An emergent treatment approach is warranted, if possible with emergent transfer to a high-volume centre for ventricular arrhythmia management with a multi-modality approach including ICD reprogramming, sympathetic blockade (sedation, intubation, ventilation, beta blockers), and anti-arrhythmic drugs, and adjunctive intervention techniques, such as catheter ablation and neuraxial modulation (e.g., thoracic epidural anaesthesia, stellate ganglion block). Outcomes of catheter ablation of ES are excellent with resolution of storm in over 90% of patients at 1year with a low complication rate (∼2%). ES may occur in the absence of structural heart disease in the context of channelopathies, Brugada syndrome, early repolarisation and premature ventricular contraction-induced ventricular fibrillation. There are unique treatment approaches to these conditions that must be recognised. This state-of-the-art review will summarise the incidence, mechanism, and multi-modality treatment of ES in the contemporary era.