Recent insights into mechanisms and clinical approaches to electrical storm.

Electrical storm, characterized by repetitive ventricular tachycardia/fibrillation (VT/VF) over a short period, is becoming commoner with widespread use of implantable cardioverter-defibrillator (ICD) therapy. Electrical storm, sometimes called "arrhythmic storm" or "VT-storm", is usually a medical emergency requiring hospitalization and expert management, and significantly affects short- and long-term outcomes. This syndrome typically occurs in patients with underlying structural heart disease (ischemic or non-ischemic cardiomyopathy) or inherited channelopathies. Triggers for electrical storm should be sought but are often unidentifiable. Initial management is dictated by the hemodynamic status, while subsequent management typically involves ICD interrogation and reprogramming to reduce recurrent shocks, identification/management of triggers like electrolyte abnormalities, myocardial ischemia, or decompensated heart failure, and antiarrhythmic-drug therapy or catheter ablation. Sympathetic nervous system activation is central to the initiation and maintenance of arrhythmic storm, so autonomic modulation is a cornerstone of management. Sympathetic inhibition can be achieved with medications (particularly beta-adrenoreceptor blockers), deep sedation, or cardiac sympathetic denervation. More definitive management targets the underlying ventricular arrhythmia substrate to terminate and prevent recurrent arrhythmia. Arrhythmia targeting can be achieved with antiarrhythmic medications, catheter ablation or more novel therapies such as stereotactic radiation therapy that targets the arrhythmic substrate. Mechanistic studies point to adrenergic activation and other direct consequences of ICD-shocks in promoting further arrhythmogenesis and hypocontractility. Here, we review the pathophysiologic mechanisms, clinical features, prognosis, and therapeutic options for electrical storm. We also outline a clinical approach to this challenging and complex condition, along with its mechanistic basis.