[Electrical storm in ICD patients: prevention and treatment]

Medical progress and demographic changes cause a continuous increase in patients with implantable cardioverter-defibrillators (ICD). Up to one third of patients with ICDs for secondary prevention and half of the patients with previous electrical storm (ES) will suffer from (further) ESs. When multiple ICD shocks are reported by patients (ICD storm), appropriate, inappropriate and phantom shocks have to be distinguished. Reported shocks without clinical correlates (phantom) often affect patients suffering from posttraumatic stress syndrome after an ICD storm. Approximately one third of all ICD shocks are inappropriate, most often due to supraventricular tachycardia with fast atrioventricular (AV) nodal conduction or lead failure. Within 10 years after implantation lead failure can be detected in up to 20 % of cases and approximately one third of these failures are only seen after inappropriate ICD shocks. Furthermore, inappropriate shocks are due to oversensing of far field atrial electrograms, T-waves, diaphragmatic potentials and electrical noise.Appropriate ICD shocks can rarely also be stimulated by the proarrhythmogenicity of lead implantation or ICD programming. Modifications of the waiting period to therapy, time to detection, detection window, antitachycardia pacing (ATP) stimulation and supraventricular discrimination algorithms may minimize ICD shocks. Some stimulation algorithms may improve the hemodynamic stability during ES. In addition to ventricular ablation, blockade of the sympathetic autonomic nervous system and antiarrhythmic treatment are the main pillars of ES treatment. The best ES prevention, however, is optimized heart failure treatment, especially when a cardiac resynchronization with defibrillator (CRT-D) system is implanted.