Electrical storm in patients with transvenous implantable cardioverter-defibrillators: incidence, management and prognostic implications.
OBJECTIVE
The purpose of this study was to determine the precise incidence, therapeutic options and prognostic implications of electrical storm in patients with transvenous implantable cardioverter-defibrillator (ICD) systems.


BACKGROUND
Approximately 50% to 70% of patients treated with an ICD receive appropriate device-based therapy within the first 2 years. Most arrhythmic events require only one appropriate ICD firing for termination. However, some patients receive multiple appropriate shocks during a short period of time, a condition referred to as "arrhythmic or electrical storm."


METHODS
This prospectively designed observational study comprised 136 recipients of transvenous ICDs who were followed for 403+/-242 days. Electrical storm was defined as ventricular tachycardia or fibrillation resulting in device intervention > or = 3 times during a single 24-h period.


RESULTS
During follow-up, 57/136 patients (42%) received appropriate ICD therapy. Electrical storm occurred in 14/136 patients (10%) at an average of 133+/-135 days after ICD implantation. The mean number of arrhythmic episodes constituting electrical storm was 17+/-17 (range: 3 to 50; median 8) per patient. In 12 patients, electrical storm required hospital admission. The arrhythmia cluster could be terminated by a combined therapy with beta-blockers and intravenous amiodarone whereas class I antiarrhythmic drugs were only occasionally successful. The cumulative probability of survival as estimated by the Kaplan-Meier method showed that patients with an episode of electrical storm did not have a worse outcome compared to those without such an event.


CONCLUSIONS
Electrical storm represents a frequent event in patients treated with modern ICDs. It occurs most commonly late after ICD implantation and can be managed by combined therapy with beta-blockers and amiodarone. Electrical storm does not independently confer increased mortality.
Credner
S C
SC
Department of Internal Medicine, JW Goethe University, Frankfurt, Germany.
Klingenheben
T
T
Mauss
O
O
Sticherling
C
C
Hohnloser
S H
SH
D000328:Adult; D000368:Aged; D017704:Baroreflex; D017147:Defibrillators, Implantable; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012008:Recurrence; D017180:Tachycardia, Ventricular / Q000503:physiopathology / Q000628:therapy*; D016896:Treatment Outcome; D014693:Ventricular Fibrillation / Q000503:physiopathology / Q000628:therapy*