Ventricular arrhythmia storms in postinfarction patients with implantable defibrillators for primary prevention indications: a MADIT-II substudy.
BACKGROUND
Much of prognostic implications of ventricular arrhythmia storms remain unclear.


OBJECTIVE
We evaluated the risk associated with electrical storm in patients with defibrillators in the Multicenter Automatic Defibrillator Implantation Trial II (MADIT-II) study.


METHODS
Electrical storm was defined as > or =3 episodes of ventricular tachycardia (VT) or ventricular fibrillation (VF) in 24 hours.


RESULTS
Of the 719 patients who received internal cardiac defibrillator (ICD) implants and had follow-up in the MADIT-II, 27 patients (4%) had electrical storm, 142 (20%) had isolated episodes of VT/VF, and the remaining 550 patients had no ICD-recorded VT events. Baseline clinical characteristics among the groups were similar. Patients who experienced electrical storm had a significantly higher risk of death. After adjustments for relevant clinical covariates, the hazard ratio (HR) for death in the first 3 months after the storm event was 17.8 (95% confidence interval [CI] 8.0 to 39.5, P <.01) in comparison with those with no VT/VF. This risk continued even after 3 months for those with electrical storm (HR of 3.5, 95% CI 1.2 to 9.8, P = .02). Study patients with isolated VT/VF episodes also were at an increased risk of dying (HR = 2.5, 95% CI 1.5 to 4.0, P <.01) when compared with patients without VT/VF episodes. Statistically significant predictors of electrical storm were interim postenrollment coronary events (myocardial infarction or angina) HR 3.1 (95% CI 1.2 to 8.1, P = .02) and isolated VT or VF HR 9.2 (95% CI 4.0 to 20.9, P <.01).


CONCLUSIONS
Postinfarction patients with severe left ventricular dysfunction in whom electrical storm developed have significantly higher mortality than patients with only isolated VT/VF as well as those without any episodes of VT/VF. Patients who experienced postenrollment ventricular arrhythmias and/or interim coronary events during follow-up were at higher risk for VT/VF storms.
Sesselberg
Henry W
HW
Department of Medicine, Cardiology Unit, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA.
Moss
Arthur J
AJ
McNitt
Scott
S
Zareba
Wojciech
W
Daubert
James P
JP
Andrews
Mark L
ML
Hall
W Jackson
WJ
McClinitic
Benjamin
B
Huang
David T
DT
D000368:Aged; D017147:Defibrillators, Implantable; D005260:Female; D006333:Heart Failure; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications / Q000503:physiopathology*; D011322:Primary Prevention; D011446:Prospective Studies; D012307:Risk Factors; D013318:Stroke Volume; D017180:Tachycardia, Ventricular / Q000209:etiology* / Q000517:prevention & control; D013997:Time Factors; D014693:Ventricular Fibrillation / Q000209:etiology* / Q000517:prevention & control