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Electrical Storm Presages Nonsudden Death. The Antiarrhythmics vs. Implantable Defibrillators (AVID) Trial - AVID Electrical Storm Substudy
Description:
Electrical Storm Presages Nonsudden Death. The Antiarrhythmics vs. Implantable Defibrillators (AVID) Trial.
Hypothesis:
What is the prognostic significance of electrical storm (>/= 3 discrete episodes of ventricular tachycardia [VT] or ventricular fibrillation [VF] within 24 hours) among recipients of an ICD?
Study Design
Study Design:
Patients Enrolled: 457
Drug/Procedures Used:
A cardiovertor/defibrillator (ICD) was implanted in 457 patients with ventricular fibrillation (VF) or ventricular tachycardia (VT) associated with syncope or hemodynamic compromise and an ejection fraction <0.40. Survival during a mean of 31 months of follow-up was compared among 90 patients who had an electrical storm, 184 patients who had VT/VF without electrical storm and 183 patients who did not have VT/VF.
Principal Findings:
Patients who had VT/VF (with or without electrical storm) during follow-up had a lower ejection fraction than the other patients (0.29 vs. 0.35) and were less likely to have undergone revascularization after the index arrhythmia. Electrical storm occurred at a mean of 9 months after ICD implantation. The death rate was higher among patients with electrical storm (38%) than among patients with VT/VF without electrical storm (15%) and the remaining patients (22%). The most common type of death was nonsudden cardiac death. Electrical storm was independently associated with death (relative risk 2.4) but VT/VF without electrical storm was not. The risk of death was greatest during the first 3 months after electrical storm (relative risk 5.4).
Among patients with an ICD, electrical storm is a marker for subsequent nonsudden cardiac death, independent of other variables such as ejection fraction.
Interpretation:
It is unclear whether electrical storm is a direct contributor to subsequent nonsudden cardiac death (perhaps by causing myocardial injury) or simply a marker of more severe underlying heart disease. An implication of the former circumstance is that prevention of electrical storm with prophylactic antiarrhythmic drug therapy may improve prognosis. On the other hand, if electrical storm is a marker of more severe disease, it is possible that aggressive optimization of ventricular function might improve prognosis. However, whether survival after electrical storm can be improved by these interventions remains to be determined.
References:
1. Exner DV, Pinski SL, Wyse G, et al. and the AVID Investigators. Circulation 2001;103:2066-71.
Keywords: Prognosis, Risk, Tachycardia, Ventricular, Follow-Up Studies, Ventricular Fibrillation, Syncope, Ventricular Function, Defibrillators, Implantable, Hemodynamics
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