Prevalence, Predictors, and Mortality Significance of the Causative Arrhythmia in Patients with Electrical Storm

Abstract

VF is the causative arrhythmia for a sizable proportion of patients with ES. The initial ICD indication, coronary artery disease, and amiodarone therapy are predictors of the causative arrhythmias in ES. There does not appear to be any mortality difference between ES patients with VT and VF, but mortality is increased in patients with ES versus control ICD patients without ES.

Electrical Storm in the Era of Implantable Cardioverter Defibrillators

“…Among patients whose ICDs were placed for prior VT, 64% of ES episodes were caused by VT compared to only 28% by VF. For those patients whose ICDs were placed for prior VF, 45% of ES episodes were caused by VF and only 14% by VT. 20 Analysis of MADIT II patients with electrical storm revealed similar findings. Of 12 patients who had a prior episode of VT, 11 subsequently had VT as their initial rhythm in their ES.…”

“…Lack of a consensus definition for ES, as well as differences in ICD implant indications, concomitant medical therapy, and follow-up periods all contribute to the disparate reported incidence rates of 10-60% in the secondary prevention population. Using the definition of >/= 3 VF/VT episodes in 24-hours requiring device intervention, the incidence of ES is approximately 10-28% over a 1-3 year follow-up period when ICDs are placed for secondary prevention of cardiac arrest 1,2,8,[10][11][12][13][14][15][16][17][18][19][20][21] . From a more consistent study population in the Multicenter Automatic Defibrillator Implantation Trial II (MADIT II), the reported incidence of electrical storm in a primary prevention ICD population is substantially lower at 4% 13 18 The reported 70% identification of an acute cause in this series is disparate from the larger published trials but does point out the need to take a thorough history when presented with a storm patients to effectively treat the current storm episode and prevent further ES.…”

“…VF alone accounts for 1%-21% of ES, mixed VT/VF 3%-14% and polymorphic VT 2-8%. 20 , reported a significant correlation between the initial arrhythmia that led to ICD implantation and the arrhythmia responsible for ES. Among patients whose ICDs were placed for prior VT, 64% of ES episodes were caused by VT compared to only 28% by VF.…”

“…Patients with a prior isolated episode of VF also had this rhythm as their initial rhythm in the first ES. 13,20 The predilection for patients with coronary artery disease (CAD) and previous VT to have storm caused by monomophic VT, taken together with the influence of storm on future survival (discussed later), raises the question as to whether medical therapy alone is an aggressive enough strategy for prevention of ES in patients with ischemic cardiomyopathy who experience appropriate ICD therapies for VT. Whether or not more definitive substrate modification with re-vascularization or catheter ablation of VT in select patients may prove an effective means of reducing long-term morbidity and mortality in patients with a history of ES or those at significant risk for future storm awaits further data specifically addressing this topic.…”

Intensive management of electrical storm and incessant ventricular arrhythmias

“…The results of large clinical trials show that the ES developed in ICD patients may be a strong predictor of arrhythmic and nonarrhythmic death, and also rehospitalization [7,8,11,23,24].…”