Role of electrical storm as a mortality and morbidity risk factor and its clinical predictors: a meta-analysis

Electrical storm (ES) is a devastating and life-threatening event in clinical practice, but its real weight as a risk factor and its clinical predictors remain unclear. Our objective was to evaluate ES as a mortality and morbidity risk factor and to define the clinical variables associated with ES. The meta-analysis was performed according to the PRISMA guidelines. At the end of the selection process, 13 studies were collected and included in the quantitative analysis. Mortality and morbidity due to ES were assessed. The most acknowledged ES predictors were taken into account in separate sub-analyses. The whole cohort included 5912 patients (857 with ES). Risk of death was increased in the ES group [risk ratio (RR) 3.15; 95% confidence interval (CI) 2.22-4.48]. Electrical storm was also associated with increased composite risk of all-cause death, cardiac transplantation, and hospitalization for acute heart failure (RR 3.39; 95% CI 2.31-4.97). These results were confirmed by comparing the ES group with patients with or without previous unclustered episodes of ventricular arrhythmias. Moreover, implantable cardioverter-defibrillator (ICD) for secondary prevention, lower ejection fraction, monomorphic ventricular tachycardia as triggering arrhythmia, and class I anti-arrhythmic drugs therapy were all associated with ES. Electrical storm is a strong mortality risk factor and it is associated with an increased combined risk of death, heart transplantation, and hospitalization for heart failure. Implantable cardioverter-defibrillator for secondary prevention, monomorphic ventricular tachycardia as triggering arrhythmia, lower ejection fraction, and class I anti-arrhythmic drugs therapy are all associated with ES and could be used to define specific populations with higher risk to develop ES.