Predictors of electrical storm recurrences in patients with implantable cardioverter-defibrillators

Aims To determine prevalence and predictors of electrical storm recurrences (ES-Rs) in patients with implantable cardioverter-defibrillators (ICDs) as electrical storms (ESs) represent serious clinical events carrying a high risk of mortality. Methods and results Single-centre study analysing data of consecutive patients receiving an ICD between 1993 and 2008. Electrical storm was defined as >= 3 separate ventricular tachyarrhythmic (VT/VF) episodes <= 24 h. Nine hundred and fifty-five patients [mean left ventricular ejection fraction (LVEF) 35.7 +/- 15.6%] were prospectively followed for 54.2 +/- 35.5 months. In 274 of 955 patients (28.7%), 2871 VT/VF episodes were observed. One hundred and fifty-three ES episodes occurred in 63 of 955 patients (6.6%). Thirty-two of 63 patients (50.8%) experienced >= 2 ES episodes. Twenty-six of 32 patients (81.2%) with ES-Rs experienced the second ES episode within 1 year after the initial event. Cox regression analysis identified an LVEF <= 30% (OR 2.2; 95% CI 1.021-4.856; P = 0.044) and a patient's age > 65 years (OR 3.5; 95% CI 1.207-10.176; P = 0.021) to be predictive for ES-Rs. Patients with angiotensin-converting enzyme (ACE) inhibitor therapy were less likely to experience ES-Rs (OR 0.39; 95% CI 0.187-0.817; P = 0.013). Conclusions Electrical storm events are not rare in a 'real-world' patient population with ICDs (6.6% in 4.5 years). The risk for ES-Rs, especially within the first year after the initial event, is high. Left ventricular ejection fraction <= 30%, age > 65 years, and a lack of ACE inhibitor therapy are independent predictors of ES-R.