Risk factors and prognostic role of an electrical storm in patients after myocardial infarction with an implanted ICD for secondary prevention.

Abstract

IntroductionThe aim of our study was to determine the risk factors for electrical storm (ES) and to assess the impact of ES on the long-term prognosis in patients after myocardial infarction (MI) with an implantable cardioverter-defibrillator (ICD) for secondary prevention of sudden cardiac death (SCD).Material and methodsWe retrospectively analyzed 416 patients with coronary artery disease after MI who had an implanted ICD for secondary prevention of SCD. Fifty (12%) patients had one or more incidents of an electrical storm – the ES (+) group. We matched the reference group of 47 patients from 366 ES (–) patients.ResultsWe analyzed 3,408 episodes of ventricular arrhythmias: 3,148 ventricular tachyarrhythmic episodes in the ES (+) group (including 187 episodes of ES) and 260 in the ES (–) group. Multivariate logistic regression showed that inferior wall MI (RR = 3.98, 95% CI: 1.52–10.41) and the absence of coronary revascularization (RR = 2.92, 95% CI: 1.18–7.21) were independent predictors of ES (p = 0.0014). During 6-year observation of 97 patients, there were 39 (40%) deaths: 25 (50%) subjects in the ES (+) group and 14 (30%) in the ES (–) group (p = 0.036). Independent predictors of death were: the occurrence of ES (HR = 1.93), older age (HR = 1.06), and lower left ventricular ejection fraction (HR = 0.95) (for all p < 0.001).ConclusionsElectrical storm in patients after MI with ICD for secondary prevention is a relatively common phenomenon and has a negative prognostic significance. Myocardial infarction of the inferior wall and the absence of coronary revascularization are predisposing factors for the occurrence of an ES.