In-Hospital Electrical Storm in Acute Myocardial Infarction ― Clinical Background and Mechanism of the Electrical Instability ―

BACKGROUND: Recurrent ventricular tachycardia (VT) and fibrillation (VF), the so-called "electrical storm" (ES) occurs at various stages of acute myocardial infarction (AMI), but its incidence, background, and short-term prognosis remain unclear. Methods and Results: A retrospective observational study was performed using the registry database of the Tokyo CCU Network. The individual data of 6,003 patients with AMI during 2011-2012 was corrected. ES was defined as more than 3 episodes of sustained VT/VF during a 24-h period as first documented after hospitalization. ES occurred in 55 patients after admission (0.9%). The ES(+) group had more severe heart failure (Killip class >III), more extensive MI (peak-CK), greater inflammatory reaction (CRP), history of diabetes, and more frequent application of hemodialysis as compared with the ES(-) group (n=5,865). When the ES patients were divided into Early-ES (n=37: ES occurred ≤48 h after the onset of MI) and Late-ES (n=15 >48 h after onset of MI) groups, logistic regression analysis revealed that Early-ES was associated with severity of MI, whereas Late-ES was related to systemic disorders, including inflammation, renal dysfunction, or diabetes. Late-ES was an independent predictor of in-hospital death. CONCLUSIONS: In-hospital ES was a rare clinical manifestation of AMI. The features and background of the ES varied as time elapsed after admission for MI.