Clinical characteristics of electrical storm in patients with early repolarization syndrome.

ABSTRACT

BACKGROUND: Early repolarization syndrome (ERS) is an idiopathic ventricular fibrillation (VF) associated with inferolateral J waves. While electrical storm (ES) in ERS is not rare, their characteristics and risk factors are not fully understood. OBJECTIVE: This study aimed to clarify the significance of ES in ERS. METHODS: We evaluated 44 patients with ERS who experienced VF/sudden cardiac death or arrhythmic syncope. We assessed clinical characteristics to identify the risk factors for ES. RESULTS: In total, 13 patients (30%) experienced ES (ES group). Of these, 11 patients (85%) experienced ES during the acute phase of initial VF episodes and 2 patients (2%) experienced ES during follow-up. VF associated with ES occurred during therapeutic hypothermia in 6 of 13 patients (46%). The J-wave voltage during therapeutic hypothermia was higher in the ES group than that in the patients without ES. Isoproterenol was used in 5 patients (38%), which decreased J-wave voltage and relieved ES. Among the clinical markers, shorter QT and QTp intervals (the interval from QRS onset to the peak of T wave), pilsicainide-induced ST elevation, and high scores on the Shanghai Score System were associated with ES. Although pilsicainide induced ST elevation in 6 of 34 patients (18%), spontaneous Brugada electrocardiographic patterns did not appear to be associated with VF. Therapeutic hypothermia was also a risk factor for acute phase ES. CONCLUSION: Patients with ERS in the ES group frequently had short QT and QTp intervals, pilsicainide-induced ST elevations, and high Shanghai Score System scores. Therapeutic hypothermia was also associated with acute phase ES.