Clinical Characteristics of Electrical Storm in Patients With Early Repolarization Syndrome.

BACKGROUND: Early repolarization syndrome (ERS) is an idiopathic ventricular fibrillation (VF) associated with inferolateral J waves. While electrical storms (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 experienced ES during the acute phase of initial VF episodes, and 2 patients experienced ES during follow-up. VF associated with ES occurred during therapeutic hypothermia in 6 of 13 patients. The J wave voltage during therapeutic hypothermia was higher in the ES group than that in the non-ES group. Isoproterenol was used in 5 patients, 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 points on the Shanghai Score System (SSS) were associated with ES. Although pilsicainide induced ST elevation in 6 patients, spontaneous Brugada electrocardiographic patterns did not appear to be associated with VF. Therapeutic hypothermia was also a risk factor for acute-phase ES.

CONCLUSIONS: Patients with ERS in the ES group frequently had short QT and QTp intervals, pilsicainide-induced ST elevations, and high SSS scores. Therapeutic hypothermia was also associated with acute phase ES.