Abstract 2823: Association of Early Repolarization With Arrhythmic Events in Short QT Syndrome
Background: Short QT syndrome (SQTS) is a very rare disease, characterized by an abnormally short QT interval and sudden death. Due to the limited number of cases, the characteristics of SQTS are not well understood. Recent evidence that early repolarization is associated with idiopathic ventricular fibrillation and the QT interval is short in patients with early repolarization suggests an association between early repolarization and short QT interval.
Methods: This cooperative study included 1) patients with SQTS referred to our institutions and 2) patients with SQTS in the literature. Patients with Brugada type ST-segment elevation were excluded.
Results: We identified 40 patients with SQTS: 13 patients in our institutions and 27 patients in the literature. Clinical characteristics were similar between patients in our institutions and those in the literature. There were 23 patients (58%) with symptoms including 15 patients with cardiac arrest (sudden death, N=3; resuscitated, N=12) and 8 with syncope. Early repolarization occurred in 24 patients (60%). Early repolarization was present in the inferior leads in 11 patients, in the lateral leads in 4 patients, and in both inferior and lateral leads in 9 patients. Of 8 probands with early repolarization genetically screened, mutations were identified in 3 patients (KCNQ1, N=1; KCNH2, N=2). A history of arrhythmia events was more common in patients with early repolarization than those without, although the QT or QTc intervals were similar (Table⇓). There was no difference in gender, age, family history, ion channel mutations, or inducibility of ventricular arrhythmia between patients with early repolarization and those without. In multivariable models, early repolarization was associated with high incidence of arrhythmic events (P=0.003).
Conclusions: There was an increased prevalence of early repolarization in patients with SQTS. Early repolarization may be useful to identify risk of cardiac events in SQTS.