Abstract 2764: Clinical Phenotype of Japanese LQT3 Form of Congenital Long QT Syndrome by Location of Mutation from Japanese Multicenter Registry
Background: Effects of location of mutation on clinical phenotype in a large scale of patients with LQT3 syndrome are unclear.
Methods and Results: Forty-nine patients (male=30, proband=25) with an SCN5A mutation were retrospectively studied from a Japanese multicenter registry and divided into patients with mutations located in the transmembrane (TM) portion and the non-transmembrane (non-TM) portion. Although there was no significant difference in the QTc interval between the two groups (478±78 vs. 508±37ms; p=0.079), both cumulative cardiac event rates and lethal cardiac event (VF and/or aborted cardiac arrest) rates were significantly higher in the TM group (Figure⇓, p=0.006, p=0.007, respectively). By performing the multivariate analysis, longer QTc interval and the TM group was an independent risk factor for cardiac events (QTc≥500ms vs. QTc<500ms; hazard ratio=5.612, p=0.05, TM vs. non-TM; hazard ratio=15.234, p=0.009).
Conclusion: In this multicenter study, Japanese LQT3 patients with mutations located in the transmembrane portion were at higher risk for cardiac events.