Temporal repolarization lability differences among genotyped patients with the long QT syndrome.

The investigators sought to test whether certain long QT syndrome (LQTS) mutations are associated with increased repolarization lability and whether repolarization lability (quantified by the QT variability index [QTVI]) is increased in patients with LQTS compared with controls. In 32 genotyped patients with LQTS type 1 (LQT1), 32 genotyped patients with LQTS type 2 (LQT2), and 32 controls, the QTVI was increased in patients with LQT2 (-0.973 +/- 0.394, p = 0.01 vs controls) and in patients with LQT1 with mutations other than KCNQ1-FIN (-0.942 +/- 0.264, p = 0.04 vs controls) but was similar between the KCNQ1-FIN group and controls.