Contractility Dispersion in Long QT Syndrome

Background: Previous studies, using M mode echocardiography, provided unexpected evidence of a mechanical
alteration in patients with long QT syndrome. The aim of this study was to evaluate entire left ventricular
(LV) wall motion characteristics in patients with long QT syndrome using tissue Doppler imaging.
Methods: We enrolled 17 patients with congenital long QT syndrome [11 female and 6 male], aged 21 to 45
years. 10 subjects without cardiac disease were also selected as a control group. Two-dimensional tissue Doppler
imaging (TDI) recording of the LV was obtained from the basal and mid-segments from apical four-chamber,
two-chamber, and long-axis views. ‘Myocardial Contraction Duration’ [MCD] was defined as the time from
start of R wave on ECG to end of S wave on TDI. MCD was measured in the six LV wall positions: septal, anteroseptal,
lateral, inferior, posterior and anterior positions.
Results: LV contractility dispersion was significantly greater in long QT syndrome patients compared to control
group [0.051 ± 0.011 vs. 0.016 ± 0.06; P < 0.001].
Conclusion: Our study evaluated left ventricular dispersion of contractility duration in patients with long QT
syndrome. This mechanical dispersion may be a reflection of the inhomogeneity of repolarisation in the long
QT syndrome.