Reduced heart rate variability in patients affected with Rett syndrome. A possible explanation for sudden death

Incidence of sudden death in Rett syndrome is greater than that of the gene ral population and cardiac electrical instability is a prime suspect cause. Our study shows that girls with Rett syndrome had significantly lower hear t rate variability (marker of autonomic disarray) and longer corrected QT i ntervals compared with an age-matched group of healthy girls. These abnorma lities increased with advancing stages of the syndrome. These findings sugg est a possible role of cardiac dysfunction in the sudden death associated w ith Rett syndrome.