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 general population and cardiac electrical instability is a prime suspect cause. Our study shows that girls with Rett syndrome had significantly lower heart rate variability (marker of autonomic disarray) and longer corrected QT intervals compared with an age-matched group of healthy girls. These abnormalities increased with advancing stages of the syndrome. These findings suggest a possible role of cardiac dysfunction in the sudden death associated with Rett syndrome.