sinus arrhythmia in a child

my daughter was diagnosed as having sinus arrhythmia last year and i was told not to worry that it is common in children.  I am a mitral valve prolapse sufferer with symptoms and i worry that this is an early sign that she will be a mvp sufferer as well.  She is now 9 years old, and everything i have read about this says it is common in babies and the elderly but i have read nothing about it being common in children.  Is this something that i should just ignore or regularly have checked.

[Cleveland Clinic, MD]

Not only is sinus arrhythmia common in children it is common in teenagers, adults, the elderly and babies - in another words everyone!  AS a matter of fact more sinus arrhythmia is a sign of good health.  So not to fear this is not a sign of MVP.