BACKGROUND: The studies on heart rate variability (HRV), a key predictor of 
all-cause mortality, in Marfan syndrome (MS), up to now have not been reported, 
especially in patients with FBN1 mutations.
METHODS: Among 18 MS patients with the phenotype of MS meeting inclusion 
criteria 15 have had a FBN1 gene mutation. Short electrocardiography records 
were taken in the supine position and during orthostatic tests. The control 
group consisted of 30 apparently healthy nonathletes matched by age and gender.
RESULTS: Heart rates in MS patients with the FBN1 mutation were increased in 
both the supine position and orthostatic test (p < 0.001). Most of the 
time-domain (standard deviation, pNN50) and frequency-domain (total power, very 
low, low, and high frequency) parameters of HRV were significantly reduced in 
the MS patients (p < 0.001).
CONCLUSIONS: A marked decrease in HRV, documented in the study, may be an 
important clinical feature in MS patients with confirmed FBN1 gene mutations.