Original Article Heart Rate Variability in Myotonic Dystrophy Type 1 Patients

and in the sinoatrial node associated to myocyte hypertrophy7. Patients with greater skeletal muscle impairment are older and experience heart problems more frequently8. The autonomic nervous system plays a crucial role in heart rate (HR) modulation. A decrease in its variability is a predictor of morbidity and mortality9,10. Earlier research found that healthy women showed greater vagal dominance over HR, which seems to account for their enhanced cardioprotection compared to men, although these differences decrease with age11. The study of heart rate variability (HRV) has therefore been proposed as a simple, inexpensive and non-invasive method that provides information on neurocardial integrity. A number of investigations on the overall function of the autonomic nervous system in patients with MD show that the presence of autonomic neuropathy is highly unlikely1,12,13. However, studies on autonomic modulation of HR in patients with MD have obtained conflicting results14-18. The present study aimed to evaluate the possible differences in autonomic modulation of HR between the sexes for patients with MD and healthy individuals in different body positions and the influence of interaction between sex and disease on autonomic modulation of HR in different body positions