Heart rate variability assessment in patients with mitral valve prolapse syndrome

Mitral valve prolapse (MVP) is a common valvular abnormality especially in young female subjects. Recently, Boudulas had classified the patients with MVP into two types: the 1st type is MVP-anatomic (MVPa) with valvular malfunction and the 2nd MVP-syndrome (MVPs) without valvular disease. In the 2nd type, several authors have reported the occurrence of functional abnormalities of neuroendocrine or autonomic systems. Also, the syncope called 'neuromediated' has been found and is probably associated with modification of the autonomic nervous system. To understand the role of the autonomic nervous system, 39 female patients with MVPs (group 1) and 24 normal females as control group (group 2) were evaluated by a spectral analysis of heart rate variability (HRV) in time and frequency domains. The analysis between the two groups showed a low vagal tone in group 1 resulting in a lower high-frequency normalized unit (HF-NU) in comparison with the control group 2 (p <0.03). Group 1 was divided into two subgroups with and without syncope. The analysis of HRV by Anova indicated no differences for all parameters between the two subgroups of MVPs patients. These results demonstrate that (1) MVPs has a low vagal tone; (2) the syncope in MVPs could not be only in relation to the autonomic nervous system malfunction, but probably other causes underlined this phenomenon.