Is there increased sympathetic activity in patients with mitral valve prolapse?

The aim of this study was to investigate autonomic nervous system tone in patients with mitral valve prolapse (MVP). Heart rate variability (HRV) was assessed from 24-hour ambulatory Holter recordings in 28 patients with primary MVP and in 28 age and sex matched normal control subjects in a drug-free state. Sixteen of the MVP patients were symptomatic and 12 asymptomatic. Spectral HRV was calculated in terms of low (LF: 0.06-0.15 Hz) and high (HF: 0.15-0.40 Hz) frequency components using fast Fourier transform analysis, and the ratio LF/HF was calculated. Spectral analysis of HRV showed that the MVP patients, taken as a single group, had lower HF and LF and a higher LF/HF ratio than the controls. No significant difference in HRV was found between the 16 symptomatic and the 12 asymptomatic patients, but the symptomatic patients had a significantly higher LF/HF ratio than the controls. Our observations suggest that, during normal daily activities, patients with MVP experience a significant deviation in autonomic nervous system tone with predominance of the sympathetic branch. This predominance is more marked in symptomatic patients.