Studies in patients with mitral valve prolapse syndrome (MVPS) have shown a variety of forms of autonomic dysfunction, which require further investigation.

The study group consisted of 29 male MVP patients, aged 23±3 years, and 17 male healthy controls, aged 25±2 years. The patients and the control subjects were matched for age and sex. All study subjects underwent a complete echocardiographic examination, and were free of other organic heart diseases and arrhythmia. In a prospective study, the heart rate variability (HRV) indices were calculated from 24-hour Holter recordings, obtained during normal daily activity, and plasma norepinephrine levels measured, and the data between the patients and the controls compared to quantify the autonomic activity.

The HRV indices were significantly greater in the patient than the controls, and revealed hypervagal and mixed type in 55.2 and 20.7% of patients, respectively. There was the greatest parasympathetic activity in the MVPS patients with presyncope or syncope. The MVPS patients with palpitation tended to show hypersympathetic activity, as in the mixed type.

Our data suggests that MVPS patients exhibit autonomic dysfunction, mostly resulting from parasympathetic hyperresponsiveness.