Primary autonomic failure (PAF) is a progressive impairment of the autonomic nerve fibers concerning the two major components, sympathetic and parasympathetic. It is characterized by a combination of supine arterial hypertension (HT) and orthostatic hypotension (OH) without elevation of heart rate (HR).

To establish the autonomic profile of patients with PAF.

Study design: a prospective study conducted in cardiology A department of Ibn Sina University Hospital Center, in collaboration with exercise physiology and autonomic nervous system team, from June 2022 to June 2023.

Inclusion criteria: patients with functional signs of PAF, with absence of neurological signs.

Exclusion criteria: patients with severe HT, secondary or complicated HT.

The cardiovascular autonomic testing included Deep Breathing (DB), Hand-Grip (HG), Mental Stress (MS) and orthostatic tests were performed.

A total of 30 patients were included. The average age was of 53.2±6.4 years and 67% were females.

The results of cardiovascular autonomic tests were as follow: vagal response obtained during DB test was of 19.0%±4.8; vagal response and alpha peripheral sympathetic response obtained on HG test were of 7.3%±1.7 and 8.6%±1.4, respectively; alpha central sympathetic response and beta central sympathetic response obtained during MS test were of 7.9%±1.3 and 8.9%±1.1, respectively. Vagal response, alpha peripheral adrenergic sympathetic response and beta peripheral adrenergic sympathetic response obtained during the orthostatic test were of 7.2%±1.6, 6.1%±1.7and 7.4%±1.5, respectively.

Our study showed a significant vagal and sympathetic impairment, with severe orthostatic hypotension without elevation of heart rate, which could be responsible for syncope in the absence of neurological signs in patients with primary autonomic failure.