Improvement in low upright baroreflex sensitivity is associated with positive clinical effect of orthostatic training.

AIM: To assess the clinical efficacy of orthostatic training (OT) and its effect on the autonomic activity.

METHODS: OT was performed in 38 patients (13 males, age 36.4 ± 15.2 years). Baroreflex sensitivity (BRS), heart rate variability, and quality of life (SF 36) were assessed before and after 6 months of OT. Patients with no recurrence of syncope and reduction of the presyncope number to one-third or less were classified as responders.

RESULTS: Compliance to OT was low. Only 55% (38 from 69 patients) completed the training programme; 28 patients were responders (74%) and 10 patients were nonresponders. Before OT, BRS in upright position was lower in responders than in nonresponders (sitting: 8.05 ± 3.94 ms/mm Hg vs 12.51 ± 5.3 ms/mm Hg, P = 0.04, standing: 5.08 ± 2.34 ms/mm Hg vs 7.54 ± 2.16 ms/mm Hg, P = 0.02). After OT, BRS increased in responders (sitting: 8.05 ± 3.94 ms/mm Hg to 9.31 ± 4.49 ms/mm Hg, P = 0.05; standing: 5.08 ± 2.34 ms/mm Hg to 5.96 ± 2.38 ms/mm Hg, P = 0.03). No differences in supine BRS were observed. In responders, low frequency (LF) and high frequency (HF) power in sitting and standing positions significantly increased after OT (P < 0.05). In nonresponders, there was no significant rise in BRS, LF, and HF after OT. A significant increase in quality of life was noted in responders, but not in nonresponders.

CONCLUSIONS: OT reduced symptoms in 74% patients who trained regularly. However, the compliance to training was low. Possible mechanism of OT is reconditioning effect on baroreceptor reactivity in upright position.