A prospective study of excessive postural heart rate change on head-up tilt

Healthy subjects with asymptomatic postural tachycardia (≥30 bpm) at baseline were evaluated over a 1-year period to determine whether they developed orthostatic symptoms. Subjects were evaluated at baseline and at 1 year using the autonomic reflex screen and autonomic symptom profile (ASP). Heart rate increment on HUT did not differ at baseline (40.6 ± 7.5 bpm) or at 1 year (37.1 ± 11.1 bpm; n = 26; p > 0.05). Orthostatic symptoms measured by the ASP did not reveal significant orthostatic dysfunction throughout follow-up (baseline, 7.88 ± 7.61; 1 year, 9.04 ± 6.64; n = 26; p > 0.05). The ten autonomic domains of the ASP did not reveal a change in autonomic symptoms from baseline (13.56 ± 13.66) to 1-year follow-up (15.12 ± 11.62; n = 26; p > 0.05). Cardiovagal function was unchanged between baseline and follow-up for both heart rate variability to deep breathing (baseline, 23.9 ± 11.6 bpm; 1 year, 23.0 ± 9.3 bpm; n = 26; p > 0.05) and Valsalva ratio (baseline, 2.16 ± 0.39; 1 year, 2.15 ± 0.33; n = 26; p > 0.05). These findings further argue that heart rate criteria (≥30 bpm) for Postural Tachycardia Syndrome (POTS) are not appropriate in younger individuals and higher postural heart rates do not predispose individuals to the development of POTS.