Hemodynamic profile and heart rate variability in hyperadrenergic versus non-hyperadrenergic postural orthostatic tachycardia syndrome

Abstract Objectives To investigate differences in hemodynamic profile between hyperadrenergic and non-hyperadrenergic postural orthostatic tachycardia syndrome (POTS) in response to head-up tilt test (HUTT). Methods Ten patients with hyperadrenergic and 33 patients with non-hyperadrenergic POTS underwent HUTT consisting of a 10-min supine phase and 30-min 70° tilted phase. Heart rate (HR), systolic and diastolic blood pressure (dBP), and heart rate variability (HRV) parameters of the two groups were compared. Results Hyperadrenergic patients had higher supine HR (82.6 ± 16.3 bpm vs. 73.8 ± 10.4 bpm, p  = 0.048). Supine HRV analysis showed significantly lower cardiac vagal activity and possible predominance of cardiac sympathetic activity in the hyperadrenergic group. Non-hyperadrenergic patients had lower dBP during the first four minutes of tilt. Furthermore, 60% of non-hyperadrenergic patients had lower average dBP in the 1st minute of tilted phase when compared to supine values, whereas only 2 of 10 hyperadrenergic patients exhibited the same response. Syncope or intolerable symptoms, causing early ending of HUTT, developed earlier in the non-hyperadrenergic group (8.9 ± 6.8 min vs. 21.2 ± 3.5 min, p  = 0.001). Conclusion Hyperadrenergic and non-hyperadrenergic type of POTS seem to have distinctly different response to HUTT. Significance This study has shown significant differences in hemodynamic response to HUTT between hyperadrenergic and non-hyperadrenergic type of POTS indicating possible differences in their pathophysiology.