Higher postural heart rate increments on head-up tilt correlate with younger age but not orthostatic symptoms.

Reports have shown that younger individuals present with higher postural heart rate increments on head-up tilt (HUT). However, a correlation between the degree of heart rate increment and symptoms of orthostatic intolerance has not been determined. The objective of this study was to determine whether higher postural heart rate increments during HUT correlate with symptoms of orthostatic intolerance in healthy subjects. Postural heart rate increment on HUT did not differ between men and women (P = 0.48) but did show a significant decrease by age group (P < 0.0001). There was a significant negative correlation between heart rate increment on HUT and age [r = -0.63 (-0.73, -0.51), r(2) = 0.400; P < 0.0001]. There was a significant difference with respect to symptoms of orthostatic intolerance by sex (P = 0.03) but not age (P = 0.58). There was no significant correlation between either symptoms of orthostatic intolerance and age [r = -0.13 (-0.31, 0.06), r(2) = 0.017; P = 0.17] or heart rate increment on HUT and symptoms of orthostatic intolerance [r = 0.15 (-0.04, 0.33), r(2) = 0.022; P = 0.13]. The results demonstrate that higher postural heart rate increments in younger individuals do not result in an increase in orthostatic intolerance. This highlights the potential need for a reevaluation of the diagnostic criteria for postural orthostatic tachycardia syndrome in younger individuals.