Clinical characteristics of postural tachycardia syndrome with and without hypermobile Ehlers-Danlos syndrome: a pilot study

Background The clinical characteristics of postural tachycardia syndrome patients with and without hypermobile Ehlers-Danlos syndrome remain unclear, particularly in the Japanese population. This study aimed to clarify the clinical features and laboratory findings of patients with postural tachycardia syndrome and hypermobile Ehlers-Danlos syndrome. Methods We retrospectively analyzed patients who presented with orthostatic intolerance at our hospital between April 2023 and July 2025. Of these, 21 patients were diagnosed with postural tachycardia syndrome using the head-up tilt test. The clinical features and test results of these patients were compared to those of patients with and without hypermobile Ehlers-Danlos syndrome. Results Of the 21 patients diagnosed with postural tachycardia syndrome, 4 were also found to have hypermobile Ehlers-Danlos syndrome. A significantly higher frequency of menstrual disorders was observed in the hypermobile Ehlers-Danlos syndrome group than in the non-hypermobile Ehlers-Danlos syndrome group (100% [4/4] vs. 23.1% [3/13], p = 0.015). Other clinical features and laboratory findings were similar between the groups. Conclusion These observations provide a rationale to hypothesize a possible contribution of connective tissue-related factors to disease progression. Larger studies are warranted to investigate whether a meaningful association exists between postural tachycardia syndrome and hypermobile Ehlers-Danlos syndrome.