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Was looking for evidence that orthostatic tachycardia is pathologic, I found this interesting but tiny experimental study that seems to be arguing the opposite: that tachycardia is important for orthostatic tolerance (not intolerance). Effects of cholinergic and beta-adrenergic blockade on...

Currently looking further into Long Covid studies. IJERPH | Free Full-Text | Detecting Orthostatic Intolerance in Long COVID in a Clinic Setting (mdpi.com)

Another interesting one: Orthostatic Intolerance in Adults Reporting Long COVID Symptoms Was Not Associated With Postural Orthostatic Tachycardia Syndrome - PubMed (nih.gov) Peak heart rate during the standing test did not predict OI and the majority of Long Covid patients with tachycardia did...

Sad news: PC-POTS Update Results from the Phase 2 ALPHA study of efgartigimod in post-COVID-19-mediated postural orthostatic tachycardia syndrome (PC-POTS) show that treated patients had no clinically meaningful improvement compared to placebo on the total Malmö POTS symptom (MaPS) score and...

Thanks!

Yes that is probably an issue and your own measurements show that very clearly: there seems to be a large inter-individual variability: one day you have increases with 45, other times only 11 bpm. Some argued that orthostatic tachycardia measurements during standing or tilt testing are a bit...

@Nightsong Do you know of any studies that measured the prevalence of POTS among OI patients? For example: clinics that report the % of POTS in the patients with OI that get referred to them. I found this one paper that says that only 19% of their OI patients fulfilled POTS criteria. Patients...

I think the conclusion is more that POT may not be relevant to the symptoms POTS patients experience. Orthostatic tachycardia seems to have a very weak relationship with orthostatic symptoms.

No did not work but thanks anyway. SNT Gatchaman kindly helped me out.

Yes unfortunately, they do not report how many students had more than 40 bpm HR changes as that would give an indication of the current threshold. They only report the median (20) range (-15 + 61) and 2.5% (-1) and 97.5% (48) quartiles and mention that 23% had a HR increase of more than 30 bpms...

Thanks, it all seems to point to the same researcher: Phillip A. Low at the Mayo Clinic. Phillip A. Low, M.D. - Doctors and Medical Staff - Mayo Clinic

Same finding here: 9 of the 15 controls (60%) had an HR increase that was higher than 30 bpm after 10 minute passive tilt table testing. With a 10 minute standing test, 5 (33%) met the POT criterium. They proposed to increase the HR cutoff to 37 bpm which resulted in a sensitivity of 40% and a...

I suspect that study forms the justification for the > 40 bpm threshold for children, even though it showed that 5% of healthy controls had a HR increase higher than 42 bpm. The study not included healthy controls but also more than 600 children who were referred with diagnoses of orthostatic...

This abstract from a German study did 10 repeated tests and found that it did not lead to stable results. Intra- and interindividual reproducibility of heart rate variations in the tilt-table test - PubMed (nih.gov)

Thanks to @SNT Gatchaman for helping me out. In the study they had a control group of 20 men and 21 women aged 20 to 50 years. For the control group they report that "between the second and third minute of tilt, HR increased by 20.1 ± 8.9 bpm in men versus 14.8 ± 8.1 bpm in women." So it seems...

Thanks but I actually meant the 1993 Schondorf-Low paper where POTS was first defined: Idiopathic postural orthostatic tachycardia syndrome An attenuated form of acute pandysautonomia? Ronald Schondorf, PhD, MD, and Phillip A. Low, MDAUTHORS INFO & AFFILIATIONS January 1993 issue 43 (1_part_1)...

Thanks for the useful references @Nightsong Found some other ones too: Orthostatic heart rate does not predict symptomatic burden in pediatric patients with chronic orthostatic intolerance - PubMed (nih.gov) Orthostatic intolerance without postural tachycardia: how much dysautonomia? -...

Thanks. Does anyone have access to this paper? Haven't been able to find it online.

Where does the idea that >30bpm increase during tilt testing is pathologic came from? Does anyone know how this threshold was justified or where it was first used?