Normal versus abnormal: What normative data tells us about the utility of heart rate in postural tachycardia, 2019, Baker and Kimpinski

There were 252 participants in this study of which 123 in the age group of 18-29 (where POTS diagnosis is common).

They only did 5 instead of 10 minute testing but don't think that would impact the conclusion (one would expect the HR increase to be even higher with 10 minute testing).

Half of the 123 healthy young people had an HR increase of 33 or higher. 5% had an increase of 50.9 of higher.

 

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?

 

The original criterion in the 1993 Schondorf-Low paper was 2SD above the mean for a sex-matched control population which excluded children and adolescents. I'm not sure who originally proposed the 30bpm value but in the 2011 consensus statement the definition is characterized by a sustained heart rate increment of 30 beats/minute within 10 min of standing or head-up tilt. . . For individuals aged 12–19 years the required increment is at least 40 beats/minute.

I don't have the energy to check right now but the history is fairly well-documented in the Gall et al. "Postural Tachycardia Syndrome" book.

 

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

 

https://ovidsp-ovid-com.libproxy.ucl.ac.uk/ovidweb.cgi?T=JS&CSC=Y&NEWS=N&PAGE=fulltext&D=ovft&AN=00006114-199301000-00024&PDF=y

this may work @ME/CFS Skeptic but you need to paste it into the search line, otherwise you get something from El País!

 

This paper (link) may also be of interest:

Also, of some potential interest given the use of POTS criteria in paediatric populations - from a paediatric study (link):

And an older study in adolescents:

 

I think that patients who have no previous experience with this test will have raised heart beats simply because it is a new procedure to them and do not fully understand everything that will happen . results would be skewed by this.

 

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? - PubMed (nih.gov)

Higher heart rate increments on head-up tilt in control subjects are not associated with autonomic dysfunction - PubMed (nih.gov)

 

Psst

 

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) 132
https://doi.org/10.1212/WNL.43.1_Part_1.132
https://www.neurology.org/doi/10.12...=ori:rid:crossref.org&rfr_dat=cr_pub 0pubmed

 

Oh LOL. I've DM'ed you.

 

I actually haven't come across a paper that tries to assess pre-test apprehension in head-up tilt, although while searching yesterday I found a Roma et al. paper that briefly considered the potential effects while performing passive-standing tests in POTS patients:

 

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)

 

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 intolerance, lightheadedness, orthostatic tachycardia, and postural tachycardia. Then they compared to two and the difference was minimal. At the 10 minute point the 22 healthy controls even had a higher HR increase than the patients with orthostatic symptoms.




The authors write:

Source: https://www.sciencedirect.com/science/article/abs/pii/S0022347611008845

 

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 specificity of 73%. That means that 60% of the POTS patients would no longer meet that threshold, while 27% of the healthy controls would still do.

Instead of requiring a new threshold those numbers show that orthostatic tachycardia testing cannot reliable discriminate between those with orthostatic symptoms and healthy controls.

 

I've found an earlier reference than the 2011 consensus statement for the use of a 30 bpm threshold: this 1999 follow-up paper by Low et al.

ETA: I'm not sure that that paediatric study could have formed the basis for the 40 bpm recommendation in the consensus statement since it was published on October 13 2011 and the consensus statement was published on March 24 2011.

 

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