Inappropriate sinus tachycardia in long-COVID and other updates on recent autonomic research, 2022, Miglis et al

Inappropriate sinus tachycardia in long-COVID

As the COVID-19 pandemic continues to affect hundreds of millions of people worldwide, autonomic complications are being recognized with increasing frequency in both the acute and chronic form of the illness, the latter now designated as post-acute sequelae of SARS-CoV-2 (PASC), colloquially termed long-COVID. Tachycardia is a common symptom of PASC, and some patients may be diagnosed with postural tachycardia syndrome (POTS) or inappropriate sinus tachycardia (IST). While post-COVID POTS has garnered more attention from the scientific and popular press, IST may be equally or more common and has been reported in survivors of the prior SARS coronavirus pandemic [1]. The etiology of IST is unknown; however, the proposed mechanisms overlap with those of POTS, including increased sympathetic and/or reduced cardiovagal activity.

Open access, https://link.springer.com/article/10.1007/s10286-022-00854-5

 

I suffer from intermittent "inappropriate sinus tachycardia" although I've never heard it called that, and it was put down to anxiety (naturally - doctors are very consistent in some scenarios). In my case it turned out to be caused by severe iron deficiency which I had to deal with myself. Once it was triggered it never went away completely and I still have to take beta blockers occasionally.

I would be interested in knowing if IST could arise from other types of nutrient deficiency other than iron, but I can't afford to test every possible mineral and vitamin or other nutrient, and I know damn well that my GP surgery would refuse to do it.

 

I tried to google but got some confusing results.

Do you know whether "inappropriate sinus tachycardia" is the same as supraventricular tachycardia (SVT)? Or maybe it's a superset? Subset?

EDITED: Oops! I just read the study and found the IST definition:

"IST was defined according to consensus criteria as symptomatic sinus rhythm rate ≥ 100 bpm at rest with a mean 24-h heart rate above 90 beats/min in the absence of any acute physiological demand or conditions known to produce sinus tachycardia."​

Deleted the rest of my comments.

 

I have always assumed they are different, but then I am not reliable on this subject and anything I say should be checked.

My understanding of sinus tachycardia, that I was told by some doctor, but can't remember who or in what context :

If a healthy and fit person with a normal heart rate at rest of 60 bpm was to go out and exercise and raise their heart rate to 140 bpm, that is sinus tachycardia. But in that case, after they stopped exercising their heart rate would reduce to their normal level (60 bpm). That is "appropriate sinus tachycardia" and is not a health problem.

But someone who gets out of bed and their heart rate rises to 170 bpm almost immediately for no obvious reason may have inappropriate sinus tachycardia or some other form of tachycardia, of which there are several kinds.

https://en.wikipedia.org/wiki/Tachycardia#Differential_diagnosis

And looking at that link suggests what I was told about inappropriate/appropriate sinus tachycardia was probably wrong. *Sigh*

 

Edited: I meant to start out by saying I'm sorry your doctor gave you incorrect or confusing information about IST!

After I posted (oops!) I saw the IST (inappropriate sinus tachycardia) definition in the study. So I edited my post.

Using the study definition IST is different from SVT.

This paper, which discusses IST in Section 2, has a lot more detail:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5267948/