Can Inappropriate Sinus Tachycardia (IST) cause Presyncope/Syncope?
by ConcernedFainter, Oct 06, 2012
I finally had three Presyncopes with the 30 day event monitor..one in the afternoon today, and one each yesterday and day before in the evening. They all happened within an hr of eating the same type of food. I felt very sick and had bad palpitations just before the presyncopes...HR was mostly 140's-160's ( one time it was even higher like 170-s-190s, according to my HR app). I was able to capture the episodes today and yesterday but couldn't record the actual episode day before as the monitor was already full during it ( Though I made many recordings just before it).
When I called Cardionet to transfer them, the techs said that it was not urgent enough to call the doctor and that the doctor will see the recordings within 24 hrs..so I'm guessing I had Sinus tachycardia during these episodes and not an arrhythmia ? Couldn't take BP  for 10-15 min afterwards as the BP must have gone low enough to cause the presyncopes.
I have been reading about IST ( My EP said that I have Inappopriate Sinus Tachycardia) and have found conflicting information about it. Can IST cause Presyncope/Syncope? Is this Neurocardiogenic Syncope (NCS)? Thank you!
Member Comments (14)
by spade22, Oct 08, 2012
Yes, IST can cause presyncope and syncope.

by ConcernedFainter, Oct 08, 2012
Thank you for your reply :) I did read that article and some others which say that IST can cause presyncopes and Syncope. When I last talked to my EP about a week ago, he told me that I have IST. He also said that IST doesnot cause Syncope and that there is something else causing all this. That is why I'm confused!??? (I have had many episodes of presyncope and Syncope over the years).
by spade22, Oct 08, 2012
Well there is definitely evidence that IST "can" cause pre syncope or syncope but it may not be common.  I don't think your EP can rule in/out that the IST is/isn't causing your syncope episodes until they are caught on a monitor, so the dr can see what your heart is doing at that time, and it sounds like you have managed to do that.  Can you call the doctors office  today to confirm you caught a syncope episode on the monitor and check whether they received that information? At that time you could also inquire about the arrhythmia captured and whether you need to continue wearing the monitor.    I hope you get some answers soon.
by ConcernedFainter, Oct 08, 2012
Thank you! I called my EP to see if they have received the information. Haven't heard back still. The 3 episodes I had were mild presyncopes and not the really bad Presyncopes/Syncope I get sometimes.....really hope something was captured when I pressed the record button during these.
by spade22, Oct 09, 2012
Did you ever hear back from the doctor?
by madamebrianne, Oct 09, 2012

Please look into Postural Orthostatic Tachycardia Syndrome (POTS). It is a very unheard of nervous system disorder that prevents the body from being able to properly adjust to the pull of gravity. This can cause: rapid heart rate upon standing, high or low blood pressure, fainting, dizziness, palpitations, fatigue, digestion problems, etc. The symptoms are endless and vary from person to person and day to day. I was diagnosed last year after having gone six years trying to figure out what was wrong with me.

For more information, I recommend visiting:

Also, feel free to message me with any questions.

Thanks, and best regards,

by ConcernedFainter, Oct 11, 2012
I finally got a call from my EP's office today. The assistant said that he wants me continue taking Bystolic. When I asked her if the EP saw anything on the monitor results as to what happened during the presyncopes, she said the EP didn't say anything about it and that I should continue taking Bystolic? She also didn't say whether I should continue wearing the monitor or not. So, I guess I'm going to continue wearing it for 3 more weeks?
I just don't know what to make of it and still have no answers as to what happened during the presyncopes :(
by spade22, Oct 11, 2012
How frustrating!

Can you call back and ask more specific questions?  Eg. tell the assistant/nurse "I would like some guidance on whether I  have to continue wearing the Holter monitor since I recently captured 2 syncope events".  This would be a question that only your doctor can answer so when you get an answer you will know he has reviewed the arrhythmia(s).  When the nurse calls you back with the answer, you can follow-up with questions such as "can my appointment be moved forward to discuss the results of the monitor"   "if" there is enough information to make a diagnosis (those 30 day monitors are a pain)

by Mom2four85, Oct 22, 2012
Have you seen a doctor who specializes in ANS issues? I've found so many doctors do not understand Dysautonomia even though it's a pretty common reason for different problems and often goes misdiagnosed.

I believe last year there were something like 500,000 cases in the US alone according to the NDRF (National Dysautonmia Research Foundation) but Orthostatic Intolerance disorders are the least understood of the bunch.  http://ndrf.org/orthostat.htm

Orthostatic Intolerance disorders (http://www.ninds.nih.gov/disorders/postural_tachycardia_syndrome/postural_tachycardia_syndrome.htm) can include Postural Tachycardia Syndrome (POTS); Mitral Valve Prolapse  and Idiopathic Hypovolemia
and there are quite a few other ANS disorders under the Dysautonomia umbrella  

3. What are some examples of specific dysautonomias? •Inappropriate Sinus Tachycardia with Dysautonnomia (IST)

In that thread, there are doctors who understand and treat ANS patients and can help coordinate care with your local doctor.