Questions about IST

[sugarpea013]

I am a 24 year old female, 5'6" 128 pounds.I follow a very healthy diet, bmi of 18 and bp's range from 80/55 to 100/70.  Prior to my heart bothering me I was extremely active, working out intensely with cardio and weight training on most days of the week.
I have been experiencing tachycardia for the last 4-5 months. Normal resting rate 50-70 but upon standing elevates to 90-140bpm. During times of high anxiety it will go to 190's. I went to a cardiologist and all the tests showed up fine, but showed sinus tachycardia. Negative for pheo and tumor function normal. EP doc said I had IST and prescribed beta blockers. I have not taken them, as I do not believe in relying on medication and truly feel as though this will just "go away".

Can I still work out? I have been terrifed to work out as my heart rate goes so high just by standing. I do light work outs consisting of abdominal work and floor exercises with light weights. But even then I have to take breaks every 10-15 minutes as I get too dizzy. My heart rate hasn't exceeded 140 during these workouts. I wonder if anxiety has more to do with this?

Is there any documention of IST just going away?
Are there any long term risks of my heart rate being accelerated? Like I said it tends to be normal upon rest, but when I'm up and about it runs higher. But normally no higher than 140. During panic attacks it can go up into the 180's. I have tried ativan and that helped, but I hate being dependant on meds.

Thank you for all your advice, comments and suggestions.

[Michael J. McWilliams, M.D.]

start with a low dose beta blockers if you are sensitive

we stop beta blockers on people with heart disease (coronary artery disease) and very rarely have an adverse event.  You have a normal heart and should have no problem coming of beta blockers.

[sugarpea013]

Would you mind terribly answering one more question. I can't tell you how truly appreciative I am of your service. The health care I receive is through the Disabled Veterans Affairs and it literally takes months and months to be seen. And even then I believe the standards of care are poor.

My question is in regards to the beta blockers. You say that my risks of being on a bb are less than not being on one.

What about the times when my pulse is low. While I am sitting or lying down it is generally low, at times in the 50's. I'm worried about it being too low. I am extremely sensitive to meds. In fact when I was prescribed the ativan I only took .25 and it more than did the job.

My other concerns with the bb are long term effects and coming off of them. Wouldn't it put more strain on my heart? I apologize for all the questions. I'm truly desperate for advice and answers.

[sugarpea013]

Thank you so much, I am very grateful for your response.

Take care

[Michael J. McWilliams, M.D.]

It sounds like you are under a lot  of stress.  We don't really understand the mechanism of IST that well.  Stress probably plays some role but it is unclear how important that role is.  It is interesting that 80-90% of people with IST are woman and work in health care -- we don't know what this is.

Can I still work out?

You can still work out.

I wonder if anxiety has more to do with this?

It might, but there is no way to know for sure unless it completely goes away when your stress abates.

Is there any documention of IST just going away?

I haven't seen any cases that go away.  That is a tricky question though because people don't always seek care right away.  There might be some people that get better before they ever present to a doctor or soon after.

Are there any long term risks of my heart rate being accelerated? Long term effects of elevated heart rate?

I will answer both these questions at once, because it is the same answer.  In longitudinal studies, lower resting heart rates are associated with decreased cardiovascular disease.  It is difficult to estimate what the risk of long term elevated heart rates is.  


Will not taking the beta blockers jeopardize my health?
Long term effects of elevated heart rate?

I would also recommend a beta blocker and I would slowly titrate up the dose.  If you have early symptoms of fatigue, try to stick with the beta blocker or decrease the dose and more gradually increase it.  I think beta blocker is the right initial choice.

I think the risks of being on a beta blocker is less than the risks of not being on one.

I hope this helps answer your questions and that your social stresses decrease soon.
Good luck.

[sugarpea013]

I forgot to mention;

This started acting up when I had my daughter last October. It was a traumatic emergency delivery, and the heart skipping and episodes became more frequent and longer in duration. I am consistantly under a great amount of stress. The Army is trying to pull me back and deploy me, my husband and I are both full time students in the medical field, we moved away from all our family and friends, and we are dealing with financial struggles. I have been prescribed ativan, which helped a lot with my anxiety but I don't want to become dependant on any medication.

Will not taking the beta blockers jeopardize my health? Long term effects of elevated heart rate?