Drug-induced long QT?

[momof419]

I just stumbled upon some readings about drug-induced long QT and have some concerns.  About 7 years ago I suddenly became intolerant of many antibiotics.  Recurrent UTI's led me to this realization as the many antibiotics weren't getting rid of them, but instead were leading to rash, rectal bleeding, etc.  I then began Macrobid daily and right around 6 months of use started experiencing faintness and dizziness, tingling in the extremeties, shortness of breath, racing heart and rust-colored urine.  I wasn't really surprised because I have a family history of intolerance to antibiotics.  However, I had taken many up until that point, including a number as a teenager when a full round of Accutane failed to clear up my complexion.  I honestly don't even know what all antibiotics I have taken.

In any case, not long after the onset of all these symptoms, I was diagnosed with hypo-thyroid.  That was odd because I had always had a very fast metabolism and was only 24 with no other health issues.  A couple of years later, I was still experiencing faintness, dizziness, and spells of racing heart.  I was diagnosed with a number of things from seasonal allergies to arrhythmia.  One GP said that he could hear a distinct arrhythmia, did an EKG and said it was there; but when he referred me to a cardioligist, I was told they didn't see anything notable and it wasn't life-threatening anyway.

I am still bothered by racing spells brought on by excitement and exercise, and I'm exhausted all the time.  Also, during my last pregnancy I gained very little weight and found after the baby was born I actually weighed 10 lbs. less than my pre-pregnancy weight, and in over a year have been unable to put it back on.  And I hate when I lay down at night and suddenly feel my heart race and my breathing get short.

Could it be related to drug-induced long QT?  Thank you for your time.

[dani126604]

I am going into my 8th month of pregnancy. I was recently in the ER due to some chest pain, during the visit the er doc told me that everything looked fine (I was concerned about an embolism) but he did find a prolonged qt. It was about 450 at the time. ABout a week later I saw an Cardiologist and he ordered a stress echo. During that test my qt was at 490 and did not shorten with exercise, but everything else with my heart seems fine. So, he is at a loss, he is not sure whether I truly have long qt or not. He has suggested that I wait until I have my baby to go see an electrophycist.

I have done some research on my own, because this is quite shocking to me, as I have never had a symptom and no family history. I see that being hypo-thyroid may have some affect on the qt. That same day as my stress echo I had my thyroid tested. I had graves disease at age 17 and have been monitored for the last several years. The test came back that I was being significantly under-treated and I have now moved up to 200mcg once a day. So I guess my question is, do you think I have acquired long qt because of my thryroid issues. And if so, do you think it will be a non-issue so long as my thyroid is properly monitored?

Thanks for your help with this.
D

[Michael J. McWilliams, M.D.]

Drug induced long QT syndrome is only there when you are taking the offending drug.

There is a long list of medications that prolong QT interval in susceptible patients.  The Heart Rhythm Society websites has information page and the list of medications.

http://www.hrspatients.org/patients/heart_disorders/long_qt_syndrome.asp

Most people with long QT syndrome don't even know that they have it -- essentially no symptoms.  Most of the symptoms you describe are not typically associated with long QT.  If isn't seen on your EKG and you don't have a family history of it, you probably do not need to worry about this one.

I hope this helps.  Thanks for posting.