OTc averages

Hello,
    My 13 year old daughter was tagged on a EKG machine as being 'borderline Long QT syndrome'.  A pediatric cardiologist that my regular doctors office uses looked at it, and deemed it 'normal'.  However, to be safe, we decided to be referred to a pediatric cardiologist.  We went today, and again the machine did tag her as boderline long QT, but this specialist also corrected it, and said her numbers were normal.  She explained to us that this happens alot with children her age, something about how the machine calculates it from the second lead, and it is not an accurate calculation, she explained it in detail, but just to explain quickly.  She also had an echocardiogram today, that the doctor told us was completely normal.  We don't have any family history that we really know of, other than my Father did die of sudden death when he was 69, but I think his situation was different, because he was suspected of having an infiltrative heart disease such as amyloid, and was having severe symptoms of heart failure.  He had many tests in his life, and we never knew him to have Long QT.  Anyway, my question is, she mentioned to me today that her corrected OTc was 420, which puts her right in the normal range.  This is difficult to look up, and I am wondering, is 420 an ok number, or is that still a bit high?  I am wondering if this is the type of test that we would like to see a lower number.  Is it considered to be where the lower the better kind of thing, or is 420 right in the right range?  I am just wondering if this is average, or it should really be lower at her age.  I read a couple things that borderline dosen't start until 440, but one other thing I think said something about 420 starting at borderline.  The doctor today seemed to think she was just fine, and gave her the clear to run cross country, and she said she thought that Long QT was something she did not have.  Thank you so much!!

[Michael J. McWilliams, M.D.]

Good questions.

the QT interval is an indirect measure of your hearts repolarization time -- the time it needs to get ready for the next beat.  The concern is that is if the heart repolarizes in a way that leads to some of the heart being ready to beat again other parts not being ready, this can lead to dangerous arrhythmias.

The upper limit of normal for a corrected QT interval is 440 msec.  That is where the curve for increased risk of arrhythmias start to increase from what is considered normal.  420 msecs is normal -- no question about that.

It is also true the EKG machines over read long QT intervals -- they call it too often.
If you have seen two cardiologists and they agree the EKG is normal and there is no family history of sudden unexpected death in a person under the age of 45, drownings, sudden infant death syndrome or passing out, it sounds like she is very low risk and is normal.

please wish her good luck in her cross country season for me ;)

[tickertock]

42 is normal, especially in a female. My QTc corrected usually varies between 40-42 which is still normal and I'm male nearly 43 years old. As far as I can remember 44 borderline for male and 45-46 borderline for female, more important is if there is family history.

[stevie_wonder]

Hi valger59,
The doctor on this forum is correct in saying that your daughter is probably fine as 420 for a 13 year old girl is definitely in the normal range. The diagnostic criteria for Long QT Syndrome uses the QT measurement as only one factor in the diagnosis. Family history, ECG changes involving T waves, arrythmias, symptoms etc. are all used, so I would think it is very safe to say that your daughter is fine. Our family has a very long family history of sudden death along with many other abnormalities that were used in our diagnosis. The normal QTc range for girls over 15 goes as high as 460.

[valger59]

Thank you all so much for the wonderful responses!  I can't tell you how much better this all makes me feel!  I know that Long QT can be a difficult thing to diagnose, and is not an exact science, and so thank you for telling me to the best of your knowledge what you think is the most likely scenario.  I was so nervous when the pediatric cardiologist came in and said that my daughter was also tagged by her machine as long qt, because I figured that two different machines saying that would make the diagnosis much more likely.  But, she did reassure me, and she also told me, which I did not know, that the first specialist that looked at it was also an electrophysisist,(sp?).... and I know that's good to have that type of specialist look at it.  
     She seems to be doing great in cross country, and I am grateful beyond belief that I didn't have to have the heartbreaking task of telling her that she couldn't participate in that.  Her being involved in this sport is changing our family's life, because we are suddenly taking her out to the track in the late afternoons instead of sitting around at home, and my husband and I definitely need to get some exercise!!  
     It is reassuring for those of you out there that might have Long qt in your families that there is good treatment options now.  From the research that I've done on it so far, it seems that the most dangerous thing about Long QT is just not knowing about it.  Once you know about it, the knowledge is power, and there is treatment.  Also, from what I understand the risk of sudden death decreases as you get older.  The most dangerous time seems to be in puberty for some reason.  Although, my pediatric cardiologist seemed to suggest to me that even those that have Long Qt don't have a huge risk of sudden death, that it still is a rarely occuring thing.  But, I hope that all of those out there that might have it in their families get checked, and get treatment, because that is literally the difference between life and death.  It's one of those very treatable things, so lets hope we can at least raise some awareness.  
     Thanks again so much for all of your help, this is the best board!!  I hope I can somehow return the favor sometime, thanks, Val

[valger59]

Hey~~
   One real quick last thing, I just noticed something didn't post right on my last letter----in the 'To:' box, I had put To: the doctor, tickertock, and Stevie Wonder, but it didn't all come out, and I wanted to make sure you all knew how much I appreciated all of your responses individually.  Just making sure!  Thanks so much to all of you~~Val