QTc Numbers

[bbxx]

So I am looking over my records and it says on one of my old reports my qtc was 394.
I thought qtc was suppose to be below 400. Isnt 394 pushing it?

[jaysonrl]

Four and a half years later this post is still helpful.  Thank you all!  I was worried about my QTc, but then I did some of the other calculation and found it was not high.  Just the Bazett put the QTc borderline high.  HR - 99, QT 372 / QTc - 477 (more like 430 w/ QTc-f).  And nowhere near 500.  Good to go.

Thanks!

[Mom2four85]

ahhhh haven't seen that in ages :(  only read a couple posts at the top and skimmed over it

[is_something_wrong]

That stupid CPVT post again :p

[Mom2four85]

what?

[bbxx]

HUH?

[is_something_wrong]

Oh.. someone pulled up that terrible post again.. see community front page. see you in a couple of days:p

[bbxx]

No, all my tests say qtc normal

[Mom2four85]

oh wow sorry I should know what it is...beeen a very long week and even longer day.  no need to answer :(

bbxx did you ask your dr about this? I go for a new ekg and echo next thurs and will ask again

[Mom2four85]

what's atrial pacing?

[bbxx]

ha ha "thats easy to explain"
I would love to have your brain for a while  :)

[is_something_wrong]

Thats easy to explain. you were on atrial pacing at rate 60. Then qt and qtc are similar.

[Mom2four85]

ekgs are bewildering to me....when my QT/QTC was 398/473 my HR was 85 - the dr said something about prolonged QT and asked if anyone in my family had LQTS?  I've also had QT/QTC intervals that were the exact same numbers which had doctors scratching their heads saying that's not possible.

too bad I don't have any ekg's where my HR has been high they might be interesting to see - I saw on my latest ICD interrogation I've had some NSVT runs where my HR was 350 - 425 which scared the heck out of me...luckily only 1-3 sec ranges.

[is_something_wrong]

We all have an unique profile on how the QT is narrowing with increasing heart rate. My QTc is a bit prolonged on high heart rates, possibly because my QRS is a bit wide (approx 105 msec) and this is included in the QT time.

At rest, rate 60, my QT is about 380 msec. At rate 80, it's about 340 (QTc 390), and at rate 100 it's 320 (QTc 413). Of course, this varies a lot with stress levels, etc.

It seems QT times are a bit dramatized at this community. LQTS is extremely uncommon, and it seems most people measuring prolonged QTc are "victims" of the famous Bazett over-correction with high heart rates.

[jkfrench]

I was wondering the same thing.  My qt was 372 but my qtc was 462.  Then they did a repeat ekg and my qt was 374 and qtc was 477.  The ekg printout never stated long qt or possible long qt.
My heart rate was high as I was nervous (98).  I have now asked 3 doctors about this and have been told the same things as you stated.  They are not worried if it isn't over 500, plus they also told me that it would have been evident during my stress/echo last month or on any of my stress tests and ekgs over the last 20 years.  They rely on those tests rather than just the ekg.   I have to belive them.   Jodie

[is_something_wrong]

Are you sure it's QTc and not QT?

The QTc is just a formula and the physicians still debate which of them should be used. At high heart rates, Bazett's formula will really often give high results results (close to 500 msec (at stress tests, etc.). When my mom had a stress test done, I asked her cardiologist about this specificly.

At heart rate 180 her QTc (Bazett) was close to 500 msec, the QT was 280 msec. If the Frederica formula is used (which it often is) the QTcF would be 404 msec.

[stevie_wonder]

A QTc (correced for heart rate) over 500ms is dangerous and can lead to Torsades. A QTc over 470ms for a woman and 460ms for a man is considered prolonged and needs to be checked out for causes, whether it is from medications, medical conditions or Long QT Syndrome, a prolonged QTc can result in Torsades.

[bbxx]

Well, I am terrible at math, so I cant try to figure it out. lol
I do see my records show it changes though.

[is_something_wrong]

Well, your QT varies all the time. Take a look at the EKG on my profile, there you can see my QTc is 358 ms. That's a bit short, but in that case, my adrenaline levels were high despite my low heart rate. That decreases QT.

If you measure your QTc during times with high heart rate without physical activity or anxiety, your QTc may prolong.

What's important is that your REAL QT time, not corrected after the QTc formula, isn't above 500msec, because then (and only then) your risk of TdP increases. 95% of us have QT time at heart rate 60 of 360-440 msec (460 for women). That doesn't mean that 2,5% of us have LQTS (2,5% is above 440 and 2,5% is below 360).

The QTc formula is a mathematical formula that fails at higher heart rates. The phenomenon "LQTS" can the doctor see as specific changes in the T wave, it's usually not just prolonged, he can see changes consistent with potassium channel diseases, like a notched T wave.

[bbxx]

Wow, thats great that you are able to relax and move on! I thought I was doing great when I was having bigeminy then tri for quite the while the other day. I was so calm about it too. Then the pre-syncpe thing.... back to sqare one.
:)

[jkfrench]

Funny you should mention the QT/QTc numbers.  I have had stress tests, ekgs, echos for the last 20 years and noone every mentioned to me that my QTc number was high.
So last month, I was getting these fleeting pains in my upper stomach up to my chest.  I really didn't think it was my heart but I called my cardiologist who was of course on vacation.  Then I called my internist who was also on vacation.  Ugh,  so the office told me to go to urgent care just to make sure it wasn't my heart.  Off I went.  They ran an EKG.  My heartrate was high (98) as I was nervous.  I wasn't having a heart attack (which I knew), but the ekg for the first time stated possible left atrial enlargement; ST abnormality, possible digitalis effect.
So, I was at Scripps and because my cardiologist didn't work out of that hospital, they had nothing to compare my ekg to.  I was told there were non specific changes (whatever that meant) and released to talk to my doctor the next day.  The office called and said that everything was fine as they compared it to my existing ekg's etc.  I then told them I saw that my QT/QTc was 372/462 on the printout.  This of course scared me.  I was told that these printouts are not always accurate and that I did not have long QT.  They ordered a stress/echo to be on the safe side because of the stomach/chest pain and that was completely normal except for 5 isolated pvcs during the time they put me back on the table for the echo after I ran 16 minutes up to level 6.
So I agree with you that it isn't very reassuring when these machines can compute mistakes.
I have never fainted in my almost 50 years and I would imagine if I really had long QT that it would have shown up on this last stress/echo test.
I see a new cardiologist tomorrow.  I will make sure and ask him about this again.
I have decided that I am not worrying about this anymore.  I'm done trying to figure it all out.  I have to trust these doctors at some point.  I decided this about a month ago, and my heart has settled down and I actually have some days that I don't feel any skips at all.  
So try not to stress too much until you get all your info back.
Jodie

[bbxx]

If only I hadnt fainted again. Then I would not even be doing this. UGH!
Thank you for the info... :)

[is_something_wrong]

Both 396 and 422 is perfect. probably depending on your heart rate. try to forget such details on your ekg (easier said than done;)

[bootielious]

Mines is 374 447 is that good are bad

[bootielious]

Mines is 374 447 is that good are bad

[bbxx]

Thanks. I will those up for sure.

[Mom2four85]

I forgot...the skipping hearts website was where I found the EKG parameters with references...on the front page theres a link for normal cardiac values and part way down it has the EKG info