LONG QT

[Jsnichols]

Hello all,

I have a questions regarding QT.  I will start out by saying I have General Anxiety, hypochondria and Panic Disorder.   I recently had 2 ER visits.  The first one started due to a palipitation and then I felt chest discomfort on the left side of my chest. From there I got extremely anxious and couldnt tell if it was panic or my heart. My heart rate was probably somewhere around 180 bpm.  

Went into the ER they gave me an ekg and did some blood work.  When the EKG was obtained my pulse was 119 and they found the following.Ventricular Rate: 119 BPM

Atrial Rate: 119 BPM
P-R Interval: 144 ms
QRS Duration: 106 ms
Q-T Interval: 366 ms
QTC Calculation(Bezet): 514 ms
Calculated P Axis: 79 degrees
Calculated R Axis: 30 degrees
Calculated T Axis: 58 degrees

**Potassium was low at under 3.0

Doctors put me on potassium supplements and my potassium normalized. I had another "attack" where I was hyperventalating and heart rate at about 180 again or higher. Had another EKG and my QTC was under 450 at a heart rate of 100.  

Does this sound like I have Long QT syndrome or was this an acute situation caused by low potassium?

I have had my Primary care physcian consult a cardiologist and preformed a holter and echo-both normal and they are not concerned about Long QT. My ER doctor was not concerned about Long QT as his assumption was that it was cause by low potassium.

I had even sent my EKGs to a arrythmia specialist at Mayo Clinic in Rochester to see if they thought I needed an appointment and they did not feel I needed an appointment given I have no family history of fainting or sudden death.

Am I over thinking this, or should I ask for more tests?
I have also heard this EKGS can give inaccurate results at high heart rates, is this true?

Thank you Josh

[is_something_wrong]

Everyone have their unique relationship between heart rate and QT interval. People with SQTS (Short QT syndrome) have a fixed QT interval, say, 260 msec regardless of heart rate. If such a person had a heart rate of 200, the formula would show a long QT interval. Which clearly is wrong.

My QT interval is somewhat less rate-dependent than what is normal. It really doesn't matter. The QTc correction formulas will just say something about what the formula would think your QT interval if your heart rate was 60 and it is often wrong. It is not dangerous to have a prolonged QTc interval if your uncorrected QT is normal when your hear rate is slow. Likewise, if you had a heart rate of 20 and a QTc of 400 msec, it would be very dangerous because the "true" QT would be really long.

Which is why overdoses of QT-prolonging medications that are causing tachycardia (i.e quetiapine) are far less dangerous than those causing bradycardia (i.e sotalol). When considering risk of Torsades, it's the uncorrected QT interval that matters.

You can read about this on the Life In The Fastlane blog. It has a lot of useful information about QT

[is_something_wrong]

Everyone have their unique relationship between heart rate and QT interval. People with SQTS (Short QT syndrome) have a fixed QT interval, say, 260 msec regardless of heart rate. If such a person had a heart rate of 200, the formula would show a long QT interval. Which clearly is wrong.

My QT interval is somewhat less rate-dependent than what is normal. It really doesn't matter. The QTc correction formulas will just say something about what the formula would think your QT interval if your heart rate was 60 and it is often wrong. It is not dangerous to have a prolonged QTc interval if your uncorrected QT is normal when your hear rate is slow. Likewise, if you had a heart rate of 20 and a QTc of 400 msec, it would be very dangerous because the "true" QT would be really long.

Which is why overdoses of QT-prolonging medications that are causing tachycardia (i.e quetiapine) are far less dangerous than those causing bradycardia (i.e sotalol). When considering risk of Torsades, it's the uncorrected QT interval that matters.

You can read about this on the Life In The Fastlane blog. It has a lot of useful information about QT

[Jsnichols]

Thank you that is very re-assuring.

I have went back and calculated all my qt from the Bezet to the Fredericia

QTc(f)

95 BPM
358 QT
417 QTC

77 BPM
384 QT
417 QTC

152 BPM (Panic attack)
350 QT
477 QTC

77 BPM
398 QT
432 QTC

105 BPM
364 QT
438 QTC

129 BPM (Panic Attack)
322 QT
415 QTC

119 BPM (Panick Attack)
366 QT
459 QTC

80 BPM
376 QT
413 QTC

122 BPM (Panic Attack)
338 QT
428 QTC

What is so discouraging is that Bezet calculated nearly all of these at prolonged however the majority of these were calculated not to be prolonged by fredericia. I know you said Fredericia is the preferable formula but to a person with Anxiety it is tough to look past the Bezet Calc.  I have had a normal Echo, holter, and I am on a MCOT.  

What are your thoughts about these QTC's from my EKGs?  Would this draw concern? My doctors don't seem to be concerned but everyone on the internet feels these QTC when calculated with Bezet is cause for concern.

[is_something_wrong]

When you fear LQTS, you will of course fear Torsades. It is what makes LQTS possibly dangerous.

I can guarantee, by 100% certainty, that this was not Torsades. Torsades is usually pulseless, and manifest with fainting spells. It's the closest you can get to ventricular fibrillation.

It's very rare unless the UNcorrected QT interval is close to 600msec.

[Jsnichols]

I got ya. I have another concern. what are some symptoms of Torsade de pointes. I keep thinking that I had that went I went in. My heart rate was rythmic-just very high, and my body was anxious and tingling from hyperventilation.

How would one know if they have torsade de pointe?

[is_something_wrong]

I think the ECG interpretation software is either programmed to use the Bazett formula or the Fredericia formula. At my GP's office they use Fredericia, but I've seen Bazett been used a lot too. Once I panicked when they connected the electrodes, had a heart rate of 130 and a weird QTc interval (fairly long). And as you can see from the ECG on my profile page, my QT is not prolonged at all, rather on the short side.

[Jsnichols]

It always seems like I have a high heart rate too when they perform the ekg as I am always a little anxious. I have a follow up ekg this next week and a potassium re-check. I am assuming that will tell me a lot. Hopefully I can get my heart rate closer to 60 bpm to give me more of a accurate reading.

Why do clinics continue to use the bazett formula for higher heart rates?

[Jsnichols]

I was just given the potassium supplements and it seemed to normalize. I know they said diuretics could cause longer qt. My diet was pretty bad. I would drink 10oz of coffee per day and wouldnt eat anything until after work.

So my day would be

8AM-5PM
-Coffee/water(4 10 oz off strong coffee)

7PM
-Supper

Could that through off my qt?

[is_something_wrong]

The faster your heart rate is, the more the QTc Bazett formula will overestimate your corrected QT interval. However, your potassium is low and that may contribute to a longer QT interval.

I hope your doctor gave you instructions on how to normalize your potassium levels.

[SlowHeart92]

The worst thing you can do is read up about rare heart conditions if you have anxiety (I've done it). It seems like you've been thoroughly checked out and given the all clear regarding Long QT. If it'd put your mind at ease you could request another holter or EKG at a normal heart rate to be sure but you've had 2 specialists look at your heart rhythm and aren't concerned about it, so I don't think you should be.