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What Causes Different QTC Results From Hospital To Hospital?
Question: Hi i had several panic attacks, went to the ER five times and did an ECG. The readings of the ECG regarding the QTC differ from one hospital to the other:
In one hospital I got the following results:
HR 104 / RR 577 / PQ 96 / QRS 68 ms / Qt 346 / QTC 461 Axis P 72 QRS 68 T 34
The cardiologist told me the machine could go wrong and corrected the QTC at 416
the next day i did the ECG at another hospital: 115 bpm/PR 110 ms/ QRS dur 70 ms/ QT 329/ QTC 397 - P-R-T axes: 74 72 48
I am worried that i have long qtc as doctors believe that i need Zoloft but I am afraid to take it. Could hospital machines use different formulas for the QTC calculations? how will i know which is the right one? i did an echo and holitor monitor, cardiologist said normal.
In one hospital I got the following results:
HR 104 / RR 577 / PQ 96 / QRS 68 ms / Qt 346 / QTC 461 Axis P 72 QRS 68 T 34
The cardiologist told me the machine could go wrong and corrected the QTC at 416
the next day i did the ECG at another hospital: 115 bpm/PR 110 ms/ QRS dur 70 ms/ QT 329/ QTC 397 - P-R-T axes: 74 72 48
I am worried that i have long qtc as doctors believe that i need Zoloft but I am afraid to take it. Could hospital machines use different formulas for the QTC calculations? how will i know which is the right one? i did an echo and holitor monitor, cardiologist said normal.
Brief Answer:
All labs normal. No worries, focus on anxiety management
Detailed Answer:
Thank you for asking
I read your question and i understand your concern. The QTC you are worried is still in normal range and slight variation due to many errors including machine error can be the reason behind it.
I want you to know that
QTc is prolonged if > 440ms in men or > 460ms in women
QTc > 500 is associated with increased risk of torsades de pointes
QTc is abnormally short if < 350ms
A useful rule of thumb is that a normal QT is less than half the preceding RR interval
Aslo there are different ways to measure the QTC like bazette's. fradrecia, framingham and hodges etc. All of them are equally valid and may give slight variation. Bezette's is used commonly though.
Bazett’s formula is the most commonly used due to its simplicity. It over-corrects at heart rates > 100 bpm and under-corrects at heart rates < 60 bpm, but provides an adequate correction for heart rates ranging from 60 – 100 bpm.
At heart rates outside of the 60 – 100 bpm range, the Fredericia or Framingham corrections are more accurate and should be used instead.
If an ECG is fortuitously captured while the patient’s heart rate is 60 bpm, the absolute QT interval should be used instead!
Nut shell, all your readings are fine. You should be more concerned about your anxiety and panic attacks and get your psychotherapy sessions and take zoloft as per recommendations. You shall feel better. Nothing is wrong in heart.
I hope it helps. Take good care of yourself and dont forget to close the discussion please.
Regards
Khan
All labs normal. No worries, focus on anxiety management
Detailed Answer:
Thank you for asking
I read your question and i understand your concern. The QTC you are worried is still in normal range and slight variation due to many errors including machine error can be the reason behind it.
I want you to know that
QTc is prolonged if > 440ms in men or > 460ms in women
QTc > 500 is associated with increased risk of torsades de pointes
QTc is abnormally short if < 350ms
A useful rule of thumb is that a normal QT is less than half the preceding RR interval
Aslo there are different ways to measure the QTC like bazette's. fradrecia, framingham and hodges etc. All of them are equally valid and may give slight variation. Bezette's is used commonly though.
Bazett’s formula is the most commonly used due to its simplicity. It over-corrects at heart rates > 100 bpm and under-corrects at heart rates < 60 bpm, but provides an adequate correction for heart rates ranging from 60 – 100 bpm.
At heart rates outside of the 60 – 100 bpm range, the Fredericia or Framingham corrections are more accurate and should be used instead.
If an ECG is fortuitously captured while the patient’s heart rate is 60 bpm, the absolute QT interval should be used instead!
Nut shell, all your readings are fine. You should be more concerned about your anxiety and panic attacks and get your psychotherapy sessions and take zoloft as per recommendations. You shall feel better. Nothing is wrong in heart.
I hope it helps. Take good care of yourself and dont forget to close the discussion please.
Regards
Khan
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Above answer was peer-reviewed by :
Dr. Chakravarthy Mazumdar
Answered by
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