What is QTc?
QTc is the QT interval corrected for heart rate. It helps assess repolarization abnormalities and arrhythmia risk.
How to calculate
Measure QT and RR (or heart rate). The calculator applies Bazett, Fridericia, Hodges, and Framingham formulas and compares results with reference ranges.
Limitations
QTc varies by formula, heart rate, and measurement quality. Drugs, electrolytes, and disease affect QT; use clinical judgment and repeat ECGs when needed.
Frequently Asked Questions
Which formula should I use?
Bazett is common but can over-correct at high heart rates. Fridericia or Framingham are often preferred in tachycardia; follow local guidance.
What QTc is considered prolonged?
Common thresholds are >450 ms in men and >460 ms in women; >500 ms indicates higher risk.
Why do my results differ between formulas?
Each formula corrects heart rate differently, so QTc can vary. Small changes in QT or RR also change the result.
Can I use heart rate instead of RR?
Yes. If RR is not provided, the calculator derives RR from heart rate (RR = 60/HR).