From the Guidelines
The normal QTc interval in males is less than 430 ms or less than 450 ms according to different studies 1.
Key Points
- The QTc interval is considered normal at less than 430 ms in males and less than 450 ms in females, as recommended by the FDA 1.
- A QTc interval of more than 450 ms in males is considered prolonged, and more than 460 ms in females is also considered prolonged 1.
- The Fridericia formula is recommended by the FDA for heart rate correction, which divides the QT interval by the cubic root of the RR interval 1.
- The Bazett’s formula is also commonly used, which divides the QT interval by the square root of the RR interval 1.
- It is essential to consider the gender difference in QTc interval, as females tend to have a longer QTc interval than males, especially in younger adults 1.
- The upper normal limit for QTc interval in males is generally considered to be less than 450 ms, while in females it is less than 460 ms 1.
From the Research
Normal QT Interval Corrected (QTc) in Males
The normal QT interval corrected (QTc) in males can vary depending on the formula used and the individual's age.
- According to the study 2, the upper normal limits of corrected QTc for males using different formulas are:
- Bazett: 483 ms
- Fridericia: 460 ms
- Framingham: 457 ms
- Hodges: 457 ms
- The study 3 established criteria for prolonged QTc using formulas that minimize QTc bias at the upper normal limits, and found that:
- For men aged < 40 years, the upper normal limit for QTc is 430 ms
- For men aged 40 to 69, the upper normal limit for QTc is 440 ms
- For men aged ≥ 70 years, the upper normal limit for QTc is 455 ms
- The study 4 found that the mean QTc interval for men is 434 +/- 12 ms, and the 95% upper confidence limit for the mean 24-h QTc interval is 439 ms for men.
- The study 5 compared QTc measurements on ECG and 24-hour Holter monitor, and found that the mean QTc interval via the Bazett formula was 0.40 s, while the mean QTc interval via the Fridericia formula was 0.38 s.
- The study 6 found that the corrected QT interval (QTc) exceeded 440 ms in 2.3% of children and adolescents, and that starting from the age of 8 years, girls had longer QTc than boys (454.1 +/- 15.2 ms vs 438.3 +/- 8.4 ms, respectively).