QTc 405 ms is Normal
Your QTc of 405 ms falls well within the normal range and requires no intervention or concern. 1
Normal QTc Reference Values
The American College of Cardiology defines normal QTc intervals as:
Your QTc of 405 ms is 45-55 ms below the upper limit of normal, placing you comfortably in the normal range regardless of gender. 1
Understanding Your Values
QT interval (356 ms): This is the uncorrected measurement that varies with heart rate. 1
QTc interval (405 ms): This is the heart rate-corrected value that provides standardized assessment. 1 The QTc is what matters clinically, as it accounts for the effect of heart rate on ventricular repolarization. 1
Clinical Context
Your QTc is not only normal but actually falls in a very safe zone:
- Short QT threshold: ≤390 ms (you're above this) 1
- Normal range: 390-450 ms for men, 390-460 ms for women 1
- Borderline prolonged: 450-480 ms (you're well below this) 1
- Abnormally prolonged: ≥450 ms in men, ≥460 ms in women 1
- High-risk threshold: >500 ms (associated with torsades de pointes risk) 1, 2
Important Caveats
Measurement accuracy matters: Ensure the QTc was calculated using an appropriate correction formula (Fridericia's formula is more accurate than Bazett's, especially at heart rates >80 bpm). 1 Bazett's formula can artificially prolong QTc values, potentially causing unnecessary concern. 3
Time of day variation: QTc intervals naturally vary throughout the day, with values typically longer during sleep and peaking shortly after awakening. 4 However, even accounting for this physiologic variation, your value of 405 ms remains solidly normal. 4
No follow-up needed: With a QTc of 405 ms, you do not require serial ECG monitoring, medication adjustments, or cardiology referral based on this value alone. 1, 2