Fridericia Corrected QT Interval (QTcF)
Corrects QT interval for heart rate using cube root formula. Preferred over Bazett at extremes of heart rate (tachycardia/bradycardia).
Score interpretation
QTcF within normal range (<430 ms men, <450 ms women).
→ No QT-prolonging risk. Continue drugs as prescribed. Repeat ECG if drugs changed.
Borderline QTcF. Monitor carefully.
→ Review QT-prolonging medications. Correct electrolytes (K⁺, Mg²⁺, Ca²⁺). Cardiology review if persistent.
Prolonged QTcF. Increased TdP risk.
→ Review and stop unnecessary QT-prolonging drugs. Electrolyte correction. Consider cardiology review.
QTcF ≥500 ms — high risk of Torsades de Pointes.
→ Stop QT-prolonging drugs immediately. Correct electrolytes urgently. Telemetry monitoring. Cardiology review. Consider IV magnesium sulfate if symptomatic.
Interpretation bands for the Fridericia QTc. Apply clinical judgement and local guidance.
References
- Fridericia LS. The duration of systole in an electrocardiogram in normal humans and in patients with heart disease. 1920. Ann Noninvasive Electrocardiol. 2003;8(4):343-351.
- Rautaharju PM et al. AHA/ACCF scientific statement on noninvasive risk stratification techniques for identifying patients at risk for sudden cardiac death. J Am Coll Cardiol. 2008;52(14):1179-1199.
Related
Curated clinical cross-links plus same-class fallbacks.
- Modified Sgarbossa's Criteria (Smith Modification) for MI in LBBB · ECG Interpretation
- Brugada Phenocopy Score · ECG Interpretation
- Wellens Syndrome ECG Pattern · ECG Interpretation
- Lead aVR Sign for Left Main / Proximal LAD Occlusion · ECG Interpretation
- de Winter ECG Pattern for Proximal LAD Occlusion · ECG Interpretation
- Acute Heart Failure · ESC 2021 Heart Failure Guidelines; NICE NG106
- NSTEMI / Unstable Angina · ESC 2020 NSTEMI Guidelines; NICE NG185
- New-Onset Atrial Fibrillation · ESC 2020 AF Guidelines; NICE NG196
- Hypertensive Emergency · ESC/ESH 2018 Hypertension Guidelines; NICE NG136
- Bradycardia Management · Resuscitation Council UK ABCDE; ESC 2021 Pacing Guidelines
- Ventricular Tachycardia / Fibrillation · Resuscitation Council UK ACLS; ESC 2022 Ventricular Arrhythmia Guidelines
Decision support only — verify against a current formulary, NICE, or your local guideline before clinical use.