Hemodynamics

QTc (Framingham) Calculator

Heart-rate-corrected QT by a linear correction from the Framingham Heart Study, steadier than Bazett at fast and slow rates.

Reviewed by Alex G, BSN, RN, CEN, CCRN, CMC, NREMT-P · From the Reference tab of the app

Turn on JavaScript to use this calculator, or open it in the web app.

Formula

QTc = QT + 0.154 × (1 − RR), all in seconds
In ms: QTc = QT + 154 × (1 − RR in seconds)
RR (seconds) = 60 ÷ heart rate
Example: QT 400 ms at 90/min: RR 0.667 s, QTc = 400 + 154 × 0.333 = 451 ms (Bazett gives 490)

How it is used

• Derived by linear regression in 5,018 Framingham participants aged 28–62 without coronary disease; Bazett overcorrects at fast rates and undercorrects at slow ones (Sagie 1992).
• About 470 ms in men and 480 ms in women is the 99th percentile in healthy adults; over 500 ms is highly abnormal in either sex (Drew 2010).
• Fridericia and Framingham corrected for rate best in 6,609 patients in sinus rhythm under 90/min; use the formula your unit names, every time, so serial values compare (Vandenberk 2016; Drew 2010).

Key points

• A QTc over 500 ms or a rise of 60 ms on a QT-prolonging drug needs prompt action: tell the prescriber, look for interacting drugs, bradycardia and low potassium or magnesium, and keep a defibrillator at hand (Drew 2010).

Same formula as the app. Open it in the web app.

Related one-pagers

• Toxidromes and AntidotesQTc over 500 ms, torsades · Methadone, antipsychotics, citalopram, sotalol · Magnesium, potassium, overdrive pacing
• Rhythm GalleryQTc, ST segment, T and U waves; then name the rhythm and decide whether it explains the patient.
• CEN Mental Health: Crisis, Suicide Risk, Eating Disorders and AbuseAdmission supported by any of (SAHM 2022): HR under 50 awake or 45 asleep; BP under 90/45; T under 35.6 °C (96 °F); 75% of median BMI or less; orthostatic pulse rise over 40 (under 19 y) or over 30, or BP fall over 20 systolic or 10 diastolic; low K, Na or phosphate; long QTc; syncope; acute food refusal; suicidal thoughts.
• Blood Products and TransfusionCitrate binds calcium (long QTc, tetany, paresthesias): check ionized calcium

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For education and exam preparation only. Follow your institution’s protocols. For education and exam preparation only. Verify results independently and follow your institution’s protocols. Not a substitute for clinical judgment.