Evidence
Original publication
Postema PG, Wilde AAM. The measurement of the QT interval. Reviews QT measurement and the common heart-rate correction formulae — Bazett (QT/√RR), Fridericia (QT/RR^⅓), Framingham (QT + 0.154·(1 − RR)), and Hodges (QT + 1.75·(HR − 60)) — and their behaviour at rates away from 60 bpm.
Current Cardiology Reviews, 2014
Validation
Vandenberk B, Vandael E, Robyns T, et al. Which QT correction formulae to use for QT monitoring? In a large cohort Fridericia and Framingham corrections predicted mortality best and misclassified fewer patients than Bazett, especially outside 60–80 bpm.
Journal of the American Heart Association, 2016
Guideline
Rautaharju PM, Surawicz B, Gettes LS, et al. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram, part IV (QT interval). Bands used here: men normal ≤ 430 ms, borderline 431–450, prolonged ≥ 451; women ≤ 450 / 451–470 / ≥ 471; QTc ≥ 500 ms flagged as markedly prolonged.
Circulation, 2009
Last reviewed: 2026-09
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