QTc

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.

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.

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.