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For specialists
The scores and formulas most often needed in arrhythmology. The calculation runs in your browser: the data you enter is not sent anywhere.
Risk of stroke and thromboembolism in atrial fibrillation
Age
CHA₂DS₂-VA score
0/ 8
Low risk
OAC is usually not required for stroke prevention; keep reassessing risk factors.
Comparison with the old score
CHA₂DS₂-VASc (female sex +1): score 0. ESC 2024 does not take sex into account; the ACC/AHA 2023 guidelines still use VASc.
Source: ESC 2024 clinical guidelines on atrial fibrillation (Van Gelder I.C. et al., Eur Heart J 2024)
Risk of major bleeding on anticoagulants
HAS-BLED score
0/ 9
Low risk
Reassess the modifiable factors regularly.
Source: Pisters R. et al., Chest 2010;138:1093–1100; cited in the ESC 2024 guidelines
Using four formulas, with a rate-dependent recommendation
QTc, Bazett
447ms
Normal
If the heart rate is outside 60–90 /min, rely on the Fridericia result instead of Bazett.
| Bazett | 447 ms |
|---|---|
| Fridericia | 431 ms |
| Framingham | 431 ms |
| Hodges | 426 ms |
RR = 800 ms, rate 75 /min
Source: Bazett 1920; Fridericia 1920; Sagie (Framingham) 1992; Hodges 1983. Cut-offs: AHA/ACCF/HRS 2009, ESC 2022 (ventricular arrhythmias)
Cockcroft–Gault formula: used to choose the DOAC dose
CrCl
72mL/min
≥ 50 mL/min
Usually the dose is not changed because of renal function; also check the other criteria (age, weight).
Actual body weight is used. This is not eGFR: DOAC trials and labels use Cockcroft–Gault CrCl specifically.
Source: Cockcroft D.W., Gault M.H., Nephron 1976;16:31–41; EHRA 2021 practical guide on DOACs
Four methods for a 25 mm/s strip
Formula: 300 / number of large squares
Heart rate
75/min
Source: Standard ECG paper: 1 small square = 40 ms, 1 large square = 200 ms
Want to practice measuring QT? Open the ECG simulator