Corrected QT Interval (QTc)
Corrects QT interval for heart rate to identify clinically significant QT prolongation and torsades risk
- Highest activation tier
- Recommended
- How it is scored
- Scored in code; a detected disagreeing draft value is flagged for correction
- Scoring type
- formula
- Care settings
- Any setting
When it activates
Scribeable activates a calculator from the encounter. The Corrected QT Interval (QTc) can activate when the transcript or pasted chart context documents any of these:
- QT prolongation on ECG
- Medication with QT-prolonging potential
- Antipsychotic monitoring
- Antiarrhythmic drug monitoring
- Syncope or arrhythmia workup
- Torsades de pointes risk assessment
A coded diagnosis can also activate it. ICD-10 prefixes carried by the registry: I45.81, I49, R94.31.
Inputs the note needs
2 inputs. Each is resolved from the transcript, the pasted chart context and charted labs; at this calculator’s tier a missing input is never requested, and a missing required input keeps the score out of the draft.
| Input | Type | Unit / options | Guidance |
|---|---|---|---|
| Measured QT interval in milliseconds | exam | ms | |
| Heart rate in bpm (or RR interval) | vital | bpm |
Scoring
Bazett: QTc = QT / √(RR interval in seconds). Fridericia: QTc = QT / ∛(RR). RR = 60/HR.
QTc (Bazett) = Measured QT interval in milliseconds / √(60 / Heart rate in bpm (or RR interval))
Interpretation
Normal QTc: <440 ms (men), <460 ms (women). Borderline: 440–470 ms (men), 460–480 ms (women). Prolonged: >470 ms (men), >480 ms (women). QTc >500 ms: significant torsades risk — review all QT-prolonging medications, check K/Mg. Fridericia is more accurate at extremes of heart rate.
Evidence
Sources carried in Scribeable's citation registry for this calculator; guideline version: AHA/ACC 2018.
- Rautaharju PM et al. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: corrected QT intervalAHA/ACC (QTc Correction) 2018 · 2009 · AHA/ACCF/HRS · Consensus · link last verified 2026-03-28
How Scribeable handles it in the note
When an encounter activates the Corrected QT Interval (QTc) (its highest tier is recommended), Scribeable does not ask you for missing inputs. The score is computed in code from whatever inputs resolve from the transcript, the pasted chart context or charted labs; a computed value is written into the draft only when every required input already resolves.
The score is computed in code from the resolved inputs, not recalled by the language model. If the draft states a Corrected QT Interval (QTc) value that disagrees with the computed one, the disagreement is flagged to the second drafting pass, which is instructed to correct the score and its interpretation before you see the note.
Classified as a deterministic formula: a spare suggestion is easy to ignore, so activation is permissive.
See it activate on your own encounter
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