MDCalc

Tisdale Risk Score for QT Prolongation

Predicts risk of QT prolongation greater than 500 msec in hospitalized patients.

Launched during COVID-19 crisis.

This score was derived and internally validated for hospitalized patients, and may not predict outpatient risk of QT prolongation as accurately (but has not been studied in this population).

Age ≥68 years

Sex

Patient on loop diuretic

Potassium ≤3.5 mEq/L

Potassium should be potassium determined closest to EKG timing

Admission QTc ≥450 msec

Auto-calculated by EKG

Being admitted for acute myocardial infarction

Being admitted for sepsis

Being admitted for heart failure

Number of QTc-prolonging drugs given

If receiving ≥2 drugs, patient receives 3 points for 1 QTc-prolonging drug as well as 3 additional points for ≥2

Result:

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Advice

  • EKG should be repeated 8-12 hours after starting QT-prolonging drug to look for signs of QT prolongation, with closer monitoring if it is observed.

  • Correct electrolyte abnormalities and maintain serum potassium >4.0 mEq/L and serum magnesium >2.0 mg/dL.

Critical Actions

While the scope of Torsade de pointes (TdP) is outside the scope of this calculator, Advanced Cardiac Life Support (ACLS) protocols can be followed should this develop, including defibrillation for unstable patients.

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