Table 1

Patient risk factors for Torsades de pointes with drug-induced QT prolongation.10 14 15

Non-modifiablePotentially modifiable

  • Congenital long QT syndrome*

    • QT-prolonging drugs should not be used in these patients

  • Structural heart diseases, such as heart failure (low ventricular ejection fraction), left ventricular hypertrophy, and myocardial infarction

  • Thyroid disease (not treated); more common with hypothyroidism

  • Impaired hepatic or renal function (could affect drug metabolism)

  • Female sex

  • Age >65 years

  • Bradycardia

  • Uncorrected electrolyte disturbances (hypokalaemia, hypomagnesaemia, hypocalcaemia)

  • Recent cardioversion with a QT-prolonging drug

  • *Congenital long QT syndrome is rare (estimated prevalence: ~1 in 2000–2500 infants) but is associated with a risk of arrhythmia and premature sudden death.4