Table 1. Common clinical risk factors for drug-induced QT prolongation and TdP [19].

Female

Conditions predisposing to heightened QT prolongation and risk of arrhythmia

Heart disease

Congestive heart failure

Left-ventricular hypertrophy

Hours following conversion of atrial fibrillation to sinus rhythm

Congenital long-QT syndrome (may be clinically unrecognized)

Bradycardia and conduction disease

Increased drug bioavailability

Altered function of specific cytochrome P450 (CYP450) isoforms (for liver metabolized drugs) Genetic variants

Concomitant inhibitory drugs

Liver disease

Altered renal or liver function (for renally or hepatically excreted drugs)

Electrolyte imbalance

Hypokalaemia

Hypomagnesaemia

Hypocalcaemia (possible)

Administration of other drugs which might cause QT prolongation