Tricyclic antidepressants, QT interval prolongation, and Torsade de Pointes

The authors postulate mechanisms linking tricyclic antidepressants, QT interval prolongation, torsade de pointes, and sudden cardiac death. Case reports identify amitriptyline and maprotiline as the tricyclic antidepressants most likely to provoke torsade de pointes. Risk factors of family history of congenital long QT syndrome, age, female sex, metabolic and cardiovascular disease, metabolic inhibitors, hypokalemia, drug overdose, and co-prescription of drugs associated with QT interval prolongation were found in cases of torsade de pointes associated with tricyclic antidepressants. Clinicians should be cautious when prescribing tricyclic antidepressants with other drugs, such as thioridazine, that are capable of prolonging the QT interval.