Klin Farmakol Farm. 2026;40(1):47-55 | DOI: 10.36290/far.2026.002

QT interval, etiopathogenesis of "torsade de pointes", and risk pharmacotherapy

Přemysl Mladěnka¹, Josef Kautzner²

¹ Farmaceutická fakulta v Hradci Králové, Univerzita Karlova

² Klinika kardiologie, Institut klinické a experimentální medicíny, Praha

The electrocardiographic QT interval reflects the duration of ventricular depolarization and repolarization. Prolongation of the QT interval occurs most commonly due to a slowdown in the late repolarization phase. There are inherited forms of long QT syndrome caused by mutations in genes that encode components of potassium or sodium channels, with a prevalence of about 1 in 2000 inhabitants. Additionally, there are acquired forms of long QT syndrome, which often result from the use of certain medications. These drugs either directly block the potassium channel Kv11.1 (hERG), or disrupt its trafficking. Prolonged QT interval is a key risk factor for developing a type of polymorphic ventricular tachycardia known as torsade de pointes (TdP), which can lead to ventricular fibrillation. The relationship between QT interval and TdP is complex and is influenced by other risk factors, including bradycardia, existing cardiovascular disease and/or diabetes mellitus, hypokalaemia, and hypomagnesemia. Women have a higher risk due to a lower repolarization reserve. Several groups of medications are associated with QT interval prolongation and TdP, and they are shortly summarized in this paper. They include antiarrhythmic drugs, quinolones, macrolides, azole antimycotics, antimalarial drugs, antipsychotic medications, antidepressants, antihistamines, opioid analgesics, and some targeted anticancer therapies. Lastly, the treatment of TdP and strategies for the prevention of its development in inherited forms are discussed.

Keywords: QT interval, arrhythmia, dysrhythmia, torsade de pointes, hERG channel, late repolarization.

Received: November 7, 2025; Revised: January 12, 2026; Accepted: January 19, 2026; Published: April 20, 2026  Show citation