Korean J Psychopharmacol.  2008 Mar;19(2):106-110.

A Case of QTc Interval Prolongation Associated With Quetiapine

• Lee SJ
• Kim HW

Abstract

The QT interval is a measure of the time between the start of the Q wave and the end of the T wave in the cardiac electrical conduction and has to be corrected for heart rate, namely, QTc. QTc interval prolongation can occur as a result of treatment with both conventional and novel antipsychotic medications; it is of clinical concern because it is associated with a potentially fatal ventricular arrhythmia, torsade de pointes. A 33-year-old female patient with schizophrenia developed a prolonged QTc interval while taking quetiapine. Her QTc returned to baseline levels when quetiapine was discontinued. The quetiapine-related QTc prolongation might have been associated with the use of a high dose quetiapine with rapid titration or prior use of ziprasidone, which is metabolized by the same cytochrome P450 enzyme that metabolizes quetiapine. The results suggest that it is important for physicians to identify pretreatment cardiac conduction abnormalities and other risk factors associated with QTc interval prolongation when prescribing quetiapine, especially high dosages or during the concomitant use of other P450 3A4 inhibitors. It is also important to check a baseline ECG before starting treatment.

Keyword

Quetiapine; QTc interval prolongation; Schizophrenia

MeSH Terms

Adult
Arrhythmias, Cardiac
Cytochrome P-450 Enzyme System
Dibenzothiazepines
Electrocardiography
Female
Heart Rate
Humans
Piperazines
Risk Factors
Schizophrenia
Thiazoles
Torsades de Pointes
Quetiapine Fumarate
Cytochrome P-450 Enzyme System
Dibenzothiazepines
Piperazines
Thiazoles