This 66-year-old woman with a history of depression and chronic back pain was brought to the Emergency Department a few hours after having ingested large doses of acetaminophen, oxycodone and citalopram:

• Sinus rhythm, 82/min
• Minimal voltage criteria for left ventricular hypertrophy
• Prolonged QT (QT= 502 msec, QTc = 586 msec)

The antidepressant Citalopram has been proven to be associated with dose-related QT prolongation.  

The patient is admitted to hospital for treatment of drug overdose and for psychiatric assessment. Her citalopram is discontinued, and the following ECG is recorded 6 days after her admission:

• Sinus rhythm, 77/min
• Prolonged QT (QT = 434 msec, QTc = 492 msec)
• The QT prolongation was less marked than on admission 

The patient was discharged and referred to her family physician and psychiatry for further follow-up. It was advised that she should have a weekly ECG to access her QT, and that she not be restarted on citalopram, unless prescribed again by her psychiatrist (at low doses and with serial measurements of the QT interval).