Abstract
Methadone is known to be associated with acquired long QT (LQT) syndrome and the subsequent development of Torsades de Pointes (TdP). We describe a case of acquired LQT and TdP in a patient taking methadone maintenance therapy (MMT) in conjunction with medications known to prolong QT interval, and in the setting of hypokalemia and hypomagnesemia. We highlight the risk of QT interval prolongation when polypharmacy and electrolyte imbalances coexist, demonstrate the importance of early and effective therapy of LQT and suggest potential future alternatives to MMT that appear to have less QT prolonging properties in patients with multiple risks for LQT and TdP.
Highlights
Acquired long QT interval (LQT) is a high-risk condition that can be associated with the ingestion of drugs that alter the action potential by different mechanisms [1]
We report a case in which the use of methadone, citalopram and a diuretic, in the setting of an electrolyte imbalance, led to the development of LQT and Torsades de Pointes (TdP)
This case reflects the risk of QT interval prolongation when methadone therapy, polypharmacy and electrolyte imbalances coexist in the same patient
Summary
Acquired long QT interval (LQT) is a high-risk condition that can be associated with the ingestion of drugs that alter the action potential by different mechanisms [1]. We report a case in which the use of methadone, citalopram and a diuretic, in the setting of an electrolyte imbalance, led to the development of LQT and TdP. He had prior history of hypertension, chronic back pain, depression, gastroesophageal reflux disease and a 35-pack year history of cigarette smoking He admitted to a previous history of heroin use, but adamantly denied any recent consumption and was receiving methadone for opiate addiction. The amiodarone further prolonged his QT interval and lead to recurrent TdP He was transferred to the catheterization laboratory, where only minor coronary artery disease was revealed. The patient was transferred to the Coronary Care Unit medications associated with prolongation of the QT interval were discontinued (methadone, citalopram and amiodarone). In follow-up clinic almost three months later, the patient had no recurrence of arrhythmias, and his ECG demonstrated a normal QTc of 434 ms (Figure 2, Panel B)
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