Loperamide-induced ventricular tachycardia storm

Abstract

Loperamide is an over-the-counter, peripherally-acting, μ-opioid receptor agonist commonly used in the treatment of diarrhoea. It has increasingly been recognised as a potential drug of misuse, having previously been thought to have low potential for abuse owing to its low bioavailability and poor penetration of the central nervous system. High doses can result in life-threatening cardiac-toxicity. We present a case of a young woman who had been self-treating her depression with high doses of loperamide for one year, who then presented to hospital with syncope secondary to ventricular tachycardia (VT). While in the emergency department (ED) the patient had monomorphic pulseless VT requiring electrical cardioversion multiple times. Transfer to a tertiary cardiac centre was immediately arranged after she was stabilised and intubated. This complicated the diagnostic process as a thorough history could not be obtained on arrival to the tertiary centre, which meant the loperamide misuse only came to light multiple days into admission, after the patient was extubated. The final diagnosis of loperamide-induced secondary long-QT syndrome was made and the patient made a full recovery.

Keywords: loperamide; ventricular tachycardia.

Figure 1.. Admission electrocardiogram (ECG) demonstrating a sinus rhythm, right-axis deviation, left posterior hemi-fascicular block and a prolonged QTc interval

Figure 2.. ECG showing non-sustained polymorphic ventricular tachycardia