Loperamide-induced cardiogenic syncope: a case report of a life-threatening presentation of an over-the-counter drug

BACKGROUND: Loperamide at supratherapeutic doses can cause cardiac toxicity, presenting as cardiogenic shock, prolonged QT, malignant arrhythmias, or in severe cases sudden cardiac death. Surreptitious loperamide use is difficult to diagnose. We present an interesting case of loperamide use presenting with polymorphic ventricular tachycardia, cardiogenic shock. CASE SUMMARY: A 25-year-old female presented with multiple syncopal episodes for 12 months with an electrocardiogram showing a Brugada-like pattern for which she underwent implantable cardioverter-defibrillator placement. One day following the procedure, she developed cardiogenic shock and was transferred to our tertiary care centre. Extensive workup was unrevealing. She responded well to supportive management, recovering from shock and was transferred to the floor. Unfortunately, she again developed cardiogenic shock, ultimately leading to cardiac arrest. Given the unclear cause for her cardiovascular symptoms, futher medication history was obtained. It was revealed that she was taking 100–150 tablets of loperamide per day. The decision was made to treat with intralipid emulsion therapy empirically given the strong suspicion for loperamide toxicity. The patient recovered well with supportive care. Loperamide levels returned elevated at 190 ng/mL. Repeated studies showed improvement of the conduction block, resolution of arrhythmias, and recovery of right and left ventricular function. DISCUSSION: Acute loperamide toxicity can present as biventricular failure, with difficult-to-control arrhythmias. It requires a high index of suspicion. Treatment for loperamide toxicity is mainly supportive, lipid emulsion therapy can be considered in severe or refractory cases.