S2744 Loperamide-Induced Ventricular Fibrillation Cardiac Arrest in the Setting of Recently Diagnosed Ulcerative Colitis

Abstract

Introduction: Loperamide is a peripheral mu opioid receptor agonist that inhibits intestinal peristalsis and decreases fluid and electrolyte loss. While typically used over-the-counter for diarrhea, it may cause cardiotoxicity at higher dosages, leading to arrhythmia and cardiac arrest. Case Description/Methods: A 36 year-old female with a recent diagnosis of ulcerative colitis, presented with unresponsiveness while eating dinner. Cardiopulmonary resuscitation was initiated by family, found to be in ventricular fibrillation by paramedics. Return of spontaneous circulation was achieved after one defibrillation and administration of epinephrine. Upon admission to the intensive care unit, she developed torsades de pointes leading to recurrent ventricular fibrillation cardiac arrest, requiring 12 defibrillations and subsequent esmolol and lidocaine infusions. Computed tomography pulmonary angiogram was unremarkable for pulmonary embolism, and transthoracic ultrasound revealed no structural abnormalities. Cardiac MRI had no evidence of acute myocarditis or infiltrative cardiomyopathy. Cardiac catheterization revealed nonobstructing coronary arteries. For secondary prevention, an implantable cardiac defibrillator was placed. Upon further discussion after unplanned self-extubation, patient disclosed that she had been overutilizing loperamide at about 16 mg daily to help control her frequent episodes of diarrhea. (Figure) Discussion: Loperamide may act similar to antiarrhythmic medications, with dose dependent effects causing ventricular instability. Blockage of sodium channels prolongs the QRS complex causing polymorphic ventricular tachycardia, which may develop into torsades de pointes, ventricular fibrillation and cardiac arrest. Loperamide may be dosed over-the-counter up to 8 mg per day. While the half-life of loperamide is 9 to 14 hours, it may be greater than 40 hours at 16 mg doses, likely due to decreased peristalsis that slows its rate of absorption. Typical management of QTc prolongation arrhythmias due to medications may be refractory in loperamide-induced cardiotoxicity, including sodium bicarbonate, magnesium sulfate, amiodarone and defibrillation. Cardiac stabilization may not be obtained for up to 5 days. While most cases of loperamide-induced cardiotoxicity have been related to alleviating symptoms of opioid withdrawal or causing euphoria, our patient exemplifies an attempt to control symptoms of new onset Ulcerative Colitis.Figure 1.: Telemetry strips showing polymorphic ventricular tachycardia (A) inducing ventricular fibrillation (B).