(1671) A Unique Case of Anaphylactic Shock After Exposure to a Gadolinium-Based Contrast Agent

Introduction: Gadolinium-based contrast agents (GBCAs) have been in use for over 30 years and typically have an excellent safety record. Studies have shown that the overall adverse event rate ranges between 0.07% and 2.4%. Allergic-like reactions, in particular, are rarely observed and are estimated to occur in about 0.004 to 0.7% of patients after exposure to GBCAs. We present a case of immediate allergic reaction post-exposure to a GBCA resulting in anaphylactic shock and cardiac arrest.

Description: A 52-year-old man with a history of cardiomyopathy presented to the hospital for a scheduled cardiac MRI. He received gadobenate dimeglumine (a type of GBCA) and shortly after developed dyspnea, chest pain, hypotension, and tachycardia. Physical exam was significant for labored respirations along with a new-onset erythematous rash on the face, neck, and upper chest. The patient quickly became unresponsive with loss of pulse, prompting initiation of CPR with the return of spontaneous circulation after one round. He was then admitted to the ICU for treatment of anaphylactic shock. He received high-dose methylprednisolone, diphenhydramine, famotidine, intramuscular epinephrine and started on an epinephrine drip. He was stabilized after a few hours and discharged home with close follow-up with his PCP.

Discussion: GBCAs adverse events are categorized into two categories. The first and most common subtype is Type A which generally consists of gastrointestinal upset, myalgia, and arthralgias. Some cases evolve into bradycardia and hypotension, which makes it challenging to distinguish from allergic reactions. The other category includes hypersensitivity reactions like urticaria, angioedema, and anaphylaxis. These usually occur within seconds or minutes after the injection. Severe life-threatening reactions occur in less than 0.01% of cases. Patients with a history of anaphylaxis to GBCAs have a recurrence risk of about 30%, and current guidelines recommend switching the type of GBCA used along with premedication with a corticosteroid and antihistamine if injection of GBCAs is necessary. Our case highlights the importance of awareness of the potential severity of hypersensitivity reactions to GBCAs, even in the context of their rarity.