Acute ST-Segment Elevation Myocardial Infarction Following Intramuscular Diclofenac: A Case of Kounis Syndrome

Kounis syndrome (allergic myocardial infarction) is the rare occurrence of systemic anaphylaxis with spontaneous electrocardiographic changes in response to an exogenous agent. Often the syndrome is caused by a drug reaction involving drugs such as non-steroidal anti-inflammatory drugs, antibiotics, or opioids. There are a few reported cases in the literature regarding diclofenac-induced Kounis syndrome, and little is known about the management of this clinical entity. A case of Kounis syndrome with ST-elevation myocardial infarction secondary to intramuscular (i.m.) diclofenac in a patient with prior coronary artery bypass graft surgery is described in this report. Additionally, we discuss the pathophysiology, clinical presentation, and management of this rare clinical entity. As i.m. diclofenac is a commonly used drug in the emergency department, we urge emergency physicians to be aware of the existence of this potentially fatal diclofenac-related adverse drug effect. If Kounis syndrome is suspected, the emergency physician is advised to balance the benefit of epinephrine for the treatment of anaphylaxis with the small theoretical risk of increasing coronary vasospasm.