Atypical Infective Endocarditis Presenting With Euthermia and Right Lower Quadrant Abdominal Pain.

Infectious endocarditis (IE) is an infection of the heart's endothelial lining, often stemming from an underlying bacteremia. High-risk populations include intravenous substance users, individuals with structural heart disease, those with intravascular devices, and those with prosthetic heart valves. In the emergency department, IE is often suspected in patients with a fever, known risk factors, and unexplained systemic symptoms due to systemic thromboemboli. We present a case of atypical IE occurring in an afebrile 38-year-old woman with a remote history of intravenous drug use. The patient's clinical presentation was characterized by systemic inflammatory response syndrome, stabbing-like right lower quadrant abdominal pain radiating to the right lower back and the rest of the abdomen, malaise, fatigue, and an absence of a fever. A CT scan revealed a right renal embolism and an infarcted right kidney, prompting a bedside point-of-care echocardiogram that showed a large vegetation on the mitral valve, suggestive of IE with systemic thromboembolic disease. The patient received broad-spectrum antibiotics and antipyretics and ultimately underwent mitral valve replacement, with good recovery upon discharge. Patients with IE are at high risk for life-threatening complications due to tissue damage from systemic microemboli and sepsis. It is important to identify IE's atypical presentation and risk factors for early recognition, prompt point-of-care echocardiogram, and initiation of treatment. This is particularly important in the era of increased opioid use among our patient population which could potentially conceal an underlying fever.