Abstract Hemophagocytic lymphohistiocytosis (HLH) is a life threatening hyperinflammatory syndrome that may follow infection, malignancy, or autoimmune disease. Secondary HLH carries a mortality rate of 30-40% within 2 months and overall 50-60% in ICU cohorts. This is in part due to delayed diagnosis, with one case series showing a median time to diagnosis of 20 days, resulting in irreversible multi-organ damage. We present a case of secondary HLH after abrupt cessation of immunosuppression in the setting of late presenting myocardial ischemia. A 67-year-old woman with RA on methotrexate and rituximab presented with six days of worsening chest pain. Laboratory evaluation revealed high-sensitivity troponin 7689 ng/L and lactate 2.7 mmol/L. Electrocardiography showed lateral T-wave inversions. CT imaging excluded pulmonary embolism but identified a new ventricular septal defect (VSD), later confirmed on point-of-care ultrasound. Emergent coronary angiography revealed an 80% mid-left anterior descending (LAD) artery lesion, an occluded diagonal branch (D1), VSD, and ejection fraction of 45%. An Impella CP device was placed and later upgraded to Impella 5.5 due to worsening cardiogenic shock. The patient developed suction events and hypervolemia requiring right-sided Impella placement for biventricular support.After two weeks of stabilization, she underwent VSD repair and coronary artery bypass grafting (LIMA to D1). Postoperatively, she developed hypotension, elevated lactate, worsening right ventricular failure, acute kidney injury necessitating renal replacement therapy, and pancytopenia requiring transfusions. Given her history of autoimmune disease and immunosuppression withdrawal, secondary HLH was suspected. Laboratory studies showed ferritin 32,155 ng/mL, triglycerides 195 mg/dL, fibrinogen 148 mg/dL, and fever of 102.9 °F, yielding a HScore of 244 (99% probability of HLH). Intravenous stress dose steroids were initiated, with positive hemodynamic response. CD25 returned positive, confirming HLH. This case illustrates secondary HLH precipitated by abrupt immune reconstitution following cessation of methotrexate and rituximab in a patient with RA. This case illustrates secondary HLH precipitated by immune reconstitution following abrupt cessation of methotrexate and rituximab in a patient with rheumatoid arthritis after CABG. The postoperative fever, cytopenias, and multiorgan failure resembling sepsis, but an HScore of 244 (99% probability) confirmed HLH, leading to corticosteroid initiation with clinical improvement. This case underscores the importance of anticipating HLH as a potential postoperative complication in immunosuppressed patients undergoing major surgery, where immune rebound can trigger a cytokine storm. Early use of the HScore in patients with unexplained fevers or cytopenias may facilitate timely recognition and improve outcomes in this life-threatening syndrome. This abstract is funded by: None
Tran et al. (Fri,) studied this question.