Unexpected Cardiac Thrombus in a Child With Severe Anemia and Morganella Bacteremia

To the Editors, A 21-month-old male presented to the clinic with pallor, anorexia, and irritability for 3 weeks and fever for 3 days. Complete blood count revealed hemoglobin of 1.6 g/dL, hematocrit of 7.7%, and platelets of 711,000 mm3. Personal and family history was negative for anemia and bleeding disorders. Thrombophilia workup was negative. He was admitted to the pediatric intensive care unit, where he received blood transfusions. Review of the patient’s diet revealed significant milk intake, suggesting a diagnosis of nutritional iron deficiency anemia (IDA). A blood culture collected on admission was positive for Morganella morganii. A chest radiograph showed cardiomegaly, and an echocardiography (ECHO) revealed a left ventricular (LV) focus, concerning for thrombus versus neoplasm versus vegetation (Fig. 1A). Cardiac magnetic resonance imaging confirmed a cardiac thrombus measuring 11 × 10 mm (Fig. 1B). He received empiric treatment for infective endocarditis (IE) with cefepime for 4 weeks. Cardiology and Hematology managed his anticoagulation. A repeat ECHO 3 weeks later showed a decreased size of the LV thrombus, measuring 6.5 × 4 mm. The patient was discharged on oral iron supplementation and rivaroxaban. ECHO, done after 6 weeks of anticoagulation, showed no thrombus, so rivaroxaban was discontinued.FIGURE 1.: A: Pediatric Echocardiogram. Hyperechoic heterogeneous mass in the left ventricular apex measuring 11 × 10 mm. B: Cardiac MRI. Well-circumscribed, homogeneous, oval mass adherent to the left ventricular apical myocardium and trabeculations. MRI, magnetic resonance imaging.Cardiac thrombi are extremely rare in children, typically occurring in those with central catheters, congenital heart defects, or inherited prothrombotic conditions. Thrombi in the LV are even rarer without severely decreased function and noncompaction. According to a large population-based study, thrombosis was present in 11.3% of patients with IDA versus 1.17% without IDA. The study concluded that the incidence of thrombosis was 6 to 10 times greater in patients with IDA, suggesting that IDA is a risk factor for thrombosis.1,2 The patient’s blood culture showed M. morganii, which could have led to hematogenous dissemination and seeding of the intracardiac thrombus, suggesting presumed IE. Infections can activate hypoxia-inducible transcription factors that increase the expression of coagulation factors and integrins, promoting thrombus formation.3 M. morganii is an opportunistic microorganism present in the human gastrointestinal tract and the environment. It can cause urinary tract infections in children. There has been 1 case report of M. morganii IE in a 72-year-old patient with multiple myeloma and valvular amyloidosis, and a second report in a healthy 34-year-old patient without valvular disease.4 M. morganii contains chromosomally encoded inducible AmpC production; however, the evidence of clinical failure rates with susceptible β-lactam therapy is limited compared with other species such as Enterobacter cloacae, Klebsiella aerogenes, or Serratia marcescens. In vitro activity of third-generation cephalosporins would suggest that the utility of these agents for significant infections should be avoided. Cefepime is recommended for infections from organisms at risk for AmpC production if the MIC for cefepime is 2 μg/mL or less.5 This case report adds to the limited literature of IE with cardiac thrombi in immunocompetent children without cardiac dysfunction. Anticoagulation therapy, intravenous antibiotics, and correction of IDA resulted in complete resolution of the thrombus. This raises the question of whether an ECHO is necessary when managing chronic anemia, even in immunocompetent pediatric patients.