A 60-year-old woman developed a fever of >38 C and oral antimicrobial therapy was started. However, the fever lasted for 1 month and echocardiography revealed a large mass in the left atrium. She was transferred to our hospital for surgery in December 2018, before the COVID-19 pandemic outbreak. The patient was not immunocompromised, had no recent dental history, and had no other apparent risks.
On admission, her body temperature was 37.4 C, blood pressure was 113/67 mm Hg, heart rate was 104 beats/min and regular, and blood oxygen saturation was 97% on room air. Respiratory and heart sounds were normal and tumor plop sounds were not detected. No neurological deficits were observed.
Laboratory investigation showed an elevated white blood cell count of 14,300/microL and C-reactive protein concentration of 16.4 mg/dL. Her hemoglobin concentration was low at 9.7 g/dL, but hepatic and renal functions were normal. She had elevated concentrations of N-terminal pro-brain natriuretic peptide (784.8 pg/mL; reference range, 0-125 pg/mL), soluble interleukin (IL)-2 receptor (1590 U/mL; reference range, 121-613 U/mL), and IL-6 (73.3 pg/mL; reference range, 0.0-4.0 pg/mL). She also had elevated concentrations of neuron-specific enolase (24.6 ng/mL; reference range, 0-15 ng/mL) and CA125 (44.4 U/mL; reference range, 0-35 U/mL). Before antimicrobial administration, a blood specimen was collected for culture although Gram staining was not performed immediately after sampling.
An electrocardiogram showed normal sinus rhythm. Echocardiography revealed a 71- x 32-mm left atrial tumor protruding into the left ventricle during diastole (Figure 1). Normal left ventricular function and mild tricuspid regurgitation with a pressure gradient of 35 mm Hg were also noted. Magnetic resonance imaging showed hyperacute microinfarcts in the left temporal lobe and multiple old lacunar infarcts.
We diagnosed the patient with a left atrial myxoma, and surgery was performed the day after admission. Considering the possibility of infective endocarditis, intravenous ceftriaxone was started upon admission.
Surgery was performed through a median sternotomy with cardiopulmonary bypass. After obtaining cardiac arrest, right-sided left atriotomy was performed. A dark red jelly-like tumor (6.0 x 3.5 x 2.8 cm) with an irregular surface and a 1 cm stalk was attached caudal to the fossa ovalis (Figure 2). The tumor was removed along with the endocardium of the attached area. Many fibrin clots were observed on the posterior mitral leaflet and posterior wall of the left atrium, and they were scraped off as much as possible (Supplemental Material:Video 1). Intraoperative transesophageal echocardiography showed no mitral regurgitation, shunt flow, or residual tumor.
The patient's postoperative course was uneventful. Her fever subsided quickly after the surgery. Her IL-6 concentration decreased to 7.3 pg/mL on postoperative day (POD) 10. On the day after surgery, her preoperative blood culture exhibited growth of Gram-positive cocci, which were identified as Streptococcus vestibularis on POD 4. All blood cultures taken intraoperatively and postoperatively were negative.
Histopathological examination of the removed mass showed cuboidal cells, spindle-shaped cells, and stellate cells scattered on the background of a myxomatous matrix, and immunohistochemistry was positive for calretinin. The tumor surface was covered with fibrin and bacterial masses (Figure 3). These findings were compatible with a diagnosis of infected cardiac myxoma.
Because there are no guidelines for infected cardiac myxoma, we used the antibiotic therapeutic regimen described in the guidelines for infective endocarditis. Intravenous ceftriaxone was continued for 4 weeks after surgery. After intravenous ceftriaxone was switched to oral ampicillin, the patient was discharged home on POD 31. The oral antimicrobial therapy was discontinued 6 months postoperatively. As of the 21st postoperative month, the patient had no recurrence of infection, and no tumor or cerebral aneurysm was detected.