Occult Presentation of Infective Endocarditis in Systemic Lupus Erythematosus.

Abstract

To the Editors: Endocarditis continues to be a predominant cause of morbidity and mortality in patients with systemic lupus erythematosus (SLE), particularly those who are hemodialysis-dependent.1 Given that patients with SLE are at risk for both nonbacterial thrombotic endocarditis (NBTE) and infective endocarditis, the distinction between etiologies is critical for providing appropriate therapy; however, this continues to pose a diagnostic challenge. We present a case of an 18-year-old female with combined NBTE and occult Streptococcus pyogenes (S. pyogenes) infective endocarditis and provide a brief review of infectious and noninfectious etiologies of endocarditis. An 18-year-old female with a past medical history of SLE (diagnosed in 2016) with hemodialysis-dependent end stage renal disease due to stage IV lupus nephritis presented with a 6-month history of progressive fatigue, dyspnea, and tachypnea. At the time of her admission, she was on hydroxychloroquine 200 mg and methylprednisolone 35 mg and rheumatologic labs demonstrated anti-dsDNA titer of > 1:640 with normal C3 and C4. She had WBC 13,600/µL, hemoglobin 15.2 g/dL, hematocrit 47.2% and platelets 80,000. She was afebrile, tachycardic, and had a 2/6 blowing systolic murmur and 1/6 rumbling diastolic murmur at the left lower sternal border. Trans-thoracic echocardiography revealed severe mitral stenosis and thickened mitral valve leaflets with severely restricted mobility and a mobile, echogenic mass on the atrial aspect of the anterior leaflet (Fig. 1A and B). There was moderate tricuspid valve stenosis and tricuspid valve regurgitation. Because of her severe valvular disease and accompanying symptoms, the patient underwent a mitral valve replacement as well as a tricuspid valvuloplasty. On inspection, the anterior leaflet of the mitral valve was massively thickened and was filled with granular and purulent material (Fig. 1C and D). Heavy growth of S. pyogenes from the mitral valve tissue specimen was demonstrated via matrix-assisted laser desorption/ionization-time of flight identification. Antibiotic susceptibility testing showed sensitivity to penicillin, and she was continued on IV penicillin G for 6 weeks following mitral valve replacement.FIGURE 1.: TEE and intraoperative images. A: Mid-esophageal 4-chamber view with thickened mitral valve leaflets (arrow). B: Mid-esophageal long-axis view with mobile, echogenic mass on the atrial aspect of the anterior leaflet (arrow). C: Intraoperative image demonstrating extensive mitral valve endocarditis with active necrosis and thickened anterior mitral valve leaflet (arrow). D: Cheese-like discharge from anterior mitral valve leaflet (arrow). TEE, trans-esophageal echocardiography.Distinguishing between infectious and noninfectious etiologies of endocarditis in patients with SLE is often difficult as these conditions may share many similar features. NBTE is a noninfectious form of endocarditis that is most commonly associated with advanced malignancy (80%), followed by SLE.2 The inciting pathology behind NBTE is unclear; however, it appears that circulating cytokines such as tumor necrosis factor or interleukins play a critical role in the development of a hypercoagulable state which predisposes to endothelial injury. The modified Duke criteria can be helpful in discerning between these etiologies, and the absence of typical organisms on blood culture offers further support for the diagnosis of NBTE.3 NBTE lesions on echocardiography are usually located at the basal, middle, or tip of leaflets and are heterogeneous in echogenicity, meanwhile, infective endocarditis lesions more likely occur at the line of leaflet closure and are more homogeneous in appearance.4 Although the prevalence of NBTE is reported to be 40%–60% by autopsy, it is only definitively diagnosed in 4%–6% of patients with SLE due to the predominantly asymptomatic disease presentation and the need for a pathologic specimen.5 Given that asymptomatic patients with SLE are not routinely screened for cardiac disease with echocardiography, it is possible that sterile, noninfectious endocarditis may precede infectious endocarditis in these patients. In the setting of cardiac findings, increased awareness of endocarditis is paramount as early diagnosis and treatment reduce mortality in patients with SLE, particularly those undergoing immunosuppressive therapy.5