Concomitant Infectious and Noninfectious Endocarditis in Systemic Lupus Erythematosus

Abstract

Background Endocarditis continues to be a predominant cause of morbidity and mortality in patients with systemic lupus erythematosus (SLE). 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. Case Presentation An 18-year-old female with a past medical history of SLE with hemodialysis-dependent ESRD due to stage IV lupus nephritis presented with a 6-month history of progressive fatigue, dyspnea, and tachypnea. She was afebrile, tachycardic, and had a 1/6 rumbling diastolic murmur at the left lower sternal border. TTE 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. Because of her severe valvular disease and accompanying symptoms, the patient underwent a mitral valve replacement. Heavy growth of S. pyogenes from the mitral valve tissue specimen was demonstrated via ¬MALDI-TOF identification. Antibiotic susceptibility testing showed sensitivity to penicillin, and she was continued on IV penicillin G for 6 weeks following mitral valve replacement. Discussion NBTE is a non-infectious form of endocarditis that is most commonly associated with advanced malignancy (80%), followed by SLE. The modified Duke criteria can be helpful in discerning between infectious and non-infectious etiologies of endocarditis, and the absence of typical organisms on blood culture offers support for the diagnosis of NBTE. NBTE lesions on echocardiography are usually located at the basal, middle, or tip of leaflets and are heterogeneous in echogenicity, meanwhile, infective endocarditis lesions are more likely to occur at the line of leaflet closure and are more homogeneous in appearance. 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. Given that asymptomatic patients with SLE are not routinely screened for cardiac disease with echocardiography, it is possible that sterile, non-infectious endocarditis may precede infectious endocarditis in these patients. Increased awareness of endocarditis in patients with SLE is paramount as early diagnosis and treatment reduce mortality.