Abstract Body (Do not enter title and authors here): Background: Libman-Sacks endocarditis (LSE) is a rare, non-infective form of endocarditis, often associated with systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS). It is characterized by sterile, verrucous vegetations that typically affect the mitral and aortic valves. While mitral regurgitation and aortic regurgitation are more frequently reported, severe aortic stenosis (AS) as the primary manifestation of LSE is exceedingly rare, with a reported prevalence of only 1.1% among affected patients. Even more unusual is its presentation as the first sign of undiagnosed SLE in a male patient, given the strong female predominance of the disease, with a female-to-male ratio of approximately 8:1.

Case: A previously healthy 37-year-old male, presented with severe chest pain. A Transthoracic echocardiogram (TTE) revealed severe aortic stenosis (Figure1), with vegetations on the right coronary cusp (RCC) and non-coronary cusp (NCC) of the aortic valve. His left ventricular ejection fraction was reported as normal, and minimal pericardial effusion was also detected.
Infective endocarditis and pericarditis were suspected and he was started on analgesics and colchicine. Empirical antibiotic treatment was initiated, and blood cultures were collected. Transesophageal echo revealed vegetation on the RCC and NCC of the aortic valve, confirming endocarditis (Figure2).
His blood cultures returned with negative results, and an autoimmune workup was consistent with the diagnosis of SLE and APS (Table1).
A diagnosis of Libman-Sacks endocarditis was suspected as the underlying cause of the valvular disease. He was started on prednisolone, enoxaparin, hydroxychloroquine, warfarin, and aspirin. On follow-up six months later, TEE and TTE showed no significant change in the severity of his AS, nor the vegetation. Therefore, an aortic valve replacement was planned.

Discussion: This is a rare case of a male patient with no prior symptoms who presented with LSE as the first manifestation of SLE and APS. It involved severe aortic stenosis, a less common outcome, as LSE typically causes regurgitation.
Diagnosis was challenging due to the atypical presentation and initial suspicion of infection. Despite immunosuppressive treatment, the stenosis persisted, necessitating eventual aortic valve replacement. Early diagnosis and management of SLE and APS are crucial to reduce the risk of thromboembolic complications and potentially prevent irreversible organ damage.