SPC365

Endocarditis mimics: unraveling a diagnostic mystery in a prosthetic valve patient

Session: SESSÃO DE CASOS CLÍNICOS DE MIOCARDIOPATIAS, VALVULOPATIAS, DOENÇAS DO PERICÁRDIO, CARDIOPATIAS CONGÉNITAS
Speaker: Sofia Esteves

Congress: CPC 2025
Topic: F. Valvular, Myocardial, Pericardial, Pulmonary, Congenital Heart Disease
Theme: ---
Subtheme: ---
Session Type: Sessão de Casos Clínicos
FP Number: ---
Authors: Sofia Esteves; Ana Abrantes; Catarina Santos Gregório; Miguel Azaredo Raposo; Daniel Inácio Cazeiro; Marta Miguez Vilela; Pedro Simões Morais; Roberto Palma Dos Reis; Nuno Lousada; Luís Parente Martins; Fausto Pinto; Catarina Sousa

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<p style="text-align:justify"><span style="color:#000000"><span style="font-size:12pt"><span style="font-family:Aptos,sans-serif"><strong><span style="font-family:Calibri,sans-serif">Introduction:</span></strong><span style="font-family:Calibri,sans-serif"> Endocarditis mimics present a diagnostic challenge, particularly in patients with prosthetic valves and persistent fever. These cases require consideration of alternative diagnoses beyond infective endocarditis (IE).</span></span></span></span></p>

<p style="text-align:justify"><span style="color:#000000"><span style="font-size:12pt"><span style="font-family:Aptos,sans-serif"><strong><span style="font-family:Calibri,sans-serif">Case Presentation:</span></strong><span style="font-family:Calibri,sans-serif"> A 68-year-old male presented with a one-week history of fever and dyspnea. His medical history included surgical aortic valve replacement with a mechanical prosthesis for severe aortic stenosis and paroxysmal atrial fibrillation. Upon admission, physical examination revealed fever (38.5&deg;C), a midsystolic click,&nbsp;&nbsp;diastolic murmur along the left sternal border, and petechial lesions on the upper limbs. Laboratory tests showed elevated inflammatory markers (white blood cell count of 16&times;10?/L and C-reactive protein of 31.7 mg/dL). IE was suspected based on two minor Duke criteria, prompting blood cultures and empirical antibiotic therapy with ceftriaxone, ampicillin, and vancomycin. A transesophageal echocardiogram (TEE) showed an aortic periannular abscess. A total-body computed tomography (CT) scan ruled out embolic phenomena. Repeated blood cultures were negative, as were serologies for atypical pathogens (<em>Coxiella burnetii</em>, <em>Bartonella spp.,</em> and <em>Brucella spp)</em>. Testing for <em>Rickettsia conorii</em> showed high titers of IgM and IgG, deemed to be due to antibody cross-reactivity. After 33 days of antibiotic therapy, a repeat TEE showed persistent abscess formation, though reduced in size. The patient was transferred to a surgical center for prosthetic valve replacement evaluation.</span></span></span></span></p>

<p style="text-align:justify"><span style="color:#000000"><span style="font-size:12pt"><span style="font-family:Aptos,sans-serif"><span style="font-family:Calibri,sans-serif">A transthoracic echocardiogram (TTE) revealed an anechoic area consistent with a pseudoaneurysm. A repeat TEE showed thickening of the mitro-aortic trigone. Cardiac CT confirmed a pseudoaneurysm with approximately 1 cm, superior to the non-coronary cusp. </span></span></span></span></p>

<p style="text-align:justify"><span style="color:#000000"><span style="font-size:12pt"><span style="font-family:Aptos,sans-serif"><span style="font-family:Calibri,sans-serif">Despite six weeks of antibiotics, the patient remained febrile. He developed a pruritic rash, initially on the lower limbs and abdomen, rapidly spreading to the upper limbs and face after antibiotic administration. Dermatology and immunology consultations led to a switch in therapy to tigecycline. </span></span></span></span></p>

<p style="text-align:justify"><span style="color:#000000"><span style="font-size:12pt"><span style="font-family:Aptos,sans-serif"><span style="font-family:Calibri,sans-serif">Given the rash and persistent fever, fever, other than IE cause for this presentation was suspected, antibiotics were discontinued and revision with the Infectious diseases team was undertaken. A positron emission tomography (PET) scan revealed no inflammation around the prosthetic valve, ruling out active endocarditis. Upon further investigation, the patient revealed that his dog had recently been treated for <em>Rickettsia</em>. He was treated with doxycycline for five days, resulting in the resolution of the rash and fever.</span></span></span></span></p>

<p style="text-align:justify"><span style="color:#000000"><span style="font-size:12pt"><span style="font-family:Aptos,sans-serif"><strong><span style="font-family:Calibri,sans-serif">Discussion/Conclusions:</span></strong><span style="font-family:Calibri,sans-serif"> This case highlights the diagnostic challenge of prolonged fever in patients with prosthetic valves. It also emphasizes the importance of a detailed clinical history and multidisciplinary collaboration in uncertain diagnosis. </span></span></span></span></p>
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