CardioNerds (Dr. Rick Ferraro and Dr. Dan Ambinder) join Dr. Sahar Samimi and Dr. Lorraine Mascarenhas from Baylor College of Medicine, Houston, Texas, at the Houston Rodeo for some tasty Texas BBQ and a tour of the lively rodeo grounds to discuss an interesting case full of clinical pearls involving a patient with nonbacterial thrombotic endocarditis (NBTE). Expert commentary is provided by Dr. Basant Arya. Episode audio was edited by CardioNerds Intern Dr. Bhavya Shah.

<figure class="wp-block-image size-full"><figcaption class="wp-element-caption">(Photo by Xu Jianmei/Xinhua via Getty Images)Xinhua News Agency via Getty Images</figcaption></figure>

We discuss a case of a 38-year-old woman with advanced endometrial cancer who presents with acute abdominal pain, found to have splenic and renal infarcts, severe aortic regurgitation, and persistently negative blood cultures, ultimately diagnosed with nonbacterial thrombotic endocarditis (NBTE). We review the definition and pathophysiology of NBTE in the context of malignancy and hypercoagulability, discuss initial evaluation and echocardiographic findings, and highlight important management considerations. Emphasis is placed on the complexities of anticoagulation choice, the role of valvular surveillance, and the need for coordinated, multidisciplinary care.  

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Pearls- Nonbacterial Thrombotic Endocarditis

1. Eliminate the Usual Suspects. NBTE is a diagnosis of exclusion! Always rule out infective endocarditis (IE) first with serial blood cultures and serologic tests. 

1. More than Meets the Echo. Distinguishing NBTE from culture-negative endocarditis can be tricky. Look beyond the echo—focus on clinical context (underlying malignancy, autoimmune issues) and lab findings to clinch the diagnosis. 

1. TEE for the Win… Mostly. While TEE is more sensitive than TTE, NBTE vegetations can be sneaky and may embolize quickly. Don’t hesitate to use advanced imaging (i.e., cardiac MRI, CTA) or repeat imaging if you still suspect NBTE. 

1. Choose your champion. In cancer-associated NBTE, guideline recommendations for anticoagulation choice are lacking. Consider DOACs and LMWH as agents of choice, but ultimately use shared decision-making to guide management. 

1. No obvious trigger? Go hunting for hidden malignancies or autoimmune disorders. A thorough workup is essential to uncover the driving force behind NBTE. 

Check out this state-of-the-art review for a comprehensive, one-stop summary of NBTE: European Heart Journal, 46(3), 236–245. Please note that the figures and tables referenced in the following notes are adapted from this review. 

notes- Nonbacterial Thrombotic Endocarditis

Notes were drafted by Dr. Sahar Samimi. 

1. What is nonbacterial thrombotic endocarditis (NBTE)?  

• NBTE, previously known as marantic endocarditis, is a rare condition in which sterile vegetations form on heart valves.¹ 

• It occurs most commonly in association with malignancies and autoimmune conditions (i.e, antiphospholipid antibody syndrome or systemic lupus erythematosus).¹ In addition, NBTE has been reported in association with COVID-19 infection, burns, sepsis, and indwelling catheters.² 

• Precise mechanisms remain unclear, but an interplay of endothelial injury, hypercoagulability, hypoxia, and immune complex deposition contributes to the formation of these sterile vegetations. ¹ 

1. How do we diagnose NBTE? 

• Physicians should have a high level of suspicion for NBTE in at-risk patients (e.g., with active malignancy) who present with recent or recurrent embolic events (i.e., stroke, splenic, renal, or mesenteric infarct, and acute coronary syndrome).¹ 

• Once vegetations are observed, the diagnosis of NBTE is focused on ruling out IE, followed by looking for the underlying etiology, if not already evident.¹ A focused clinical assessment, including a thorough history, physical exam, and relevant microbiological and serological tests, should aim to rule out IE using the modified Duke criteria.³ 

• Persistently negative blood cultures after adequate sampling increase the likelihood of NBTE but do not exclude culture-negative endocarditis. Vegetations found in patients with risk factors raise the suspicion for NBTE, whereas signs of systemic infection—such as ongoing fever, recent antibiotic exposure, or potential zoonotic sources—may point instead toward CNE.¹ 

• New diagnostic techniques, including specialized serology and metagenomic sequencing, have significantly enhanced our ability to detect elusive pathogens in CNE.¹ 

1. How should imaging be approached in suspected NBTE? 

• In cases of suspected endocarditis, guidelines from the American College of Cardiology, the A