Non-Bacterial Thrombotic Endocarditis: Rare but Critical – Case Study & Literature Review

Abstract

Non-bacterial thrombotic endocarditis (NBTE) is a rare, non-infective form of endocarditis marked by the deposition of sterile fibrin and platelets on cardiac valves. Though it remains under-recognized, NBTE can lead to significant morbidity, particularly in cancer patients and individuals with autoimmune disorders. This case study examines a patient with NBTE, delving into the diagnostic challenges, including the utility of advanced echocardiographic techniques, and the importance of timely intervention. The aim is to provide an overview of NBTE’s pathophysiology, diagnosis, and treatment while emphasizing the need for heightened clinical suspicion to improve outcomes.

Introduction

NBTE, or marantic endocarditis, is a rare disease seen almost exclusively in association with hypercoagulable states, such as malignancies and autoimmune diseases. In contrast to infective endocarditis, NBTE is non-infectious and is characterized by the formation of sterile vegetations on heart valves, typically in the setting of systemic illness. The difficulty in early diagnosis of the condition is its nonspecific presentation and is therefore one that often mimics the other cardiovascular or embolic diseases. This case study has highlighted the clinical presentation, diagnostic process, and therapeutic approach for NBTE, using a very recent patient and reviewing literature.

Patient Information

A 58-year-old female, presented to the emergency with acute neurological deficits in the form of slurred speech and left-sided weakness. Past medical history revealed metastatic ovarian cancer for which she was on chemotherapy. No previous history of infective endocarditis or recent surgeries was noted. She was afebrile with a normal white cell count, with the rest of her physical examination being significant for a systolic murmur over the aortic valve area.

Clinical Findings

Initial laboratory results were unremarkable except for elevated D-dimer levels. Blood cultures were negative, ruling out an active bacterial infection. A transthoracic echocardiogram (TTE) revealed a mass on the aortic valve, but the images were not conclusive. Given her underlying malignancy, there was suspicion of NBTE, prompting further diagnostic evaluation.

Timeline

1. Day 1: Presentation with neurological symptoms, and suspicion of a thromboembolic event.

2. Day 2: TTE shows an inconclusive mass on the aortic valve.

3. Day 3: Transesophageal echocardiogram (TEE) performed, confirming vegetations suggestive of NBTE.

4. Day 4: Anticoagulation therapy initiated after diagnosis.

5. Day 10: Follow-up imaging shows no new embolic events; patient remains stable.

Diagnosis

The diagnosis of NBTE was confirmed based on echocardiographic findings from TEE, which showed sterile vegetations on the aortic valve. Further investigations, including negative blood cultures and a history of ovarian cancer, supported the diagnosis. The patient had no fever or elevated inflammatory markers, ruling out infective endocarditis. Given the findings, NBTE related to her malignancy was considered the most likely diagnosis.

Follow-up and Outcome

After initiating anticoagulation with low-molecular-weight heparin, the patient’s neurological symptoms gradually improved. Follow-up echocardiography performed ten days later revealed no new thromboembolic events or changes in valve morphology. She remained on anticoagulation therapy and was scheduled for close monitoring to prevent further thromboembolic complications.

Discussion

NBTE is an extremely rare but dangerous condition that may lead to systemic embolization, including strokes, as described below. Pathophysiology is by way of deposition of fibrin and platelets at the cardiac valves in the absence of an active infection. Hypercoagulable states such as cancer, autoimmune diseases such as SLE, and chronic inflammatory conditions are all significantly associated with NBTE.

Diagnosis can be done with echocardiography, and TTE would be the preferred tool. Even though it is less sensitive than TEE, much less sensitive, in fact, to small vegetation. Visualization is superior with TEE, especially with more advanced three-dimensional and multiplanar reconstruction analysis that improves diagnostic accuracy.

Management of NBTE primarily consists of treatment of the underlying disorder and the institution of anticoagulation to prevent thromboembolic complications. Heparin rather than warfarin is preferred for use in patients with NBTE as the efficacy of the former appears more reliable in this condition. Management of tumor burden may also help decrease the likelihood of recurrence if caused by a malignancy.

Although the condition is not contagious, if left untreated, NBTE has a very poor prognosis, especially in cancer patients. Anticoagulation management and supportive care should be instituted promptly to reduce morbidity and mortality.

Patient Perspective

The patient was initially concerned about the possibility of a stroke due to her sudden neurological symptoms. After receiving a clear explanation of her condition and understanding the nature of NBTE, she expressed relief that it was not a bacterial infection and appreciated the timely medical intervention. She emphasized the importance of close follow-up and was compliant with anticoagulation therapy, grateful for the improved management of her symptoms.

Conclusion

NBTE is a challenging diagnosis, particularly in patients with predisposing conditions such as malignancy. This case highlights the importance of early recognition and the use of advanced echocardiographic techniques to improve diagnostic accuracy. With appropriate anticoagulation therapy and management of the underlying disease, patients can experience significant clinical improvement. Further research is needed to better understand the pathophysiology of NBTE and to optimize treatment protocols.

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