Marantic (nonbacterial thrombotic) endocarditis

The author: Professor Yasser Metwally

http://yassermetwally.com

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INTRODUCTION

December 30, 2009 —  This disorder is characterized by platelet fibrin thrombi that are deposited most commonly on either the aortic or mitral valve and have been termed “verrucous vegetations.” There is a clear association with hypercoagulable conditions and advanced malignancy. It often presents with arterial cerebral embolism. This risk of the disorder is roughly 1% of all cancer patients,[1] but it accounts for up to 20% to 30% of stroke in patients with cancer. [2,3] Characteristics of this uncommon disorder are listed in Box 1.

Box 1. Characteristics of marantic (nonbacterial thrombotic) endocarditis

1. Associated with sterile platelet-fibrin thrombi on heart valves 2. Most commonly affects the aortic and mitral valves 3. Associated with advanced malignancies and hypercoagulable states 4. Seen in approximately 1% of malignancies and most commonly associated with adenocarcinoma of either the pancreas, lungs, or stomach 5. Accounts for up to 20% to 30% of stroke in cancer patients 6. Often associated with other manifestations of hypercoagulation, such as venous thrombosis and disseminated intravascular coagulation 7. Transesophageal echocardiograpy is the most sensitive imaging device for detection of the verrucous vegetations on affected heart valves 8. Evaluation for malignancy or a hypercoagulable state is indicated when such vegetations are detected if such a condition has not already been found 9. Anticoagulant therapy may have some benefit for the associated hypercoagulable condition, but effective treatment of the underlying condition has the greatest potential for longer-lasting benefit

The identification of associated conditions, such as advanced malignancy or hypercoagulable condition, in a patient with stroke should lead to investigation for possible noninfectious valvular vegetations on the left side of the heart. The most sensitive study in this regard is transesophageal echocardiography (TEE), with one study reporting a yield of 18% in cancer patients with cerebral ischemia. [2] If such vegetations are detected in a stroke patient with negative blood cultures and no obvious associated condition then evaluation for occult malignancy or clotting disorder, such as disseminated intravascular coagulation, is indicated. [4] There is a tendency to use anticoagulant therapy in such a clinical setting, especially when there is clearly established thrombotic coagulopathy, although controlled clinical studies are lacking and there is concern over the potential for hemorrhagic complications. [5]

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References

1. Lopez JA, Ross RS, Fishbein MC, et al. Nonbacterial thrombotic endocarditis: a review. Am Heart J. 1987;113(3):773–778.
2. Macdonnell RA, Kalnis RM, Donnan GA. Non-bacterial thrombotic endocarditis and stroke. Clin Exp Neurol. 1986;22:123–132.
3. Dutta T, Karas MG, Segal AZ, et al. Yield of transesophageal echocardiography for nonbacterial thrombotic endocarditis and other cardiac sources of embolism in cancer patients with cerebral ischemia. Am J Cardiol. 2006;97(6):894–898.
4. Graus F, Rogers JB. Cerebrovascular complications in patients with cancer. Medicine (Baltimore). 1985;64(1):16–35. 
5. Rogers LR. Cerebrovascular complications in cancer patients. Neurol Clin. 2003;21(1):167–192.