Recurrent Embolic Stroke Due to Nonbacterial Thrombotic Endocarditis Followed by Transesophageal Echocardiography

A 44-year-old man with advanced gastric cancer visited our hospital because of a sudden onset of difficulty in speaking. He was diagnosed as having recent embolic strokes of bilateral middle cerebral artery territories (Figure 1A and B). Elevated plasma levels of D-dimer indicated ongoing hypercoagulation. Electrocardiography showed normal sinus rhythm. Transesophageal echocardiography revealed a 7-mm mobile isoechoic mass broadly attached to the left and noncoronary cusp of the aortic valve (Figure 2A and B). Infective endocarditis was ruled out by negative results in repeated blood cultures and by a normal inflammatory index. The patient developed nonbacterial thrombotic endocarditis (NBTE). Subsequently, anticoagulation was initiated with continuous intravenous infusion of heparin. On day 11, follow-up transesophageal echocardiography demonstrated that the mobile vegetation had shrunk to 5 mm with a decreased whole volume (Figure 2C and D and videos 1, 2, 3, and 4). At the same time, recurrent embolic stroke without symptoms was documented by follow-up magnetic resonance imaging (Figure 1C and D).

Nonbacterial thrombotic endocarditis, also known as marantic endocarditis associated with malignant or other debilitating systemic diseases, is sometimes difficult to confirm.¹ Most NBTE vegetations are smaller than 3 mm in diameter.² Transesophageal echocardiographic images are essential to detect NBTE vegetations because these images are superior to transthoracic echocardiographic images for identification of a cardiac embolic source.³ The NBTE vegetations are easily dislodged because there is little inflammatory reaction at the site of attachment, and thus the vegetations are a source of multiple organ embolism. Our case strongly suggested that vegetation had dislodged and thus impacted multiple emboli into the cerebral arteries. Magnetic resonance imaging findings of our case were compatible with those of a typical index stroke associated with NBTE, with multiple, widely distributed, small (<10 mm) and large (>30 mm) strokes that are different from those with infective endocarditis.⁴ In conclusion, transesophageal echocardiography is useful for the follow-up of NBTE to detect morphological changes in the vegetation as well as for the diagnosis of NBTE.