Mitral valve aneurysm in endocarditis.

To the Editor: I read with interest the contribution by Cai et al in the “Images in Cardiovascular Medicine” section of the journal.1 They described a patient who developed severe aortic regurgitation and a mitral valve aneurysm 1 month after successful treatment of Streptococcus mitis endocarditis. The case presentation and the title implied that the mitral valve aneurysm was caused by the effect of severe aortic regurgitation on the mitral valve and not directly related to endocarditis. I am unaware of other cases of mitral valve aneurysm as a result of severe aortic regurgitation in the absence of endocarditis. On the other hand, mitral valve aneurysm is a well-known complication in patients with aortic valve endocarditis and is caused by the development of satellite infection on the anterior mitral leaflet.2,3 The vegetative process leads to inflammation and “softening” of the underlying tissue, leading to aneurysm formation, which can involve the aortic annulus, the intervalvular fibrosa, and the mitral valve.2,3 We have previously described a patient with mitral valve endocarditis who went on to develop mitral valve aneurysm despite successful treatment of the infection.4 At surgery, there was chronic inflammation with no evidence of acute infection, similar to the finding in the case of Cai et al. In short, I believe it is misleading to suggest that the mitral valve aneurysm developed as a consequence of severe aortic regurgitation alone, since this was much more likely a direct result of the infective process on the anterior mitral leaflet.