Mitral valve aneurysm (MVLA) is a rarely encountered pathology with an estimated incidence of 0.03% and most commonly seen as a complication of infective endocarditis [1-3]. Other causes include connective tissue disorders, rheumatic heart disease and aortic regurgitation [4-6]. Typically MVLA is diagnosed via echocardiography, however as technology evolves, this entity may be encountered with other imaging modalities. We present two cases of mitral valve aneurysm: the first detected on dynamic cardiac computed tomography (CT); and the second on echocardiogram. The purpose of this case report is to review the CT and echocardiographic appearances of this rare entity thereby improve awareness amongst the cardiovascular imaging community.

Case 1: An 89-year-old female presented with progressively worsening dyspnoea on exertion. Her clinical examination was normal apart from an ejection systolic murmur on auscultation. She was considered as candidate for transcatheter aortic valve implantation (TAVI) and underwent work-up with echocardiogram, CT angiography as well as multiphase acquisitions of the heart through all phases of the cardiac cycle.

Her echocardiogram reportedly demonstrated mitral valve prolapse (this was unavailable for review). The cardiac CT demonstrated normal cardiac function with an ejection fraction of 52%.  Apart from a benign basal septal bulge, no significant myocardial hypertrophy was demonstrated. A focal outpouching of the anterior mitral leaflet extending into the left atrium, filling in systole and collapsing in diastole was present (Fig 1a, b, c; online video files). No evidence of leaflet vegetations or nodules was demonstrated. Coaption of the mitral leaflets appeared satisfactory. A membranous septal aneurysm was also present which extended into the right ventricle – this was considered a relative contra-indication to the TAVI procedure. The patient was subsequently lost to follow-up.

Case 2: A 48-year-old woman presented to her local emergency department complaining of fevers, myalgia/arthralgia, right shoulder pain and headache. This was thought to represent a viral illness and she was discharged with GP follow-up. Her GP referred her back to hospital due to worsening symptoms over the course of a week. She had no clinical signs of endocarditis or embolic findings. Blood cultures were positive for staphylococcus Aureus and CT showed discitis/osteomyelitis as well as pulmonary emboli. Trans-oesophageal echocardiogram showed a large vegetation arising from the anterior mitral valve leaflet with perforation and possible tricuspid valve vegetation.

She was taken to theatre for mitral valve repair and tricuspid vegetectomy. The A1 leaflet of the mitral valve had a large overlying vegetation with erosion onto the annulus and it was decided to replace the valve. The tricuspid valve had a region of abnormal tissue at the base of the septal leaflet and this was removed. She had an unremarkable post-operative course and was discharged to complete 12 weeks of IV antibiotics.