Case report
An otherwise well 59-year-old male was admitted to hospital with undifferentiated migratory polyarthralgia, fevers, raised inflammatory markers and a new pansystolic murmur. Transthoracic echocardiogram was performed to investigate for infective endocarditis and showed localised thickening of the anterior mitral valve leaflet with mild prolapse with moderate mitral regurgitation (see Figure 1). The findings were suspicious for endocarditis. Left ventricular cavity size and systolic function were normal. A transoesophageal echocardiogram revealed a left atrial mitral valve chordae. This was attached from the left atrial wall, near the ostium of the left atrial appendage, to the anterior leaflet near the junction of A1 and A2 (see Figures 2 and 3). Mild-moderate mitral regurgitation was present with multiple jets. The patient was discharged home with a plan for repeat echocardiography in 2 years to reassess the severity of his mitral regurgitation and left ventricular function.
Left atrial mitral valve chordae is a rare congenital abnormality of which is the prevalence is largely unknown. There have been few case reports worldwide and the clinical significance remains uncertain, ranging from incidental findings with mild-moderate mitral valve pathology managed conservatively(1-4) to severe mitral regurgitation requiring surgical intervention(5-13). There has been an isolated report of left atrial mitral valve chordae causing complex endocarditis(14). In our patient, recognition of this congenital abnormality was imperative to avoid over diagnosis and unnecessary surgical intervention, particularly given the differential diagnosis of infective endocarditis.
The origin of left atrial mitral valve chordae is proposed to be a result of a developmental defect during embryogenesis between the 14th and 17th weeks of gestation as the papillary muscles and chordae develop(4). Left atrial mitral valve chordae have been identified in children as young as 8-years-old(12), while one case was only diagnosed at the age of 85-years-old(6). At 59-years-old, our patient was asymptomatic from his valvular pathology and his finding was incidental. It has been hypothesised that symptoms may be delayed by progressive growth and dilatation of the left atrium, resulting in gradual traction of the aberrant chord eventually resulting in leaflet prolapse(6). Other suggested mechanisms include the chord holding the free edge of the leaflet in a scallop during diastole with the atrial kicking motion resulting in the development of mitral regurgitation(7) and traumatic injury to the free edge of the leaflet resulting in tethering and restricted mobility(10). Most cases in the literature describe involvement of the A2 leaflet of the mitral valve(3, 4, 8, 10-13), with one case involving the A3 leaflet(7) and one case involving P2 leaflet(6). We describe the first case which involves the junction of A1 and A2.